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AC-S866B-MC

October 1984

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Document:	CHQFSB0 XXDP+ File Struct Doc Oct84
Order Number:	AC-S866B-MC
Revision:	0
Pages:	15
Original Filename:	http://bitsavers.org/pdf/dec/pdp11/xxdp/diag_listings/AC-S866B-MC_CHQFSB0_XXDP+_File_Struct_Doc_Oct84.pdf

OCR Text

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SEQ odO

IDENTIFICATION

PRODUCT MAttE:
P~OOUCT

MAttE:

PRODuct DATE:
"AINtAlNER:

AC .. S866B-f1C
CHQFSBO XXDP. FlLE STRVCT DOC
8 Oct 1984
Low End Diagnostic Engineering

The in'Of'. .tiOft in this docUMent i. subject to chenge without
notice en4 should not be cOftstrued .s • cOMitMnt bV Digital
ECIU l_nt Co~".t iOf". 0 iii t.l EQU i PMnt Corpor.t ion ........
no re~.ibilitv for any .rro"s that .av appe.r in this docUMent.

No ~.ibil;tv i •••sUMed 'or the use 0" reliabilitV 0'
software Oft .QUi ....nt that i. not suppl ied by Digital or its
Iff illa'e. cCMlPaft i ••.
COPy"itht (C): 1981;1984 bv Dititll EquiPMnt Corporation
The 'ollowi"V .". tr ....."les

0' Digitll EquiPMent Corporat ion:

Digital. POP. UNIBUS. HASSBUS. DEC. DECVS. DECtape. DEC/Xl1

-........ ..
-.......

-~----------.- -. ..,-.

--~~

---..... ------

-~"'-

C1
DATE:
8 Oct 1984
CHARGE NUMBER: E98-08823

XXDP. FILE STRUC1URE
SPECIFICATION
REVISION 1.0
XXoP Version: 1.3

M.i~t.ined

R.vilio~

Revision
._ili __ .".

0.0

1.0

by:

MSD DIAGNOSTIC eNGINEERING

History:

Date
17 FEB 1981
8 Oct 1984

By
Michael Cinnamon
L.,.ry p,.uche

SEQ 0002

,.",-

01
Teble of Contents

---.-------------

Page

INTRODUCTION
Z.o
DATA STRUCTURES
DATA BLOCI(S
2.1
2.1.1 RANDOH ACCESS DEVICES
2.1.2 SEQUENTIAL ACCESS DEVICES
FILE STRUCTURES
3.0
TYPES OF FILES
3. 1
3.1.1 CONTIGUOUS FILES
3.1.2 TEXT FILES
3.2.3 BINARY FILES
HEDIA STRUCTttr"t"'
4.0
4.1
RANtOM ACCES~ STRUCTURE
4.1.1 MASTER FILE DIRECTORY
4.1.2 USER FILE DIRECTORY
4.1.3 BIT MAF4.1.4 RANDOM ACCESS DEVICE INFORMATION
SEQUENTIAL ACCESS DEVICE
4.2
4.2.1 MAGTAPE
4.2.2 CASSETTE
GLOSSARY
5.0
1.0

...... -...

---~--.---.-----.-

2
2
2
2
3

3
3

3
3
4
4

4
5
7

e
9

11
11

12
13

....

--,,--_._--_._.._._--_ ..

SEQ 0003

El
.. INTRODUCTION
-._._ .. _-_ ..

1.0
_._

The .t"uctu". that XXOP. u... fo" Ito"ino files on Mdia is unique
to XXDP.. The .t"uctu"e .... o";oinaily ~a.ed on DOS-II but it has
.ince been MOdified to accOMModate the needs of XXDP., although
llefty .i.ila"iti •••till exist.
XXop. • ...."t. both ..
accesa end .eQUent i al eccess type
devic••• " d'".cto ..., index .t... uctu ...e i. used fo" .ccesstng files
on "andOIi Ke... type dev i eea such as disks. F0'" sequent i al
devic•• litee II!tt. . . . h...... ...ecord containing file info...",ation
pr.c••• each f.l ••

en'"

DATA STRUCTURES
.......
_-_ .•..•.••. ........ -............ ..

2.0

The b.. ic ~it ,of data trans'er"ed in XXDP. file I/O is a data
block. A data Dlock i. de'ined as a g~oup of 512(10) 8 bit bytes.

2.1.1

a...... Acce•• o.vice•.

Ott ..en_. ace••• dev ice.. data blocks are addr.ssed by the i r
= a l block fluMe.... Logical block...... data block. thet a".
··"1iD1. i., • 1 in,••" o".".d , ••hiOf\. The 0"'.'" . . anges f ...o", 0
to " .. 1 ........... " i. the .a. . . . .,UIIbe" of blocks .uppo"t.d on the
The v.riable " v.rie. depend'"g Of\ the device but is not
device.
thll'\ 65535 (10). Th j . . ...,. th.t "0 ..ette" how ..any data
.lock. Dhy.ically ".,ide on • device onl" the fi ... st n blocks a"e
ecce•• ible.
Logical block••re "ot .,.o••••rily the sa.. as physical blocks.
A jhys;cII block is usuilly liMit.d to the IIIIOUftt of date a
Dhy •• oIl Metor contain. which .ay be 1••• than 512 (10) bytes.
Al M a phy. i ell block hOUMS at _.t one log i cal block.
A linked list of lotical blocks is set up using linked blocks.
A li.,k.d block is a l,ical block that devotes the fi ....t word
of the block to conte." a ink word. The link ...d contains the
logical block nUMbe" of anoth... block. A Z."O link word indicates
that the block contai"ino it is the list block of the list.

.....t....

SEQ 0004

Fl
P.ge 3
2.1 .. 2 Sequential Acce•• Device.

-_.-----.-------------------- --

On sequential acc... device••uch •• Mgtepe .nd c ....tt.

data
block. al"e stored •• 512 byte ,.eco....
a.causc xx6p. us.s
the . _ ...
i te "out i ne.
both random and s.quent i al
ecce.. .viee•• logic.l linked blocks a,.. stor.d on sequenti.l
t".e device••

ed'",.

'0"

.....ve,., the 1 ink NO..d i. only SOlIe non - z.,.o value to i nd i cate
that the... • . . . .,.. Illock. in the list. A ze,.o link wo,.d
indicat.. the l.st block
the list.

3.0 FILE STRUCTURES

.. _---- .. --._.-._-_.

1.1 T.,.. Of File.
TM,.. .... three type.
files suppo,.t.d by )CXOP... Th.y a,.e
COfttiguous 'ile•• text files and bina,.y files. This does not mean
that othe.. tyte. of fil •• cannot be stored on an XXDP. medium. but
XXDP. Oft.ly
the clIP. il i ty to produce these types .

h..

3.1.1 COfttiguous File•
.... -.
A conti~ file i • • s.t of l,ieal blocks Nhich physically
.... i de ._di at.ly
adjacent
0 one anothe,. on the Md i a.
The t.N' i _ct i at• .! y adJacent' is obv i ous for sequent i.1 dev ices
~t not QUite as eppa,.ent '0" ,.andoll access devices.
For these
it Means fo.. any lOOte81 block n, the next conttguous block is
located et ft-l ..
Conti~sfiles a,.e no,..ally used to store eo,.e image data sueh
as thi XXDP - lIOn ito,. •

... --- ..

-.~-.--.-

1.1.2 Text Fil••
T.xt fil •••"e ••• up of a s.ries of link.d blocks.
Each
block contains 510(10) 8 bit ASCII cha,.aete,.s. An ASCII null
ch.,.ect.,. (a byte with a val,.J. of ze,.o) is used to i nd i eate the
end
the , H••

<~o

........ _

........... _

_ . . ..

"'110

.~,~~_~ _ _ _ _ _ . _ ,

__ ~.

- ,.......- . - . - . . . . - - - - - . - . " '... --~--

SEQ 0005

Gl
Page 4
3.1.3

Bin.~y

files

Bina~y

files a~e used to sto~e executable p~og~aMs. They a~e Made
a ..~i.s of linked blocks each of Nhich contain sections
of the p~~~... These sections a~e in absolute fO~Matted bina~y
end the~e is at least one pe~ l~ical block. The absolute
fo~atted bina~y specification is as follows:
U@ of

BYTE
1

--... _------_._----------------------_._---------------- Contains. value of 1 to indicate
point.

- Contains a value of O.

sta~ting

This Must follow byte 1.

- BYTE COUNl • nUlftbe~ of bytes (N) in this bina~y block.
Includes byt~s 1. 2. 3 end 4 t exclUdeS the checksuM byte.
If BYTE COUNT • 6. then this is a TRANSFER BLOCK
If BYTE COUNT • 5. then this is a BIAS BLOCK
5.6

Contains the sta~ting ....mory add~ess whe~e the follow;ng
data bytes are to be stored.

1 to N - Data bytes.

N .. 1

N (& 509. MaxiMUM numbe~ of data bytes is 503.

- CHECKSUt1 byte. The checksUM is the 2's cOlIIPleMnt of tne
SUM of the data in all n bytes.
It is
iono~ing overflow end ca~ry conditions.

generated

TRANSFER BLOCK is at the end of a binft~y file and is indicated by
a bi"ary block that has a byte count of 6. Bytes 5 and 6 contain
the prog~.. 's tr8ftsfer address.
BIAS BLOCK is indiacted by a binary block with a byte count of 5.
Bits 0 end 1 of byte 5 ~ep~esent bits 16 and 17, respectively, of
the load address for the next bina~y blOCk.

4.0 MEDIA STRUCTURE
4.1 RandoM Access St~ucture
-.---.-~--------------.----All
XXop. ~andoM access devices a~e set up to contain the
followino pieces of inforMation:
bootstrap. MOnitor cor..
iMage! .aster file directories (HFO). user file directories (UFO),
artd bit .eps.
The bootstr, is a program that always occupies logical block 0 on
the device. t is a core iMage that IS placed there by the utility
c~8ftd 'SAY"t.
The bootstrap knows where on the disk the monitor
core i.age resides.
The MOnito~ core iMage is a 90ntiguous fi!e.that is 16 blocks
Ion,. It IS placed on the disk bV the ut,l,tv command tSAYMt. It
poSItion depends on the type of disk. The MFD is a table of
information which contains pointers to the UFOs a~d the bit maps.

SEQ 0006

Page 5

SEQ 0007

4.1.1 "aster File Directory

.. ---.-----.----------------

The ~D is placed on the disk by the utilitv 'ZERO' command. The
~ of disk dete".ines which of' two Ya"iettes of i1FD is used and
,.. it i. on the dey ice.

fiFD VARIETY '1

WORD OFFSET
INTO BLOCK

f1FD1:
!

LIN< TO fiFD2

· INTERLEAVE FACTOR
.
!,-------------------------------,

·!,._-----------------------------,
.
BIT "AP START BLOCK •
!

·..

.
POINTER TO BIT "AP .1
!-----------_._-----------______ I
!
POINTER TO BIT "AP '2
!

~-~-----.----------.----.-----.

!._----------------------------•

·••
!•

!--------------_
.. _------------0
j,._----------------------------UNUSED

2
3
4

N.2
N.3

POINTER TO BIT "AP .N

N.4 to 255

The inte"leaYe f'actor is used as part of' the 'block allocation
alaorith•• No".ally blocks a"e allocated contiguously if possible
but on certain deYIC•• , the atnOUf'\t of time it takes to access a
linked list of blocks is "educed by placing each block of the list
a constant nUliber of block$ apa"t. Th i s constant nUillber is the
int."leave facto". The pointe". in the table are the logical block
n~rs of the ..espectiYe bit Maps.
f1FD2:

.-------------------------------.
o
••

·•__ .. _---_._._._-------_ ..... _-•

•...•.... ---_._-- ... _--- .. _-----i POINTER TO rIRST UfD BLOCK

••.. __

.--_ ................ _-- ... __ ..... ,

- 005-11 UIC [1.1].

- logical block number
of' first UFD block.

numbe .. of wo..ds in
each UFD entry;

•

!
~. (10)
AL WAY S !
••
!---_._-------_ ... _-_._--_._----!•I
!

•

UNUSED

•

5-255

• • • • _ . _ . - - - - - - _ . - - _ • • _._-- __ • ___ 1

..... -.- ..

Link of zero
indicates no more

MFDs •

401

WORD OFFSE"T
INTO BLOCK

-.-~---------.---.----.

...

~. -""' .,.-

. ,-

---""--- - .

~.----.------.- " ....

_----.

--, . .-_.....- ... --,--~

Page 6

t1FD VARIETY '2
t1FD 1/2:

WORD OFFSET
INTO BLOCK

o
•
·!-_
•• ---------------------------

! POINTER TO FIRST UfO BLOCK

1
2
3
4
5

!------------------------------! • OF UFO BLOCKS
!------------------------------! POINTER TO FIRST BIT HAP BLOCK
!------------------------------! • OF BIT HAP BLOCKS
!------------------------------! POINTER TO ~D 1/2
o
••

!-.---~--.----.--------.--------.
! NUMBER OF SuPPORTED BLOCKS

!------------------------------! • OF BLOCKS PREALLOCATED
••

6
7

•
•
!------_
.. _--------------------! INTERLEAVE FACTOR
•
•

!,------------------------------0
!,---------------_._------------TRACK • SECTOR ADDRESS FOR BAD

12
13

! t1ONITOR CORE I"AGE

!-----------_._._
.... _----------!!
CYLINDER ADDRESS FOR BAD

SECTOR ~ILE (SINGLE DENSITY) !
------.-------------------.-.-~!
TRACK • SECTOR ADDRESS FOR BAD!
SECTOR FILE (DOUBLE DENSITY) !
----_._------_._---_ .. _--------!
CYLINDER ADDRESS FOR BAD
!
• SECTOR FILE (DOUBLE DENSITY) !

--.~-

~.~ -~-.-----

- .-.---

number of blocks on
device ~eserved for
device st~ucture
in'o~"ation.

!._-------.---_._---------------0
1 ______ --_._-----_._---_._-----! POINTER TO FIRST BLOCK OF

! SECTOR FILE (SINGLE DENSITY)

14
15

)

.) ---------

)
)
)
)

)
}
}
}

}
}
}

}
)

> <

}
}
)
)
)

refers to the
location on
the disk of the

DEC STD 144
bad sector file.

......... ~.. --

.. -----.-----.--- -_ .. _--------_. ----.

SEQ 0008

Jl
Page 7
4.1.2 User File Directory
The User File Directory (UFO) is a list of the files on the media.
It is cr.ated by the utility 'ZERO' co.and. The UFO is arranged as
a linked list of 1~ic.1 blocks and the number of blocks that the
UFO occup i es depends on the dev ice. Each block of the UFO conta i liS
spece for 28(10) file entries •

.! -------------------------+
LIN< TO NEXT UFO BLOCK
!,------------------------FILE ENTRY '1
1 ______ - - - - - - - - - - - - - - - - - - -

! FILE ENTRY .2

!------------------------•

·!

1 ______ - - - - - - - - - - - - - - - - - - -

! FILE ENTRY '28(10)

+------------------------Each file entry is a table of 9(10) words that contains the
following information about the file.

.-------------------------+
!
FILE NAt1E
•

··•
!
FILE EXTENSION
•·
!------------------------1 ______ - - - - - - - - - - - - - - - - - - -

·
I

·••

WORL

1
2

FILE DATE

ACT-I! LOGICAL END

FIRST BLOCK •

FILE LENGTH

LAST BLOCK

ACT-II LOGICAL 52

........

... ~.~.---"~-.- ....'"

Six character encoded RAO-SO.
Zeros if deleted file.
Three character encoded RAO-SO.
Zeros if deleted file
- 005-11 format OATE given the
file when put on media
ACT-ll use only.
Not used in XXOP+.
- 1st logical block that file
occupies.
- Number of logical blocks that
file occup i es .
- Block number of last logical
block that the file occupies.
- ACT-II use only.
Not used in XXOP+ .

---- ....-........._-------_._---. -----_ _--_. ---.
...

SEQ 0009

1(1
Page 8
4.1.3

Bit Hap

--- .. _--------

The bit - , is • file that contains the current status of every
supported ogical block on the Mdia.

lIte bit Map is arranged as ali nked 1 i st of log i cal blocks. The
nUMberblocks that the •• occupies depends on the device. It
is ere.ted by the utility • ZERO' cOMMand. Only the first 64 words
of each . . block have Man; ng. Each word .aps 16 blocks and 60
W('''• •, . . used for M8I)p i ng. TMrefore th i s "'ap Nill ",ap 960 blocks.
A bit set Means a block is used end a bit is clear when not used.

.-------------------------.
LINK TO NEXT HAP BLOCK !

WORD

--------_._._------------!
MAP NUf1BER
---------_._-------------!
60(10)

- Logical block nuMber of next
.ap block contains zero if
it is the last 1ftaP.
Which ",ap this one is.

NuMber of Nords used for ",ap.

LINK TO FIRST MAP

Logical block nuMber of first
bit ",ap.

Map for 960 blocks.

.
I

... _-------------_._.
! ---MAP FOR BLOCKS 0·15 (10)
i,---------------------_._HAP FOR BLOCKS 16-31(10).
,----------_._-----------_.
·!
!
!

6
Bit set Nhen block is used.
Bit cleared Nhen block free.

!
I •• _______________________ !

·•

.•

!MAP FOR BLOCKS 944-959(10!

•

WORDS 65-255 - NOT USED.

-.-

---> . . . . ~ .--~-..- _ . --..-.... _ - - - - - - - - - - - _ . _ - _. . , -~~-.---------. - - ,

SEQ 0010

Page 9
SEQ 0011

4.1.4

RendoM Access De'" ice Info,.",at ion

------------ .. -------- .. _--------------

DEVICE

!HNEHONIC! 1st

! . of ! 1st
!.
! MFOl ! MF02 !
! UFO
! UFO
! BIT
! OF!
!
!
! BlK • ! Blocks ! MAP BlK ! MAPS !
!
!

!
!

--------)---------}-------}--------}---------)------)------)------)
! 00
!
'5!
4
!
7
!
1 !
1 !
2 !
--------)---------)-------)--------)---------}------)------}------}
AP04 •5.6 ! DB
!
'5! 170. ! 173.
! 50.!
1 !
2 !
--------}---------)-------}--------}---------)------)------}------)
RK03.5 ! OK
!
3!
16 . ! 4795 •
!
5.!
1 ! 4794.!
-----_._)---------)-------)--------)---------)------)------}------}
RlOl/2 ! Ol
!
24.! 146.!
2
! 22.!
1 ! !
lUSt

~--.-~--)---------)-------)--------)---------)------)------)------)
Rt<06.7 ! Df1
!
31.!
96.!
2
! 29.!
1 ! !

-----_ .. )_._------)----_
.. )--------}---------)------}------)------)
! DP
!
3 ! 170. ! 173 .
! 50.!
1 !
2 !

RP02 • '5

--------)---------)-------)--------}---------)------}------}------}
! DR
!
52.! 170.!
2.
! 50.!
1 ! !
--------)---------}-------)--------}---------)------}------)------)
RS03.4 ! OS
!
3!
4
!
7
!
2 !
1 !
2 !
RH03

____ ._._}w _____ • __
1056
! OT
!

)_._.~-.)---M----)---------)------}-

102!

104

_____ }______ }

! 100

! 101

•

--------)-----_
.. _}-------)--_._---)---_._---)------}------}------}
RXOl
! OX
!
3!
4
!
7
!
1 !
1 !
2 !
--------)---------}-------)--------}---------)------}------}------}
RX02
OY
!
3!
16. !
19.
!
4 !
1 !
2 !
--UOA50
.. -... !!}-~--.-..
}---.--.)-- .. ----}---------)------}------}------)
DO
!
35.! 234. ! 269.
! 69.!
1 !
2 !
.. ----~.-)---.. ---)-.-----)---.----)---------)------)------}------}
RORX
! OQ
!
3!
16 . !
19 .
!
4 !
1 !
2 !
--------)----_
....
>-------)--------)---------)------>------}------}
RC25
! OA
!
35.! 181. ! 216.
! 53.!
1 !
2 !
•

•

.---~--~.---~--~--.-------.--------.---------.------.-----_._----_

•

.... _

...._ _

.......... _ . . . . . . . . . . .

_ _ ~..w.

_ _ _ _ _ _ _ _ _ _ _ _. . .- - - .

, -•• - . - - , . , - - - - - - - - - .

Page 10

SEQ 0012

DEVICE ! . OF BLKS ! • OF 9LKS TO ! INTER- ! BOOT ! MONITOR !
ON DEV )! ______________
PREALLOCATE }! ________
lEAVt }! _______
BlK • )_----a-eel
! BLOCK • !
.---- ___ }! ___________
Tusa

511 ~!

40.

8.!

--------)-_._-------}--------------)--------)-------)---------)
48000.
!
255.
!
1
!
0
!
223. !

RP04.S.6!

---_. _._)-----------)._------------}--------)-------)------ __ e)
!
4800.!
69.
!
5
!
0
!
30
!

RKO!.5

--_ .. _--}---------_.)--------------)--------)-------)---------)
! 20460. or!
200.
!
1
0
170.

RLOa

RlO!

10200.

! ! ! !

--------)-----------}--------------)--------)-------}---------)
RK06.7
! 27104.
!
157.
!
1
!
0
!
127. !

._ .... --)! ..48000.
_--------)---_
...
_------)_._-----)-------)---------}
!
255.
!
1
!
0
!
223. !

RPOa.!

--------)-_._-------)._------------)--------)-------}---------}
! 48000.
!
255.
!
1
!
0
!
222. !

RH03

.. ------)---------.-)-~---.--------)--------).------}.--------)
!
989.
!
41.
!
1
!
O!
9.!

RSO!.4

--_ .. _--)_ ... _------) .. _-----------)--------)---_._-}---------)
576.

TUS6

69.

.. _-----)-----------)--------------)--------)-------)-----a-eel
RXOI
!
494.
!
40.
!
1
!
O!
8.!

.. ---.--)-.-~-~-.. -)--------------)-------.)-------}---------)
!
!
55.
!
1
0
!
23.!
9~8.

AX02

-_ ...... )._. __ .. _... )_ ... _---------}--------)-------) ..

_------}

! 65535.
!
338.
!
1
!
O!
3.!
-.-.--.~-)-----------)RDRX
!
790.
!
55 •
!
0
!
0
!
23 . !
----.---)~----------)--------------)--------).------)-----_._.}
RC25
! 50840.
!
269.
!
1
!
O!
3. !
UOA50

.. ---.-------)--------)-------)---------)

•

_iII
__
• _ _ _ _ _ __

-..

_ _ •_ _ _ _ _-

... _... _ _ _

----~---.-----------.--------------.-~------.-------.--------_.

... _,

,. " ... ,_.." ...... ,._..

'N_~,_~

_ _... _ _ , _ _ ..__ .....__..__________. ____ "______

__. __ ._'. . _._

SEQ 0013

Paoe 11
4.2 Se.,.ntial Acces. Devices
-------._----.--------..
4.2
.. 1 I1agt8pe
Altt)ough _ t . i. not usually considered as • file .tructu"e~
*¥ ; ce. ce"tal n stf'uctu"e feiature. a"e i IIPleMnted to enable
c".ation Mel ,..trie¥al of MUlt;ple files.
The fil •• on -..ttPe are terainated by an end-of-fil. .ark (EOF)
or t.. ..rk (lM). The last file on the t . . is teMlinated
by 2 consecutive EOFs to indicate logical-end-of-tape •

-._--

...1ST---------_._---_
..... ------------------------------___ e.
FILE EOF 2ND FILE EOF LAST FILE EOF EOF
!

file on matt. . is -.de up of a heade" and data records .

! HEADER ! IRG ! DATA RECORD ! IRG ! DATA RECORD ! IRG ! EOF ! lAG !
! 7 WORDS !
! 256 WORDS!
! 256 WORDS!
!
!
!

.-------------------------------------------------------_._----------.
The header record is s~ructured a. 'ollows:
WORD
1 - Filen... encoded in RAD-50.
! FILE NAf1E
!
!
!
!---.-.--.-------.~!
! FILE EXTENSION !
!-_ •• _-----_._-----!
!
401
!

2
3

4
!------_
...
_-------! 5
!
0
!

!------------------!
! FILE DATE
!
•·,._------_._._._--•
!
!

FILE SIZE

6
7

... _-------------_.

i.....

- Extension encoded in RAD-50.
. . DOS-11 UIC tl,11
. . Set to zero.
DOS-11 for.at for Date given file
when .ritten on t~. File ia
contiguous if bit 15 of date, is set.
- Nulllber of log i ca t '" '\ oekq (records)
in the file.
e

The first file on. " " " is nor..llv the XXDP. aonitof' core
It is .."itten _ .• COfttiglo.~ file. Every new file is
.... 1tteft .t the lotica1 . . of
The l ..t
Of"
tepe.y
Of..... ,ttlft to part
fter the ""sical EOT ..rkef' bul.. no file
... 11 be ... ittett ent rely .ft.r the _ysical EDT Hrk. The n~r
of fil.s that. caot. . c*' Kco_aAte is • function
the
size, the d.. ive density and ,he tape length.

ti•••

t...

'il.

----------'-

'il,

.......-..~-....-----

..........-

------

~.-....

I
I

Pete 12

e....tt. -...
(TU60)
•........•..••.
_-.

4.2.2

c....tt. i. at"uctu".d .iail."ily to ...tape in th.t .ach file is
.receded br • he"'r aftd a ••
that ldentifi •• the logical .nd
of t... HoNe".r_ the ICtu.l data in the he. ." end .nd-o'-'i Ie

"k."

."St." •.-. d i ft.......t .

f. ,...

The fi1 •• Oft.c....t~••". t.1'ain.te~bI •. 'ile~. Th. l ••t 'ile
t..
,n.ted by • sentlM '.le. A ,.1. gap ....t
OPeCede the fir.t 'i1e on the c....tt•• The tepe is 'or.att.d a.
foIl... :
Oft the

......
-._---_ .. _----------------------------------------------.
! GAP ! FILE A ! GAP ! FILE B ! GAP ! FILE C ! GAP ! SENTINEL !
.. -----.--- .. --.~---.-.-----.---------------------------------.

The sent i~l fa.' i • • 3cr byte record contain ing ell zero's.
ElCh file on cn..tte ;. . . . uP
a , i Ie he. .r r.cord end , i Ie
dlt. ~co"~ in aulti.le.
4•
•...••........... -_ ....•.... _---------._----. __ .- ..... -----------.
! FILE
! DATA
~ OATA
! DATA
! DATA
! GAP !
i HEADER ) RECORD
) RECORD
) RECORD
) RECORD
)
)
! 32 BYTES ! 128 BYTES ! 128 BYTES ! 128 BYTES ! 128 BYTES !
!

The file he~r r.cord is .tructured .s 'ollows:
ByTE
Filen... encoded in RAD-50.
! FILE NA~
! 1·6
1·········_-_······
Extension encoded in RAD-50.
! FILE EXTENSION
1.8.9
1 __ •• --.---_ •••• _-•
. File type indicator.
! FILE TYPE
10
0-6000. 14-Deleted.
• ~- .. ...
...
~ord indicatinl record length set
! 100000
• 11.12
to
100.000 (12 byte reco"ds).
•! ....... _..........
•
...•
Sequence nUMber not used in XXDP •.
!
0
. 13
!
Helder continu.tion not used in
i
0
! 14
XXDP·.
!
!
! .......... __ ...... -_ ...... !
!
! 15.16 .. Not u.ed.
! ..... - .... ---.~- .. !
date for when file
! DATE
! 11.18 . DOS"11 for.et
w•••ut on tape.
!
!
! ................... !
! 19.20 - NUMber of logical blocks in file.
! FILE LENGTH
Qnli ...ningful for contiguous files
•!• ...... - ....................... !••
21.'S2 ~ Not used.

.. - -.-.--

··
•

............. _

...

,...

w_ • •

•
•

· _& .. .,;. a

oil-

0
..

<II

..................

"'"

...

.....

•

........

,-,

...... --..-.....~.~----,--- . ~.

....-.--,.,.---~.- .. ---.--.,

SEQ 0014

C2
Page 13

5.0 GLOSSARY
IRG

- Inte""eco"d ,lIP. The lap that is written bettCeI!n
reco"ds on Magtape.

MFO

- " ••te" File Directory

RAO-50

- RADIX-50. A ..thad
encoding 3 ASCll cha".cters into
one 16 bit MO"d.
User File Directory.
. User Identification Code.

LFO
WIC

_c__ ....

~_.

_________

--.-._.---.-..-._---- ._-- --

SEQ 0015