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Document:	PRO/RMS-11: An Introduction
Order Number:	AA-P099A-TK
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Pages:	44
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PRO/RMS-11:
An Introduction
Order No. AA-P098A-TK

November 1982
This document introduces the concepts and operations of Record Management Services (RMS-11) for the Professional Operating System (P/OS).

OPERATING SYSTEM AND VERSION:
SOFTWARE VERSION:

P/OS V1.0 or later
RMS-11 Version 2.0

digital equipment corporation · maynard, massachusetts

First Printing, November 1982
The information in this document is subject to change without notice
and should not be construed as a commitment by Digital Equipment
Corporation. Digital Equipment Corporation assumes no responsibility
for any errors that may appear in this document.
The software described in this document is furnished under a license
and may be used or copied only in accordance with the terms of such
license.
No responsibility is assumed for the use or reliability of software on
equipment that is not supplied by Digital Equipment Corporation or its
affiliated companies.
Copyright

by Digital Equipment Corporation
© 1982
All Rights Reserved.
Printed in U.S.A.

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CONTENTS

Page
PREFACE
DOCUMENT OBJECTIVES
INTENDED AUDIENCE
ASSOCIATED DOCUMENTS
CHAPTER 1

INTRODUCTION

CHAPTER 2

DATA STORAGE

• v
• • v
• v

DISK STRUCTURE • • • • • • • • • • • • • • • • • • 2-1
CHAPTER 3

FILE STRUCTURE
RECORD FORMATS • • • • • • • • • • • • • • • • • • 3-1
Fixed-Length Records • • •
• • • • • • • • 3-1
Variable-Length Records
• • 3-2
Variable-Length with Fixed Control (VFC) Records 3-2
Stream Records • • • • • • • • • • • • • • • • • 3-4
Undefined Records • • • •
• • • • • • • • 3-4
FILE ORGANIZATIONS • •
• • • • • 3-4
Sequential Organization
• • • • •
• 3-4
Special Case • • • • •
• • • •
3-5
Relative Organization • • • • • •
• • • 3-5
Indexed Organization
• • • • • • 3-6
ACCESS MODES • • • • • • • • • • • • • • • • • • 3-11
Record Access Modes
• • • • • 3-11
Block Access Modes • •
3-12
Access Mode Switching
• • • • • • • • • 3-13
FILE STRUCTURE INTERDEPENDENCIES
• • • • • • 3-13
File Organization and Access • • • • • • • • • 3-13
Summary
• • • • • • • • • • • •
3-15
FILE DESIGN • • • • • • • • • •
• • • • • 3-16

CHAPTER 4

OPERATIONS
• • • • • • 4-1
FILE PROCESSING
I/O Buffers and Data Transfer • • • • • • • • • 4-2
• • 4-3
Access Sharing • • • • • • • •
RECORD PROCESSING
• • • • •
• • • • • 4-3
• • • 4-4
Record Context • • •
• 4-5
Record Access Modes
• 4-6
Record Transfer Modes
• • • 4-6
BLOCK PROCESSING • • •
• 4-7
Block Access Modes •
4-7
MACROS AND SYMBOLS • •

INDEX

iii

FIGURES
FIGURE

1
2

3
4
5
6
7
8
9

Physical Disk Structure • • • • •
Logical Disk Structure • • • • • • • • • • • • •
Virtual-to-Logical Block Mapping
• • •
Fixed-Length and Variable-Length Record Formats
VFC Record Format • • • • •
• •
Sequential File Organization
Relative File Organization •
•
Indexed File Organization
Single Key
Indexed File Organization -- Multiple Keys
•

• 2-2
• 2-3
• 2-4
• 3-3
• 3-3
• 3-5
3-6
• 3-8
• 3-9

TABLES
TABLE

1
2

File Structure Interdependencies
File and Record Attributes

• • • 3-15
• • • • • 3-16

PREFACE

DOCUMENT OBJECTIVES
This document introduces the major concepts of RMS-11:
file organizations, and record access modes.

record formats,

It also
introduces the RMS-11 operations and defines key
required for understanding RMS-11 capabilities and functions.

terms

This document does not provide reference or usage information. You
should read
it,
however,
before you proceed to the other RMS-11
documents. See the Associated Documents section below.

INTENDED AUDIENCE
This document is intended for all users of RMS-11, including MACR0-11
and high-level language programmers. Nonprogramming users, programming
users who are new to
the Professional Operating
System,
and
programming users who are new to RMS-11 will find this document
useful.

ASSOCIATED DOCUMENTS
The PRO/RMS-11 Macro Programmer's Guide manual is a reference document
for
MACR0-11 programmers
that describes the macros and symbols that
make up the interface between a MACR0-11 program and the RMS-11
operation routines.
Chapter 4, Operations, of this manual provides a
background for the reference information.

CHAPTER 1
INTRODUCTION

The PDP-11 computer allows you to store large amounts of
information.
The combination of the software supplied by DIGITAL and the software
that you write allows you to access and manipulate that
information.
This means that you can store,
retrieve, and process (modify and
delete) data according to your requirements.
All businesses, for example, need to store detailed and up-to-date
personnel
information.
At
a minimum, this information would include
each employee's name, address, and social security number.
The employer will want to be able to retrieve this information in some
orderly fashion, perhaps in alphabetical order by employee name or by
social security number for tax purposes.
The employer also must be able to readily process the information: add
information on new employees, delete
information on employees who
leave, and modify
information that
is
incorrect or changes
(the
employee moves) .
The ability to store and retrieve
information and to
process that
information readily and
in some orderly fashion implies that the
information is stored in some orderly fashion, such as in
records.
A
record
is a
logical unit of data, that is, an item or collection of
items that are related in some manner.
The information on each employee -- name, address, and social security
number
would constitute one
record.
The
information on each
manufactured part in inventory -- part name,
number,
and price
would constitute another, different type of record.
To keep records of one type separate from
records of another type,
records are organized into files. A file contains groups of records of
the same type. One or more files, depending on the amount of data,
would contain all the records of a specific type.
In a small business, all the employee records would be stored
file; all the inventory records would be stored in another.

one

How the data is used helps determine how the records are stored in and
retrieved
from files so they can be processed, or used for a specific
purpose. Data storage and retrieval is also called access.
To obtain a complete report on all
employees,
the employer might
simply get each record, one after another. New records might be put at
the end of the file, one after another. To withhold state income tax,
the employer might use the address data to identify the records of
employees who reside in that state.

1-1

Introduction

The software that provides data access is RMS-11. RMS-11 is a set of
routines that allows your programs to gain access to and process
add, modify, and delete -- records and
files.
RMS-11 provides the
connection between your program and the stored data that your program
requires.
This document is an introduction to RMS-11. Data storage is described
briefly in Chapter 2.
File structure and access are described in
Chapter 3.
The RMS-11 operation routines that provide file and record
are introduced in Chapter 4.

1-2

processing

CHAPTER 2

DATA STORAGE

The data that your programs use typically is stored on mass-storage
devices,
called disks.
The operating system software controls thes~
hardware devices, and allows your programs to access the data stored
on them.
Each device
is controlled by a device driver, or software
that handles the input/output (I/O) -- the writing of data
into
and
reading of data out of storage.
The Files-11 Ancillary Control
Processor
(FCP)
is the P/OS file
control processor
that catalogues and maintains files on the disks,
and issues I/O requests to the device drivers.
The smallest unit of information stored on hardware devices
is the
bit.
A bit is an area of disk or tape surface for which the magnec1c
orientation can be changed
to one of two
values,
conventionally
designated Q and !·
Information typically is grouped into units of 8 bits, called
bytes.
Bytes are used, for example, to represent alphanumeric characters in
memory with the DEC multinational character set.
Other ways of
representing data,
particularly numeric data, may require 2 or more
bytes. A wor~, for example, consists of 2 bytes (or 16 bits).

DISK STRUCTURE
A disk is made up of one or more circular platters, arranged one above
the other
to form a cylinder. A disk is mounted on a drive, which is
the electromechanical
unit
for
reading
and writing---aata on the
platters. The disk platters spin and the read/write heads of the drive
move across the platters to access the data. Data is
usually written
on both sides of a platter.
Figure 1 shows how data is stored on a disk. On most disks supplied by
DIGITAL,
a
sector consists of 512 bvtes. A track consists of all the
radius on one ·disk platter,
and a
cylinder
sectors at a single
consists of all the tracks at the same radius on all the platters.
The disk drive can access all tracks on a
single cylinder without
changing
the position of the read/write heads. Any sector on a disk
thus has a unique physical address: its cylinder number,
its track
number, and its sector number on that track.

2-1

Data Storage
Disk Structure

Bit

p
I

Byte

I
I

III I
I~ I

...:::.

Sector

512

:; ..J

......

/
/
/
/

......

.......

,.,.

/
/

Track

Cylinder

Remainder of
Volume

ZK-1073-82

Figure 1: Physical Disk Structure
2-2

Data Storage
Disk Structure
The device drivers impose a simpler logical
addressing structure on
each disk.
They treat the disk as a single, logically contiguous,
series of data units, called blocks. A block contains 512 8-bit bytes.
Logical blocks are numbered sequentially, from 0 to n-1, where n is
-the numberofblocks on the disk. Figure 2 illustrates- this logTcal
structure. Blocks, which are logically adjacent, frequently correspond
to sectors, which are physically adjacent on the disk.

Logical
Block
Number ------.
0

Logical
Block
Number
n-1

Sector 1,
Track 1

ZK-1074-82

Figure 2:

Logical Disk Structure

On disk~ a file is simply a series of blocks, which contain your data
organized
into
records.
You can store multiple files on a disk. The
file control processor treats each file as a unit, ignoring any blocks
on the disk except those in the file being processed.
Figure 3 illustrates how blocks in a file -- called virtual blocks
may
be mapped
to
logical
blocks.
Virtual
blo~are
numbered
sequentially in a file from 1 to ~· where n is the number of blocks in
a file.
The blocks in a file, however, need not be logically contiguous. As
files are created or extended, the file control processor may allocate
blocks to the file that are not next to each other on the disk.
The
blocks in a file, then, are virtually contiguous.

2-3

Data Storage
Disk Structure

File

r::

' '

......

'
Logical blocks

A A A

......

B: B A A A

/
/

[

......

B B

File B

......

ZK-1075-82

Figure 3: Virtual-to-Logical Block Mapping
Note that a virtual block number (VBN)
and a logical block number
(LBN)
refer to the-5a"me physical unit of disk storage space. But
although a virtual block also has an LBN, a logical block has a VBN
only if it is allocated to a file.
To access files, the file control processor translates VBNs to LBNs
and issues an I/O request to the device driver. The device driver, in
turn, translates the LBNs to the physical location
(cylinder,
track,
and sector) that is to be read or written.
Disk storage offers two main advantages: 1) it allows both sequential
and random access and 2) it allows access sharing. Sequential access
means that virtual blocks containing data are stored and
retrieved
consecutively, one after another.
On the other hand, random access (also called direct access)
means
that a specific block containing data can be located and retrieved
without a search of all the blocks that precede it in the file.
The
time needed to access the data may thus be improved over sequential
access.
In addition, disk storage allows access sharina. This means that more
than one user can access the same disk at one time, and more than one
user can be allowed to open the same file at one time.

2-4

CHAPTER 3
FILE STRUCTURE

The operating system software
file control processor, device
drivers
handles files.
Your programs, however, must be able to
access the records within the files so they can process the data
within the records.
RMS-11 allows you to define the internal structure of files (the size
and arrangement of records within files) and provides operations that
allow your programs to read and write records in files.
RMS-11 thus
provides the interface between the operating system and your programs.
You define the internal structure of a file when
selecting record format and file organization.

Your selection of file organization may have to take into account
access modes that you will use to store and retrieve your data.

the

This chapter
organization,
operations.

you

create

introduces the concepts of
record
format,
file
and access modes. Chapter 4 introduces the RMS-11

RECORD FORMATS
RMS-11 does not handle, or process, data within records. Your program
does that.
However,
to retrieve or store a record for your program,
RMS-11 must know how large that record is. The record formats that
allow you to define for RMS-11 the size of your data records are:
•

Fixed length

•

Variable length

•

Variable length with fixed control (VFC)

•

Stream

These are the standard RMS-11 record formats.
In addition,
specify undefined as the record format for non-RMS-11 files.

you

can

Fixed-Length Records
In a file that contains fixed-length records, every record is the same
size.
The size
(number of bytes) is fixed at file-creation time and
cannot be changed for the life of the file.

3-1

File Structure
Record Formats
Typically, fixed-length records are used to contain data that is
always the same length. This is the most efficient use, although your
program need not supply data for every byte of a fixed-length record.
RMS-11 will simply store and return the fixed-size record regardless
of whether every byte in the record contains data that is meaningful
to you. Your program must be able to recognize that some bytes in the
record are "unneeded."
For example, you could use a fixed-length record
to
contain
information on manufactured parts including, say, part number, date of
manufacture, and price. Each of these fields would always be the same
length and would always be filled.
If you also used a field for a part name, that field would vary in
length with the names of the parts. However, as long as most of the
fields contain data whose length does not vary,
fixed-length record
format may still be the most efficient way to store your data.

Variable-Length Records
In a file that contains variable-length records,
records can be of
different lengths, up to a maximum size that you specify. This maximum
is fixed at file-creation time and cannot be changed for the life of
the file.
Because the number of bytes of data per record is not fixed,
each
variable-length record is only as long as it needs to be to contain
the record data. To keep track of the length of each record for
reading and writing, RMS-11 maintains a length field which is prefixed
to each record.
Thus, a variable-length record will require slightly more space than a
fixed-length record to hold exactly the same amount of data. However,
if the number of bytes of data in a
record must vary,
fixed-length
records would waste space in unneeded bytes, and variable-length
records may therefore be more efficient.
Figure 4 compares the fixed-length and variable-length record formats.
Typically, variable-length records contain text data that varies in
length:
for example, the names and addresses of employees. Using
fixed-length records for this information could result in many
unneeded bytes and inefficient use of storage space.

Variable-Length with Fixed Control (VFC) Records
A VFC record is much like a variable-length record except that in each
record
in
the file a fixed-length control area precedes the
variable-length data. This format allows you to construct records with
additional data that labels, or
identifies, the contents of the
variable-length portion of the record.
For example, in a text file,
each line of text constitutes the
variable-length portion of a record. The fixed-length control area of
each record contains a line number that indicates the sequence in
which the line occurs in the text file: line 3, say, in a text file of
10 lines (that is, 10 records). An editing program can use the line
numbers to locate a particular line of text easily in the file.

3-2

File Structure
Record Formats

Fixed-length
records

32 bytes

Variable-length
records

bytes

Length fields
ZK-1077-82

Figure 4: Fixed-Length and Variable-Length Record Formats
At file-creation time, you specify two sizes for the records in the
file:
the maximum size permitted for the variable-length portion and
the fixed size of the control area.
As for variable-length records, RMS-11 keeps track of the length of
each record by maintaining a length field for each record. Thus, in
a fixed-length
memory, a VFC record consists of a length field,
control area, and variable-length data.
Figure 5 illustrates the VFC record format.

Length
field

Fixed-length
control area

Variable-length
data

ZK-1078-82

Figure 5: VFC Record Format

3-3

File Structure
Record Formats
Stream Records

A stream record consists of a continuous series of ASCII characters
delimited by a special character or sequence of characters called
terminators: form feed,
line feed, or vertical
tab
are
all
terminators.
For example, a text file might consist of a series of stream
terminated by carriage-return/line-feed characters pairs.

records

RMS-11 considers each record a series of bytes; the length of a stream
record is determined by the position of the terminator.

Undefined Records
A file with undefined records either may have no record format or may
contain records that are not in one of the four standard RMS-11
formats described in the previous sections.
RMS-11 considers a file with undefined records as a series of blocks;
that is, it stores and retrieves data in units of 512-byte blocks.
Your program must be able to interpret the contents of the blocks.
RMS-ll's support of both undefined and stream records provides
compatibility with non-RMS-11 files. This means that, with some
limitations, RMS-11 can process files created under other file
systems.

FILE ORGANIZATIONS
The arrangement of records within files directly affects access
flexibility, or how quickly and easily RMS-11 can access those
records. Your selection of file organization, therefore, should take
access mode into consideration. For more information on access mode
selection, see the Access Modes section and the File Structure
Interdependencies section.
RMS-11 makes three file organizations available:
•

Sequential

•

Relative

•

Indexed

Sequential Organization
In a sequential file, records normally are arranged within the file in
the order in which they were written; that is, the first record
written is the first record in the file, and the record written most
recently is the last record in the file.

3-4

File Structure
File Organizations
You can add records to a sequential file only at the logical end of
the file. You can delete a record or series of records in a sequential
file only by truncating the file from a specific point to the logical
end of the file, which effectively deletes the record(s). You can,
however, update a record -- retrieve it, change its contents, and
rewrite it in the file -- as long as the length of the record has not
changed.
Sequential file organization is supported for all record formats.
addition, sequential files allow shared access for reading data.

Figure 6 illustrates sequential file organization.

End of file

1st
record
written

2nd
record
written

3rd
record
written

4th
record
written

5th
record
written

6th
record
written

•

n-1
record
written

nth
record
written

The 4th record written is
located between the 3rd
and 5th records written.
ZK-1079-82

Figure 6: Sequential File Organization

Special Case - In a sequential file with fixed-length records, the
records are numbered consecutively from 1 to ~· where ~ is the number
of records in the file. The record numbers are known as relative
record numbers. In this case, records may not be arranged in the file
in the order in which they were written. You can, for example, specify
that relative record number 5 be written before relative record number
4. When relative record number 4 is written later, it will be inserted
before relative record number 5. Fixed-length records in a sequential
file can be retrieved by random access.
In addition, RMS-11 supports the use of unit-record devices (such as
terminals and line printers) by treating them as sequential files.
That is, your program can write to and read from a unit-record device
in much the same manner as it would to a sequential file.

Relative Organization
A relative file consists of a series of cells, or fixed-length units
of storage. Each record within a relative file is stored in a cell;
however, not every cell need contain a record. The cells are numbered
consecutively from 1 to n, where n is the number of cells in the file.
As for sequential files with fixed-length records, the cell numbers
are known as relative record numbers.
To randomly access a record in a cell, your program must keep track of
the relative record number. One way to do so is to associate a value
within the record (for example, an order number) with the relative
record number.
3-5

File Structure
File Organizations
Because records are stored by relative record number, they need not be
arranged within the file in the same order in which they were written.
For example, order number 4 may be completed and its record written to
the file before order number 3. Thus, order number 4 will be stored in
cell 4, and cell 3 will remain empty until order number 3 has been
completed and its record written to the file.
Figure 7 illustrates relative file organization.
End of file

Cell
number

Record
1

Record
2

Empty

Record
4

Empty

Record
6

1st record 2nd record
written
written

3rd record
written

10th record
written

•••

n-1

Record
n-1

Empty

6th record
written
ZK-1080-82

Figure 7: Relative File Organization
The records in a relative file can be fixed length, variable length,
or VFC. Since there can be only one record per cell, RMS-11 determines
the cell size based on the maximum record size that you specify. This
means that with variable-length and VFC records there may be unneeded
bytes in a cell (much like fixed-length records in which there may be
unneeded bytes) •
Unlike sequential
capabilities:

files,

relative

files

permit

the

following

•

Random access by relative record number, regardless of
format

•

Record deletion

•

Access sharing for both reading and writing data

record

Indexed Organization
In an indexed file, records are arranged in ascending order by~- A
key is a data field within the record that RMS-11 uses to determine
the order in which to access the records in the file. This is the only
case in which RMS-11 interprets data within records~ thus, a record
can be identified by its contents, instead of by its position within
the file.

3-6

File Structure
File Organizations
When you create an indexed file, you must define one field of the
record as the primary~· A key is defined by its location within the
record, its data type, and its length. When a record is stored in that
file,
RMS-11 inserts the record in order based on the value that it
finds in the primary key field; that is, RMS-11 inserts the
record
after a
record with a lower or equal value in the primary key field,
and before a record with a higher value in the primary key field.
You can optionally define other fields of a record as alternate keys.
These keys specify alternate access orders for the retrieved records;
they do not affect the order in which the records are arranged within
the file.
The data type of values in key fields can be byte (character)
string,
signed integer, unsigned binary number, or packed decimal number.
For each data field defined as a primary or alternate key, RMS-11
constructs an
index. A primary index contains the values in the
primary key fields, and an alternate index contains the values in
alternate key fields.
An indexed file is a heirarchical, or tree,
structure consisting of
levels of records. The highest level(s) are the index records. The
data records comprise the lowest level. An indexed file consists of at
least two levels of records:
index and data.
Each index record
contains the highest key value in a group of records at the next lower
level plus a pointer to that group of records.
Thus, each key value provides a logical access path to locate a
specific record or set of records in a file. The indexes also allow
your program to retrieve your records in a specific order. RMS-11
stores the indexes in the file itself.
For example, to maintain employee files
in alphabetical order by
employee name, you could create an indexed file and specify the
employee-name field of the record as the primary key.
RMS-11 would
construct
a
primary
index
consisting of employee names,
in
alphabetical order, and insert the records in the file in that order.
Figure 8 illustrates an indexed file with only a primary key defined;
note that the data records contain other fields, including address and
badge number.
In many cases, employee records may need to be retrieved in different
orders; for
example,
the payroll may be processed by badge number
rather than by employee name. Thus, you might want to define the
badge-number field as an alternate key for the file.
Figure 9 illustrates an indexed file with an alternate key defined.

3-7

KEY DEFINITION

WYMAN

BAKER

....
'>!I

I-' "ll
(I)

PRIMARY INDEX
(Employee Name)

.....

lo-'

0(1)
>"!
<.Q

Ul
Ill rt

w
I
CX>

::l

..... c

ADAMS

BAKER

JONES

CLARK

TAYLOR

SMITH

WYMAN

°' rtc
('1"
t-'• l"'I
0 Cl)

::l
(fl

ADAMS

PINE ST

35112

CLARK

ELM AVE

24379

JONES

MAIN ST

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-DATA

19724

SMITH

HOLT RD

11733

WYMAN

MAIN ST

2254

RECORDS
ZK-1081-82

Figure 8:

Indexed File Organization -- Single Key

PRIMARY INDEX

AL TERNA TE INOEX
(B11:d9e Number)

(Emplo)'11e Name)

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.....

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CD..,.
I-'

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w
I

Ul t/l
OJ rt

SMITH

l.O

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'' I /
-_:::-'' !:-: J:. - - - - - ------ - - - - ;; (
---,,,,, _,,-/

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I
I

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/

CLARK

Figure 9:

ELM AVE

JONES

MA!N ST

I
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19724

SMITH

HOLT RD

Indexed File Organization -- Multiple Keys

1-'•C::
N 0

OJ rt
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0 CD
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tll

File Structure
File Organizations
You can optionally
individual keys:
1.

specify

three

key

value

characteristics

for

Duplicate values for primary and/or alternate keys.
This means that more than one record in the file can have the
same value for the key.
In the employee file example, duplicate key values could
allowed for employee name but not for badge number.

By default,
RMS-11 does not allow duplicate values for
primary keys but does allow duplicate values for alternate
keys.
2.

Changeable values for alternate keys.
This means that the data in the key field can be modified.
For example, if employee address was also an alternate key in
the employee file, key values would be allowed to change
in
case the employee moves.
If the field does change,
RMS-11 updates
index to reflect the new key value.

the

appropriate

By default, RMS-11 allows alternate key values to be changed.
Note, however,
that alternate key values can change only if
duplicate key values are also allowed.
Primary key values
cannot be changed.
3.

Null values for alternate keys.
This means that the data in the key field can be null,
that
is, have no value. It is possible, for example, that employee
information may be incomplete when the record is put into the
file, and that one of the incomplete fields is a key.
RMS-11 makes no alternate index entrv for such a
record;
if
the
record
is
subsequently
m~dified
to
include the
information, RMS-11 makes an entry in the appropriate
index.
Note that primary key values cannot be null, nor can a null
value later be changed unless the key was specified to be
changeable.
By default, RMS-11 treats any value in the
true key value.

key

field

When keys are character strings, you can also specify that keys are
segmented; that is, the keys consist of separate fields of the record.
For example, you can define a key in an employee file as consisting of
both
the
employee-name
and
badge-number fields.
RMS-11 will
concatenate the segments to form the key.
Indexed files permit fast sequential access (in key order)
access
by
key
value.
Indexed
files allow only
variable-length record formats.

3-10

and
random
fixed- and

File Structure
File Organizations
ACCESS MODES
The access modes are the methods that RMS-11 uses to store or retrieve
the contents of files. The contents of files can be either records or
blocks.
The record access modes are:
•

Sequential

·•

Random by record file address (RFA)

•

Random by key

The block access modes are:
•

Sequential

•

Random by virtual block number

(VBN)

In the sequential access modes, RMS-11 stores or retrieves records
blocks consecutively, one after another.

Sequential access is efficient when you need to read all the
records
or blocks
in a
file.
For example, you would use sequential record
access mode with an employee file to perform weekly payroll processing
because you would always want to access all of the employee records.
records
In the random access modes, RMS-11 stores or
retrieves
blocks directly, using an identifier unique to the required record
block. This means that your program, not the sequence of records
blocks within the file,
establishes the order in which records
blocks are processed.

or
or
or
or

Random access is efficient when you need to "jump around" in a
file,
rather than access all the records or blocks one after another. For
example, if your program needs to process only the
records for
employees who receive sick pay during a payroll period, you would use
a random record access mode to access only those records, by employee
name.

Record Access Modes
For sequential access, record storage or retrieval begins at a point
in the
file and continues with consecutive records through the file.
Your program issues a series of requests to RMS-11 to successively
retrieve the next record in the file.
Sequential access does not allow you to backspace through a file;
you
must
reopen the file, or rewind to the first record in the file, and
begin again at the first record.
For random by RFA access, RMS-11 uses the record file address (RFA) as
an
identifier to gain direct access to a specific record in a file,
without a successive search of all the records that precede
it.
The
RFA is a
unique record identifier that RMS-11 establishes for every
record that it writes to a file.
When RMS-11 stores a record in a file, it establishes the RFA for that
record and
returns the RFA information to your program. Your program
can then use the RFA to retrieve the record.

3-11

File Structure
Access Modes
Note that because only RMS-11 can establish the RFA, you cannot store
a record by RFA (that is, you cannot specify an RFA for the record).
RFA access can be used with files of any organization and
record
format;
it is the fastest way to read a record randomly in an indexed
file.
For random by key access, your program specifies an
identifier that
allows RMS-11 to gain direct access to a specific record without a
successive search of all the records that precede it.
For sequential
files with fixed-length records or for relative files, the identifier
is a relative record number (RRN). For indexed files,
the
identifier
is a key value.
To randomly read a record in an indexed file, your program specifies a
key value and the index (primary, first alternate, and so on). RMS-11
searches the index to locate the record with the specific key value.
For byte
(character)
string keys, your program can also specify the
number of characters on which the match is to be made; this is called
generic match.
In addition to specifying a key value or RRN,
match criteria:

you

can

also
is,

specify

•

An exact match on the key value or RRN,
that
record with the specified key value or RRN

only

the

•

A greater-than match on the key value or RRN,
that
is,
the
next record after the record with the specified key value or
RRN

•

A greater-than-or-equal-to match on the key value or RRN, that
is,
either 1) the record with the specified key value or, if
there is no such record, the record with the next higher key
value; or 2) the record in the cell with the specified RRN or,
if that cell is empty, the first record in a cell after the
specified RRN

For example, in an employee file the second alternate key might be the
social security number.
If you want to read the first record that
contains a social security number beginning with 175, you would
specify key number 2 (the index), key value 175, and that the match is
to be an exact match on the first three characters of the key.

Block Access Modes
For sequential access to blocks, RMS-11 stores or retrieves data as a
consecutive series of blocks. Your program issues a series of requests
to RMS-11 to successively access the next block(s) in the file.
For random by VBN access, your program specifies the virtual block
number
(VBN)
as the
identifier of the first block to be accessed.
RMS-11 uses the VBN to gain direct access to the specified block(s)
without a successive search of all the blocks that precede it.

3-12

File Structure
Access Modes
Access Mode Switching
RMS-11 allows your programs to change access modes -- either among the
three record access modes or between the two block access modes -- at
any time during file processing, as long as the
file organization
allows the access modes selected.
However, you must make the basic selection of either record access or
block access when you open the file. You can switch between record and
block access only by closing and reopening the file.
Access mode switching is most useful when a random access mode is used
to retrieve the first record or block of a series, and then sequential
access mode is used to retrieve subsequent records or blocks of that
series.
For example, if an indexed employee file uses the department code as
one of the alternate keys, your program could print a report on all
the employees in a specific department. It would do this by using key
record access mode to locate the first record whose department field
matches the specified key and then switch to sequential record access
mode to consecutively retrieve all the remaining
records of the
employees in that department.

FILE STRUCTURE INTERDEPENDENCIES
As the previous sections indicate, your selection of record format,
file organization, and access mode(s) cannot be made independently of
each other. For example, if you want to use VFC records, you cannot
choose indexed file organization; and if your records are undefined,
you must use a block access mode.

File Organization and Access
You can use sequential
record access mode with any RMS-11 file
organization.
The organization of the file determines the order in
which the records are stored and retrieved.
You can use random by RFA record access mode and VBN access mode with
any file organization.
For
random by RFA record access mode, your
program must save the RFAs established by RMS-11 when it stores the
records in the file.
Random by key record access mode also can be used with any file
organization. For sequential files, however, the record format must be
fixed length.
You can use sequential block access mode
organization, including non-RMS-11 files.

with

file

any

The block access modes may improve access time because RMS-11
ignores
file structure and record characteristics. Your program, however, must
be able to interpret the contents of the blocks.
Sequential Access to Sequential Files. If you use sequential record
access mode with a file of sequential organization, your program must
open the file and
read through the records one after the other
beginning with the
first record. Even though the record you require
may be near the end of the file, your program must read every record
that precedes it. In addition, records can be added sequentially only
at the end of a sequential file.

3-13

File Structure
File Structure Interdependencies
Sequential Access to Relative Files.
If you use sequential record
access mode with a relative file, RMS-11 will search for successive
record cells, ignoring cells that are empty. For example,
if a
relative file contains records in cells 1, 2, 4, and 8, and all other
cells are empty, RMS-11 will check each cell from 1 through 8 but will
read only RRNs 1, 2, 4, and 8, in that order.
To retrieve a specific record in a
relative file,
using sequential
access, your program first must retrieve all the records in all the
preceding cells.
To insert a record sequentially in a relative file,
RMS-11 puts the
record in the next cell after the cell just accessed {the cell with an
RRN one number higher than the current cell), if that cell is empty.
If the cell contains a record, RMS-11 will return an error code.
Sequential Access to Indexed Files.
If you use sequential record
access mode to retrieve records in an indexed file, you must specify a
key for RMS-11 to use to establish the order in which it will read the
records sequentially. The key you specify can be the primary key or
any alternate key. You can use sequential record access mode to
retrieve records in the order represented by any index for the file.
RMS-11 will retrieve the records in ascending order by key value; that
is, if you specify the employee-name key, all employee records will be
read beginning with the ~·s.
To store, or insert, a record sequentially in an indexed file,
RMS-11
uses the primary key value to insert the record in order in the file,
and updates the primary and alternate indexes according to the key
fields within the record.
In a series of sequential insertions, RMS-11 verifies that the primary
key of each new record has a value equal to or greater than the
primary key of the previously inserted record.
Random Access to Sequential Files. If you use random by key record
access mode with a sequential file, the record format must be fixed
length. Your program specifies the RRN of a record in the file and the
match criterion, and RMS-11 stores or retrieves that record.
When you are reading a record from a file, RMS-11 will retrieve that
record or return an error code if the specified record position lies
beyond the end of the file.
Note that RMS-11 does not initialize sequential files.
Thus,
if you
attempt to read a
record from a sequential file with fixed-length
records to which records have been randomly written, you may get
"garbage• data. That is, if you specify an RRN that is not beyond the
end of the file but at which no record has been stored, RMS-11 will
return whatever data happens to be at that location.
When you are writing records to a file and specify an RRN, RMS-11 will
store the record in that RRN's position in the file regardless of
whether a record with that RRN already exists. If the specified record
position lies beyond the end of the file, RMS-11 will extend the file
and store the record at the designated RRN.
If you know the RFA, you can use random by RFA record access mode to
read sequential files. This is the only random record access mode in
which your program can read sequential files of variable-length or VFC
record format.

3-14

File Structure
File Structure Interdependencies
Random Access to Relative Files. In random by key record access mode,
your program specifies the relative record number of a record's cell
in the file. RMS-11 then stores or retrieves the record in that cell.
When you are reading records from a file and specify an exact match on
an RRN,
RMS-11 will retrieve the record in that cell or return an
error code if the cell is empty.
When you are writing records to a file, RMS-11 will store the record
in the cell if the cell is empty or return an error code if the cell
contains a record. Only on an UPDATE record operation (see Chapter 4)
will RMS-11 write a record into a cell that already contains a record.
If you know the RFA, you can use random by RFA record access
read relative files.

mode

Random Access to Indexed Files. In random by key record access mode,
your program supplies the key value of a record in the file. RMS-11
then retrieves the record associated with that key value.
If you know the RF~, you can use random by RFA record access mode to
read indexed files.
RFA access is faster than key access because it
bypasses the searching of the index, but your program must keep track
of the RFAs.

Summary
Table 1 summarizes the RMS-11 file structure interdependencies.
Table 1: File Structure Interdependencies
Device
Disk

File Organization
Sequential

Record Access Mode

Record Format

Sequential,
Random by RFA

Fixed,
Variable,
VFC,
Stream

Random by key

Fixed

Relative

Sequential,
Random by key,
Random by RFA

Fixed,
Variable,
VFC

Indexed

Sequential,
Random by key,
Random by RFA

Fixed,
Variable

NOTE: The block access modes can be used to access files of any
organization and any record format. A block access mode must be
used to access a file with undefined record format.

3-15

File Structure
File Structure Interdependencies
FILE DESIGN
To create a file that will allow your program to store, retrieve, and
process your data records readily and efficiently, you must specify to
RMS-11 the file and record attributes. The attributes consist of the
device, file organization, and record format, plus additional values
that describe the characteristics of your files and records.
You can design files with the attributes you require and create them
by using the CREATE operation routine (see Chapter 4, Operations).
RMS-11 requires this information to access your data. The information
is stored in the file directory and, for relative and indexed files,
in the file prologue, and is passed to RMS-11 as required for the file
and record operations. The prologue consists of the first blocks of a
relative or indexed file and is used to store specific relative or
indexed file attributes that cannot be stored in the file directory.
Table 2 lists the RMS-11 file and record attributes.
Table 2: File and Record Attributes
Explanation

Attribute
File Attributes:
File specification

System node, device, account, file
name, extension, and version

File organization

Sequential, relative, or indexed

Allocation

Initial
blocks

Extension

The number of blocks to be added
to the file each time its size
must be increased

Bucket size 1

For relative and indexed files,
the number of blocks per bucket

Contiguity

Whether disk space is
to
be
file
in
allocated
to
the
logical
continuous,
adjacent
blocks

Location

Where the file is to be physically
placed on the disk

Protection

The type of
access
different
categories of user may have

Maximum record number

For relative files, the maximum
number of records the file can
contain

size

the

file,

(continued on next page)

1. See the File Processing section in Chapter 4 for more information.
3-16

File Structure
File Design
Table 2: File and Record Attributes (Cont.)
Attribute

Explanation

Record Attributes:
Record format

Fixed length, variable
VFC, stream, or undefined

length,

Record size

The size of the record in bytes:
for
variable-length and stream
records, record size is a maximum
length;
for fixed-length records,
record size is the exact length of
each
record;
for VFC records,
record
size
is
the
maximum
allowable length of the variable
portion

Control field size

For VFC records, the size in bytes
of the fixed-length portion of the
record

Block spanning l

For sequential files, the ability
for records to span physical block
boundaries

Record-output handling

Carriage control: how a record is
to be treated when ~ritten to a
terminal or line printer

Indexed File Key Attributes:
Key number

The number of the key

Key position

The location of the key within the
record

Key size

The length of the key, in bytes

Key data type

Byte
(character)
string, signed
integer, unsigned binary number,
or packed decimal number

Key name

The name for the key (optional)

Duplicate key values

The ability to have more than one
record in the file with the same
primary or alternate key value
(continued on next

page~

1. See the File Processing section in Chapter 4 for more information.
3-17

File Structure
File Design
Table 2: File and Record Attributes (Cont.)
Explanation

Attribute
Indexed File Key Attributes
(Cont.):

Changeable key values

The ability
key values

Null key values

The ability to have null alternate
key values

Segmented keys

The ability to use separate fields
of the record as the key value

Bucket fill sizel

The level to which buckets are
be loaded with records

See the File
information.

Processing

section

3-18

modify

Chapter

alternate

for

CHAPTER 4
OPERATIONS

The RMS-11 routines operate either on a file as a whole or on a record
or block within a file. The operation routines allow your programs to
add, retrieve, modify, and delete files, records, or blocks.
At the file processing level, RMS-11 makes requests of the file
processor to access files, by means of the directory and file
operations.
At the record processing level, RMS-11 stream
provide access to individual records.

and

record

operations

At the block processing level, RMS-11 block operations provide access
to the individual virtual blocks of a file, regardless of file
organization and record format.

FILE PROCESSING
The RMS-11 directory and file operations
your program and your data files.

are

the

interface

between

The directory operations affect only file specification entries in
directories. RMS-11 operations construct and use file specification
strings and file identifiers, including wildcard file specification
strings. The directory operations are:
•

ENTER -- places a file specification in a directory

• REMOVE
RENAME
• one

deletes a file spec i f ication from a directory

PARSE
• program

returns

•

replaces an existing file specification with
file

specification

information

new
your

SEARCH -- examines one or more directories for a specified
file and returns the file specification and location in a form
that can be used by other directory operations or by file
operations

4-1

Operations
File Processing
The file operations provide access to files as whole entities (that
is, they do not provide access to records within files). These
operations are:
•

CREATE -- creates a new file with the attributes
and opens it for processing

you

•

OPEN -- makes an existing file available for processing

•

ERASE
deletes a file and removes its
one is specified

•

EXTEND -- increases the allocated size of an open file

•

DISPLAY -- returns file information to your program

specify

terminates access to a file
directory

entry,

I/O Buffers and Data Transfer
For each file that is open for processing, RMS-11 requires that you
provide at least one I/O buffer for its internal use. RMS-11 either
transfers the data from disk to an I/O buffer, or from an I/O buffer
to disk.
Data in sequential files is transferred in blocks. The user can define
whether records in files can cross block boundaries. If you specify
block spanning when you create a file, records may continue across
15'IOCK boundaries. This means that they can be stored most efficiently
within a file.
When records are restricted by block boundaries, they must be less
than or equal to 512 bytes. Unneeded bytes may remain after each
record to the end of that block if the next record will not fit within
those bytes.
Data in relative and indexed files is transferred in buckets. A bucket
consists of one or more blocks that RMS-11 treats as a unit. The
bucket size, or number of blocks in a bucket, is user specified when a
file is created, and cannot be changed unless the file is redesigned.
Although records may span block boundaries, they cannot span bucket
boundaries.
For indexed files, you can also specify a bucket fill size. This file
attribute directs RMS-11 to load records into buckets only to the
particular level -- number of bytes -- specified, leaving free space
within each bucket. If a large number of random insertions are to be
made to the file, filling buckets only partially can
improve
processing time.
Buckets are an RMS-11 concept; thus, when RMS-11 requests an I/O
operation for a file, it directs the file control processor to move a
bucket by specifying the VBN for the first block in the bucket and the
size of the bucket in bytes.

4-2

Operations
File Processing
Access Sharing
The degree to which other users can access files is determined by
protection code and by access sharing.

the

The protection code is a file attribute (see Table 2)
that describes
the types of access granted to different users or potential users of
the file. This attribute is defined for the file at the time the file
is created, and is checked by the file control processor to determine
whether the user of an accessing program has the right to process or
delete the file. The protection code can also be changed when the file
is closed.
In many cases, more than one program must access the same file at the
same time.
RMS-11,
therefore, permits access sharing, which is
controlled by the accessing programs at the time a file is opened for
processing.
Each program to open a file supplies two items of information:
l.

The types of operations it will perform on records

The types of record operations it will allow other
programs to perform

accessing

The file control processor will check the file's protection code to
ensure that the
intended operations are allowed. If so, the file
control processor will then check that the operations requested and
the operations allowed are compatible with the operations being
performed and with the operations allowed by all current accessing
programs
(if any) of the file. To share access to the file, accessing
programs must not only meet the protection criteria but must also
specify compatible access sharing.
To protect data in a file in which access sharing is allowed, RMS-11
provides bucket locking. When a set of programs that are concurrently
accessing a relative or indexed file allows access sharing for write
operations, each bucket moved from disk is locked against access by
other programs until RMS-11 unlocks it, usually after completion of
the operation, or at the start of the next operation on the stream.
Access sharing also depends on file organization. All files can be
shared for
reading by any number of programs, but sequential files
cannot be shared for writing. Relative and indexed files can be shared
for writing by multiple programs.

RECORD PROCESSING
Once file access is established, the RMS-11 stream and record
operations are the interface between your program and the records your
program requires.
An access stream is a path between your program and the records
file (or blocks in a file; see the Block Processing section).
The stream operations are:
•

CONNECT -- initiates an access stream

•

DISCONNECT -- terminates a stream

4-3

Operations
Record Processing
•

FLUSH -- writes the contents of I/O buffers (modified records)
to the file

•

FREE -- releases control of the record or block most
accessed by the stream

•

REWIND -- resets stream context to the beginning of
(to the first record in the file)

•

WAIT -- suspends processing until an outstanding
operation is completed

recently
the

file

asynchronous

The record operations process records within files.
These operations
are of three types:
locate,
read,
and write.
Locate and
read
operations do not affect the data contents of the
records;
for
example, a FIND operation merely returns the position of a record in a
file. Write operations, on the other hand, may result in altered data;
for
example, an UPDATE operation replaces the contents of an existing
record with new data.
The record operations are:
e

FIND -- reads a record from a file to an I/O buffer
the current-record stream context to that record

GET -- reads a record from a file to an I/O buffer and then to
a
user buffer, and sets the current-record stream context to
that record

•

PUT -- writes a record from a user buffer to an I/O buffer and
then to a file

•

UPDATE -- transfers a modified record from a user buffer to an
I/O buffer
and then to
a a file, overwriting the previous
version of the record in the file

DELETE -- removes
indexed file

•

TRUNCATE -- effectively deletes all records
in a sequential
file
from
the current record through the logical end of the
file

existing

record

from

and

relative

sets

Record Context
Each record operation processes one record at a time along
the path
established by the access stream. RMS-11 keeps track of the stream's
position in the file so that it knows which record is the
target of
the operation.
The stream's position is called its context, which is
either the current record or the next record,
depending on the
operation.
The
stream's position changes at the completion of the
operation.
In general, the current record is the record that was the
target of
the
just-completed operation (the record operated upon), and the next
record is the record that follows the current record.
For example, when you use a CONNECT stream operation to establish an
access stream to
a
file opened by means of the OPEN or CREATE file
operation,
the current-record context is undefined
(no
record
operation has been performed) ,
and
the next-record context is the
first record in the file.

4-4

Operations
Record Processing
If the file is a sequential file and you use a sequential-access FIND
record operation,
the
target will
be the next record, which was
established by the CONNECT operation as the first record in the
file.
After
the FIND operation is completed, the current record will be the
found record (the first record in the file), and the next record will
be the record after the found record (the second record in the file).
If you then use a GET record operation, the target will be the current
record,
which was established by the FIND operation as the first
record in the file. After the GET operation is completed, the current
record will be the retrieved record (the first record in the file),
and the next record will be the record after the retrieved record (the
second record in the file).
To modify the record, you can use the UPDATE record operation.
Its
target will be the current record, which was established by the GET
operation as the first record in the file. After the UPDATE operation
is
completed,
the
current record will
be undefined
(it was
overwritten), and the next record will be the record that follows the
overwritten record.
After a DISCONNECT stream operation, there
next-record context.

current-record

Although only one record can be processed at a
time by means of a
stream, more than one stream can be connected to a relative or indexed
file. For example, you can open an indexed file and, with one stream,
use
the primary index to access records randomly and, with a second
stream, use an alternate index to access records sequentially.

Record Access Modes
For the FIND, GET, and PUT record operations, your program specifies
record access mode, which determines which record is the target of the
operation.
A sequential-access FIND operation can be used to position to
records
from
a
file of any organization. The target of a sequential-access
FIND operation is the next
record,
as established by a
previous
CONNECT or REWIND stream operation or a FIND or GET record operation
Repeated sequential-access FIND operations may be time-consuming
for
files with a large number of records. For relative and indexed files
and sequential
files with fixed-length
records,
you can use
a
key-access FIND operation, the target of which is the record whose RRN
or key value matches the one that you specify for the operation.
If you know the RFA for a disk file of any organization, you can also
use
an RFA-access
FIND operation, the target of which is the record
whose RFA matches the one that you specify for the operation.
Exactly the same dependencies exist for GET operations, which are
the
same as FIND operations except that
records are moved to the I/O
buffer and then on to the user buffer. In addition, the target of a
sequential-access GET operation depends on whether it was immediately
preceded by a FIND operation. If so, the target is the current record;
otherwise, the target is the next record.

4-5

Operations

Record Processing
A sequential-access PUT operation can be used to write records to a
file of any organization.
The
target of a sequential-access PUT
operation depends on the file organization: for sequential files,
the
target is the end of the file and for relative files, the target is
the next record. For indexed files,
RMS-11
inserts the
record
in
primary key order and updates the indexes.
The target of a key-access PUT operation for a relative file or for
a
sequential file with fixed-length records is the cell specified by the
RRN. For an indexed file, there
is no target;
RMS-11
inserts the
record and updates the indexes.
Note that you cannot specify RFA access for PUT operations.
information, see the Access Modes section in Chapter 3.

For

Record Transfer Modes
Your program can use either of two record transfer
record operations: move mode or locate mode.

modes

perform

In both modes, a user buffer, established by your program, is required
in addition to
the
I/O buffer.
For read operations in move mode,
RMS-11 first transfers the data into the I/O buffer, then copies the
record into the user buffer for processing by the program.
For write operations in move mode, your program builds or modifies the
record
in the user buffer. Then, upon a write request, RMS-11 copies
the record into the I/O buffer before writing it to the file.
In locate mode, on the other hand,
your program can,
under some
circumstances,
access the record in the I/O buffer directly. This may
reduce the amount of data movement, thereby reducing processing time.

BLOCK PROCESSING
Your program can bypass RMS-11 file and
record structures and use
block access to process 512-byte blocks one after the other. Your
and the number of
program identifies the starting VBN of the file
bytes to be accessed.
When you
blocks,
stream's
writable

use block access, RMS-11 regards the file
as a series of
rather than as a series of records. RMS-11 keeps track of the
position, or block context, which is either readable block or
block, dependTi1(JOn the operation.

Block access requires minimum time and space for processing;
however,
your program must be able to interpret the contents of the blocks.
The block access operations are:
•

READ -- gets blocks from a file

•

WRITE -- puts blocks in a file

4-6

Operations
Block Processing
Block Access Modes
For the READ and WRITE operations, your program specifies block access
mode -- sequential or random by VBN -- which determines which block is
the target of the operation. Upon completion of an operation, RMS-11
resets the readable-block and writable-block contexts.

MACROS AND SYMBOLS
The RMS-11 operation routines are fully accessible only from a
MACR0-11 program. High-level languages restrict your options for some
operations; see your particular language documentation for information
on its support of RMS-11.
The interface between a MACR0-11 program and the RMS-11 operation
routines is defined by the RMS-11 macros and symbols. Your program
uses the RMS-11 macros to call the RMS-11 operation routines.
Information is passed between the calling program and an RMS-11
operation routine by means of control blocks, which consist of
structured series of data fields that contain the
information.
The
information passed includes the attributes that your program supplies
to RMS-11 for file and record access and the returned values that
RMS-11 supplies to your program as a result of an operation. RMS-11
macros also allow your program to declare and manipulate the control
blocks.
The fields of a control block are referenced by symbols that name the
locations of fields within control blocks (field-offset symbols) and
the codes and bit masks used within the fields
(code and mask
symbols).
The RMS-11 control blocks are:
•

Area allocation (ALL) block -- contains
file area

•

File date (DAT) block -- contains file creation
dates

•

File access block (FAB)
contains information about the
file,
including device,
file attributes, access sharing,
record format, record blocking, record-output handling

•

File key (KEY) block -- contains index and key information for
an indexed file

•

File name
(NAM)
information

•

File protection
(PRO)
protection information

•

Record access block (RAB)
contains
stream or record and record access mode

•

File summary (SUM) block
for an indexed file

block

contains
block

information

file

contains

and

about

revision

specification
file

information

owner
about

and
a

contains file and area information

Operations
Macros and Symbols
In addition to calling RMS-11
operations
and
declaring
manipulating control blocks, RMS-11 macros allow your program to:

and

•

Declare and manipulate memory space (pools)

•

Declare RMS-11 facilities that are
operations based on file organization

•

Extract from a macro library definitions for RMS-11 macros and
symbols

4-8

required

for

certain

INDEX

Access, 1-1
block, 4-6
direct, 2-4
modes, 3-11
random, 2--4
sequential, 2-4
sharing, 2-4, 4-3
read, 3-5 to 3-6
write, 3-6
stream, 4-3
Access modes, 3-1, 3-11
and file organization, 3-13
block, 3-11 to 3-13, 4-7
sequential, 3-12
VBN, 3-12
random access to
indexed files, 3-15
relative files, 3-15
sequential files, 3-14
record, 3-11, 4-5
FIND operations, 4-5
GET operations, 4-5
key, 3-12
PUT operations, 4-6
RFA, 3-11
sequential, 3-11
sequential access to
indexed files, 3-14
relative files, 3-14
sequential files, 3-13
switching, 3-13
Access sharing, 2-4, 4-3
read, 3-5 to 3-6
write, 3-6
ALL control block, 4-7
Alternate keys, 3-7
Attributes, 3-16, 4-3

Byte, 2-1
Cell, 3-5
Changeable keys, 3-10
CLOSE operation, 4-2
CONNECT operation, 4-3
Context, 4-4
block, 4-6
readable block, 4-6
writable block, 4-6
current record, 4-4
next record, 4-4
Contiguity
virtual, 2-3
Control blocks, 4-7
ALL, 4-7
DAT, 4-7
FAB, 4-7
KEY, 4-7
NAM, 4-7
PRO, 4-7
RAB, 4-7
SUM, 4-7
CREATE operation, 4-2
Current record
see Context
Cylinder, 2-1

Bit, 2-1
Block, 2-3
access, 4-6
context, 4-6
readable block, 4-6
writable block, 4-6
logical, 2-3
operations, 4-6
processing, 4-1, 4-6
spanning, 4-2
virtual, 2-3
Block access, 3-11
Block access modes, 3-12 to 3-13
sequential, 3-12
VBN, 3-12
Bucket, 4-2
locking, 4-3
Bucket fill size, 4-2

DAT control block, 4-7
Data storage, 2-1
Data type
key values, 3-7
DELETE operation, 4-4
Designing files, 3-16
Dev ice, 2-1
disk, 2-1
driver, 2-1
unit-record, 3-5
Direct access
see Random access
Directory
operations, 4-1
DISCONNECT operation, 4-3
Disk
drive, 2-1
structure, 2-1
cylinder, 2-1
platter, 2-1
sector, 2-1
track, 2-1
DISPLAY operation, 4-2
Drive, 2-1
Duplicate keys, 3-10
ENTER operation, 4-1
ERASE operation, 4-2

Index-1

INDEX

EXTEND operation, 4-2
FAB control block, 4-7
File, 1-1
design, 3-16
non-RMS-11, 3-4
operations, 4-2
processing, 4-1
specification, 4-1
structure , 3-1
File control processor, 2-1, 4-3
File organization, 3-1, 3-4
indexed, 3-6
alternate keys, 3-7
changeable keys, 3-10
duplicate keys, 3-10
index, 3-7
keys, 3-6
null keys, 3-10
primary key, 3-7
segmented keys, 3-10
random access to
indexed files, 3-15
relative files, 3-15
sequential files, 3-14
relative, 3-5
cell, 3-5
RRN, 3-5
sequential, 3-4
sequential access to
indexed files, 3-14
relative files, 3-14
sequential files, 3-13
File specification, 4-1
wildcard characters, 4-1
Fill size
see Bucket fill size
FIND operation, 4-4
access modes, 4-5
Fixed-length record format, 3-1
FLUSH operation, 4-4
Format
see Record format
FREE operation, 4-4
Generic match, 3-12
GET operation, 4-4
access modes, 4-5
I/O, 2-1
buffers, 4-2
Index, 3-7
Indexed file organization, 3-6
alternate keys, 3-7
changeable keys, 3-10
data records, 3-7
duplicate keys, 3-10
index, 3-7
index records, 3-7
keys, 3-6

data type, 3-7
null keys, 3-10
primary key, 3-7
segmented keys, 3-10
tree structure, 3-7
Input/output
see I/O
KEY control block, 4-7
Key record access mode, 3-12
Keys, 3-6
alternate, 3-7
changeable, 3-10
data type, 3-7
duplicate, 3-10
match criteria, 3-12
null, 3-10
segmented, 3-10
LBN, 2-4
Locate mode, 4-6
Locking buckets, 4-3
Logical block, 2-3
Logical block number
see LBN
Macros, 4-7
Mass-storage device, 2-1
Match criteria, 3-12
Mode
see Access modes
see Record transfer modes
Move mode, 4-6
NAM control block, 4-7
Next record
see Context
Non-RMS-11 files, 3-4
Null keys, 3-10
OPEN operation, 4-2
Operations, 4-1
block, 4-6
CLOSE, 4-2
CONNECT, 4-3
CREATE, 4-2
DELETE, 4-4
directory, 4-1
DISCONNECT, 4-3
DISPLAY, 4-2
ENTEND, 4-2
ENTER, 4-1
ERASE, 4-2
file, 4-2
FIND, 4-4
access modes, 4-5
FLUSH, 4-4
FREE, 4-4
from high-level languages, 4-7
GET, 4-4

Index-2

INDEX

access modes, 4-5
OPEN, 4-2
PARSE, 4-1
PUT, 4-4
access modes, 4-6
READ, 4-6
access modes, 4-7
record, 4-4
REMOVE, 4-1
RENAME, 4-1
REWIND, 4-4
SEARCH, 4-1
SPACE, 4-6
access modes, 4-7
stream, 4-3
TRUNCATE, 4-4
UPDATE, 4-4
WAIT, 4-4
WRITE, 4-6
access modes, 4-7
Organization
see File organization
PARSE operation, 4-1
Platter, 2-1
Primary key, 3-7
PRO control block, 4-7
Processing blocks, 4-1, 4-6
Processing files, 4-1
Processing records, 4-1, 4-3
Prologue, 3-16
PUT operation, 4-4
access modes, 4-6
RAB control block, 4-7
Random access, 2-4
key, 3-12
match criteria, 3-12
RFA, 3-11
VBN, 3-12
READ operation, 4-6
access modes, 4-7
Record, 1-1
data, 3-7
index, 3-7
operations, 4-4
processing, 4-1, 4-3
see also Record format
Record access modes, 3-11
key, 3-12
RFA, 3-11
sequential, 3-11
Record file address
see RFA
Record format, 3-1
fixed-length, 3-1
stream, 3-4
undefined, 3-4
variable-length, 3-2
VFC, 3-2

Record transfer modes, 4-6
locate mode, 4-6
move mode, 4-6
Relative file organization, 3-5
cell, 3-5
RRN, 3-5
Relative record number
see RRN
REMOVE operation, 4-1
RENAME operation, 4-1
REWIND operation, 4-4
RFA, 3-11, 3-14 to 3-15
RRN, 3-5, 3-12, 3-14 to 3-15
SEARCH operation, 4-1
Sector, 2-1
Segmented keys, 3-10
Sequential access, 2-4
block, 3-12
record, 3-11
Sequential file organization,
3-4
RRN, 3-5
SPACE operation, 4-6
access modes, 4-7
Spanning blocks, 4-2
Storage
data, 2-1
Stream
access, 4-3
operations, 4-3
Stream record format, 3-4
terminators, 3-4
SUM control block, 4-7
Switching access modes, 3-13
Symbols, 4-7
code and mask, 4-7
field-offset, 4-7
Terminators
stream records, 3-4
Track, 2-1
Tree structure
indexed file organization, 3-7
TRUNCATE operation, 4-4
Undefined record format, 3-4
Unit-record devices, 3-5
UPDATE operation, 4-4
Variable with fixed control
see VFC
Variable-length record format,
3-2
VBN, 2-4
access, 3-12, 4-6
VFC record format, 3-2
Virtual block, 2-3
Virtual block number
see VBN

Index-3

INDEX

WAIT operation, 4-4
Wildcard characters, 4-1
Word, 2-1
WRITE operation, 4-6
access modes, 4-7

Index-4

PRO/RMS-11: An Introduction
AA-P098A-TK

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