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May 2000

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Document:	KW12 Seminar
Order Number:	XX-62D3F-E4
Revision:	0
Pages:	36
Original Filename:	http://bitsavers.org/pdf/dec/pdp12/diagnostics_set2/KW12_Seminar.pdf

OCR Text

SALESMEN'S SEMINAR
KW12 .REAL TIME CLOCK

.Introduction
·The KW12 Clock is an exceedingly flexible tool.

The

" following discussion is designed to present a functional "bigpieture" description of the Clock and its features.
Puls~

Generator - counting Rate ·
KW12 has a Variable Time Base.

_,,~

.· '··"

•• selected by prog:r-am control.
~,

External input
400

The counting rate is

100 cps

kc··7
100

kc·~

1 kc

"10 kc

The external input line enables the u·ser to utilize
external events (such-as line frequency) as a time base or to
simply count external events.
The crystal-controlled pulse generator has an accuracy
of .01% at 400 ~c.
Counter Register .
Each generated pulse causes the counter to be incremented
by one.

\ .

- 20

ii)

SALESMEN'S SEMINAR
KW12 . REAL TIME CLOCK

The counter is a 12-bit register and counts up to
7777 8 and then "overflows" on the next pulse.
can be detected by an interrupt,

The overflow flag

skip instruction, . and/or read

status instruction.

· Counter Register
(12-bit Counter)
Overflow
Flag

100 cps

External Input

1 kcs

Note: · Each time the counter reaches 7777 8 + l,
program-detectable ~verf low flag is

the

set~

·Buffer/Preset Register
The buffer/preset register ties the Clock to the PDP-12
accumulator.

It has two functions:

- 21 -

SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK

To read the current contents of the counter into
the AC (to see what "time" it is).

To set the counter to a desired starting value
and allow it to count up from that number to
overflow.
This means that the user may select not only the
pulse generation or counting rate, but may also
determine how many counts will cause a detectable
overflow.
PDP-12 Accumulator

12 bit

Buffer/Preset Register

12 bit

Counter Register

12 bit

·Pulse Generator

The user program can read the counter by loading its
contents into the AC through the buffer/preset register.
The user program can initialize the counter to a start-

•

. ing quantity by loading the counter from the AC through the
buffer/preset register.
\

- 22

SALESMEN'S SEMINAR
KW12 REAL TIME CLCCK

It can now be seen that under program control:
1.

Counting rate is selected.

Counter overflow is detected.

Contents of counter can be transferred to AC.

Counter can be reset to a known value from AC.

·.The question now is how does the program know when it
should read and/or reset the clock counte~.

This depends upon

the status of the real-world events with which the program is
dealing.

External events (pulses) are detected on three input

channels.

(C~.:.

Input Synchronizers

Each of the three input channels incorporates a Schmitt
trigger wi~h pulse generator and associated logic.
The clock control panel allows selection of

Input signal voltage threshold (±°S volt range).

E~ther

positive- or negative-going slope.

+5
-5

When these preselected conditions are met, the input
signal is converted to a program-detectable event.
When such an event
priate action,

occ~,rs,

the program can take appro-

such as reading or resetting the counter,

menting an event tally,

etc.

- 23 -

incre-

SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK

Accumulator

4p.

· Input
C11nnnels
#3

Clock Controller

Buff er/Preset 12
Overf low

·•

•

Counter

li-

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

1 00 cps

400 kc / /

\ " " - 1 kc

100 kc
10 kc
Pulse Generator
Note that external input channels are selected under

program control.

The voltage threshold and signal slope are

selected via the control panel.
-· ·, Input Control Panel

Source
Line Freq
Input 1

+
Output 1

Threshold

SALESMEN'S SEMINAR
KW12 REAL TIME CI,OCK

Jacks·

Input 1 and Output 1 are phone jacks.

The output is

available for daisy-chaining to another input, A/D
converter,
Source

etc.

Input signal slope selection.

Also line voltage

selection for 60-cycle/50-cycle timing or counting.
Threshold

coarse ±s volt selection.
Program control of the clock-includes the use of three

managing registers.
AC
. Clock Control Register
12

Buffer/Preset

#3 ..
.

Clock Enable ~egiste~ ·
12

Overf l ow

Counter

#2 •

#3 •

•

Clock Status Register
12

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

Clock Control Register
This register selects the counting rate and mode of
clock operation.

It is initialized through 8-mode IOT instruc-

tion 6132 - CLLR (Load clock control register from AC).

SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK

1011 !2 I

l 3 141 s I

'--y--/

Ly--'

counting
Rate
Select

Mode
Select

Input Simulation
(For Diagnostic Progranuning)

Counting Rate
AC~..:. 2

trt:'.
~·

000

STOP

001

400 kc

010

100 kc

011

10 kc

100.

1 kc

101

100 cps

i·10

·count from channel 1

111

STOP

Modes of Clock Operation
AC3_5

Free Running Mode - Counter runs at selected rate, and
overflow occurs every 409610 counts.

This mode is

probably not too useful except for producing overflow
"ticks" every (counting rate x 4096) second.
easy to understand
Counting

26 -

,. ......@¥14@

It is

SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK

Free Runnin9' Mode with Preset - Counter runs a' selected
rate, and when overflow occurs,

the contents of the

buff er/preset register are transferred to the counter
and counting continues.

This mode allows for an overflow event to occur at
predetermined time intervals.
The buffer/preset register is usually initialized

~.···

to the negative value (two's compliment) of the numI
• I

ber of· counts desired before overflow .

Note that the overflow flag set in the above two modes remains set
until cleared by IOT instruction 6135.
Event Timing Mode with no resetting.

Counter runs

at selected rate, and on the occurence of an event on
a· selected input channel, the contents of the counter
are transferred to the buffer/preset register and the
counter continues to count.

This mode is useful for

determining the total elapsed time from one initial
event to subsequent events.

SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK

A poststimulus histogram (PST) could be generated
using this mode.

A stimulus could be issued to a

subject and the time to succeeding neuron firings
could be determined
tl
Neuron Firings

+-,--->t
'

Stirn

0'11

t3
Event Timing with Resetting to.Zero - Counter runs
at selected rate.

Events on channels 1 and 2 can

cause the transfer of the counter to the buffer pre'. ' . , . '

... _,,·.

.set register and the counter will continue to count.

An event on channel 3, however, will cause the counter
to be cleared after its contens have been transferred
to the buffer/preset register.
This mode is useful in "restarting" the counter on
one external event, but not on the others.

For the

above example, another stimulus on channel 3 could
cause clearing of counter for timing following neuron
firing with respect to the second stimulus.

It can

also be used to record the time between events.

!!.
'; ,;

. .;.. 28 -

.
.

SALESMEN'S SEMINAR
h'Wl 2 REAL TIME CLOCK

Clock Initiated A/D Conversion

100

000
001

except that the occurrence of

11~

010

overflow will trigger the A/D

111

011

converter if fast-sample

101

are identical to

func~

tion is set.
CLock Enable Register
The "who_ will do it" register
Selects the inputchannels which are ·to be active
·during the program run.
2.

Contrbl.s interrupt enabling for external. events
and overflow flag.·

3.· Allows initializing of counter from buffer/preset

Channel 2
interrupt
enable•
enabl~ ~·· ·

·channel 1·
intern1pt

5-.-,4--1s......J

I GI 1 Is I

t . .

1'
Channel 1

1'.
Tr ans f ~r 1,..c_o_n_t_e_n_t-.s-.-o-f--0...verf low
buffer preset regis- interrupt
enable··
ter to counter (inclusive or) if mode
001 and overflow is ·
cleared.

enable

Channel 3
interrupt
enable

l
l l1tj1if
9

1' . ~·

Channel 2 ·channel 3 ·
enable
enable

This register is loaded from AC by IOT 61~4 CLBN (Load Clock Enable
register).
. . ·. ·:.:··

... ,,

.{'.. •.·::~

. ·"' .':''

29 "."'..
1..

;

SALESMAN'S SEMINAR
KW12 REAL TIME CLOCK

~lock

Status Register
This is the "who done it" register.

When an external

event or overflow occurs, a bit is set in this register and the
entire register is available for program interrogation.

If more than one event occurs before this register is
iead,

another bit is set indicating an event overlap condition.

If the overlap,event is on the same channel

as the first event,

a "pre-event" bit is set.

Event
Channel l

[0I1I2 I

Event
Channel 2

1617181
.J,.

Pre-event
Channel 1

Overflow

Pre-event
Channel 2

Event
Channel 3

(1¥1~
Pre-event
Channel 3

The status register is transferred to the AC with IOT
6135 CLSA (Clock Status to AC) iriclusive or reading the status
register cl,ears all event indicators including the overflow flag.
Clock Handling Instructions (8 Mo l:it:.)
6137

CLCA

Clock Counter to AC
AC cleared first,

then the counter contents

is transferred to the buff er/preset register

th~n

6136

CLBA

to AC.

Buff er Preset to AC
AC cleared first.

30 -

SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK

6133

CLAB

AC to Buff er Preset
AC is unchanged.

Previous contents of

buffer preset are unchanged.
6131

CLSK

Skip on Clock Interrupt
KW12 REAL TIME CLOCK

SUBROUTINE SETUP PACKAGE
{The subroutine described below is contained on the Demo Tape.
It is listed in the DIAL Index as KW12SUB.)
'

Abstract
This package of subroutines contains the necessary fixed

clock enable register,

and the clock counter..

It is emphasized

that this subroutine package is designed to initialize the clock.
Clock interrupts must be handled using the CLSA (6135) instruction.
Requirements
Storage
This package of subroutines uses 137 (octal) or 95 (decimal)
locations.
Location
The first location of this subroutine package should be assembled
into the first location of any 8-mode page with the rest of the
program following in successive locations. The subroutine is preset; to start in location (6000) 8 of bank·~ unless changed by the
user.
.:.. '31 -

..
SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK

Usage
Calling Sequence
This subroutine package has five 8-mode entry points that
are indirectly called as follows:
JMS I .+l
KWxxxx

I Indirect jump to subroutine
I whose location is contained

I in the.location immediately
I following the JMS
In using one of the entry points, the subroutine will look·
for data contaihed in the .third,

fourth,

and fifth locations

following the JMS. · ·rri all cases except where the clock
counter is to be-read, ·the AC and link of the main program
are preserved.
The entry point KWMEASure is used to set up the clock to
measure events or intervals of time •. The working contents

of the clock control register, clock enable register,

and

the number of counts to overflow are specified in the locations
following the JMS as follows:

.+l
.+2

JMS I .+l
KWMEAS
C1C2C3C4

I JMS to,entry point KWMEAS
I clock control register setting

I No. of counts to overflow

.+3
.+4

/ clock enable register setting

.+5

I control returns here

SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK

e
Other entry points are used as follows:

.+l

JMS I .+l
KWSTOP

I
I
I
I
I

Stop the clock but preserve
software control, enable, and
buff er registers
Control returns here with AC and
link preserved

JMS I .+l
KWCONTinue .

I
I
/
I
I

Restart the clock using
the settings contained in the
software registers-.
Control returns here with the AC
and link preserved

JMS I .+l
KW READ

/ Read the clock counter into the AC
/ If overflow has occurred, set ·
/link= l, .otherwise link=¢
/ Control returns here

.+2

.+l
.+2

.+1
.+2

/ In the process of performing the
/ read, the buffer preset register
·'/ is restored to the contents of

KWBUFF.

Examples
The following is a program to ring the Teletype bell 1 time
per second.
Begin, JMS I .+1
KWMEAS
51¢¢
¢144

.¢1¢¢

Check, CLSK
JMP check
CLSA
CIA

/ JMS indirectly to
I loc KWMEAS
I rate = 1¢¢ Hz Mode = l
/ 144 octal or 100 decimal counts
I to overflow
/ interrupt on clock overflow
/ (6131) skip on clock interrupt
/ Wait
/ Clear Clock Flag (6135)
·I Clear AC

- .33 -

SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK

TAD

I Load 207 into AC
I Check Teletype flag

K207

TSF
JMP .-1
TLS
JMP check
K207,

I output AC to Teletype
I Go back and wait for next
·/clock overflow
/ Symbol definition

0207

append KW12 set up subroutine
package

The following is a program that

will ring the Teletype bell

. after counting 60 events on external channel 1.
Begin, JMS I .+l
KWMEAS
610'0'
0'074.

/ JMS indirectly to
/ location KWMEAS
I Rate = chan 1 Mode = 1
/Interrupt after (74) 8 or (60) 10
/ counts
/

I
I
I
I
I

Check, CLSK
JMPCHCK
CLSA
CLA

/
/
/
/

TAD K207
TSF
JMP .-1
TLS
JMP CHECK
K207, 0207

I
I
/

Enable chan 1 input
interrupt on overflow
(6131) skip on clock interrupt
Wait
Clear clock flag (6135)
Clear AC
Load AC with .(207) 8
Test Teletype flag·
Wait
Ring bell
Jump to wait loop
Symbol definition
append KW12 setup subroutine
package

barn
11/25/69
-

4L.

34 -

.4 I

SALESMEN'S SEMINAR
KW12 REAL TIME CLOCK
(_

CO··

6133

CLAB

AC to Buffer Preset
AC is unchanged.

Previous contents of

buffer preset are unchanged.
CLSK

6131

Skip on Clock Interrupt
KW12 RE..Z\.L TI.ME CLOCK
SUBROUTINE SETUP PACKAGE

(The subroutine described below is contained on the Demo Tape.
It is listed in the DIAL Index as KW12SUB.)
Abstract
This package of subroutines contains the necessary fixed
protocol iequired to start the K\'112.

The main program.need only

specify the working settings of the clock control register, the.
clock enable register, and the clock counter.

It is emphasized

that this subroutine package is designed to initialize the clock.
Clock interrupts must be handled using the CLSA (6135) instruction.
~eguirements

Stora9.e
'!'his package of subroutines uses 137 (octal) or 95 (decimal)
locations.
Location
•.

The first location of this subroutine package should be assembl.ed

into the first lcication of any 8-mode page with the rest of the

program follm·ling in successive locations. The subroutine is pre-·

""'.........
)""'

set to start in location. (6000) 8 of bank~ unless changed by the
1

1sor

L.-31. ¥... ¥4. A

¥. J

SALESMEN Is SEMINJ.\R
KW12 REAL TIME CLOCK

(j· ..

\c).
;·

Usage
Calling Sequence

This subroutine package has five 8-mode entry points that
are indirectly called as follows:

JMS I .+l
KWxx xx

/ Indirect jump to subroutine
I whose location is contained
/ in the location inunediately

I following the JMS
In using one of the entry points, the subroutine will look
for data contained in the third, fourth, and fifth locations
following the JMS.

...

In all cases except where the clock

counter is to be read, the AC and link of the main program

are preserved.
The entry point KWMEASure is used to set up the clock to
measure events or intervals of time.

The working contents

of the clock control register, clock enable register, and
the number of counts to overflow are specified in the locations
following the JMS as follows:
JMS I
.+l
.+2

./'" ·,

....:;.:::.-··

.+3
.+4

.+1

I<WMEAS
C1C2C3C4

BUFF
E1E2E3E4

.+s

I JMS to entry point JGV:ME.~S .
I clock control register setting
I No. of counts to overflow
I clock enable register setting

I control returns here

- 32 ... !4SfLAbi,,.4

:;;a:s;;_e

g .·-

. . MA A_ A. X_-,, )$¥.!_.¥UP. $&PM-\4S...f44... ·... ?44A\4l

" SALESMEN s SEMINAR
KW12 REAL TIME CLOCK
I

Other entry points are used as follows:
.+r
.+2

JMS I .+l
KWSTOP
;
I

/
/
/
/
/

Stop the clock but preserve
software control, enable, and
buffer registers
Control ret~rns here with AC and
link preserved

.
.+1

JMS I .+l
l<WCONTinue

I Restart the cloc~ using

·JMS I .+l
l<WREAD

I Read the clock counter into the AC

.+2

.+1
.+2

/ the settings contained in the
/ soft~are registers
/·Control returns here with the AC
/ and link preserved

/ If overflow has occurred, set
/ link = l, otherwise link = ¢
I Control ~eturns here
/ In the process of performing the
/ read, the buff er preset register
/ is restored to the contents of
I l<WBUFF.

Examples
The following is a program to ring the Teletype bell 1 time
per second.

51¢¢
¢144

I JMS indirectly to
I loc KWMEAS
I rate = 1¢§f Hz Mode = 1
I 144 octal or 100 decimal counts

¢1¢¢

I interrupt on clock overflow

Begin, JMS I .+l
l<WMEAS

/ to overflow

Check, CLSK
JMP check
CLSA.
CLA

(6131) skip on clock interrupt
I Wait
/ Clear Clock Flag (6135)
I Clear AC

- 33 -

•

KW12SUBC

KW12, REAL TIME CLOCK, SUBROUTINE SETUP PACKAGE

G·
1.0

ABSTRACT

This package of subroutines contains the necessary fixed protocol
required to start the KW12.

The main program need only specify

the working settings of the clock control register, the clock enable register, and the buffer register.

It is emphasized that this

subroutine package is designed to initialize the clock.

Clock in-

terrupts must be handled using the CLSA (6135) instruction.
2.0

REQUIREMENTS

2.1

STORAGE

137 octal or 95 decimal locations are used by the KW12 subroutine
•.

package.
2.2

Location

The first location of this subroutine package should be assembled
into the first location of any 8-mode page with the rest of the
program following in successive locations.

The subroutine is preset

to start in location 6000 8 of bank ¢ unless changed by the user.
2.3

Equipment

Basic PDP-12A or B with KW12 option.

KW12SUBC-l

3.0

USAGE

3.1

Calling Sequence

This subroutine has five 8-mode entry points that are indirectly
called, as follows:
JMS

I .+l

KWxx xx

/INDIRECT JUMP TO SUBROUTINE
/WHOSE LOCATION IS CONTAINED
/IN THE LOCATION IMMEDIATELY
/FOLLOWING THE JMS

In using one of the entry points, the subroutine will look for
data contained in the third, fourth, and fifth locations following the JMS.

In all cases, except where the clock counter is to

be read, the AC and link of the main program are preserved.
4.0

DESCRIPTION

4.1

Discussion

The entry point KWM.EASure is used to set up the clock to measure
events or intervals of time.

The working contents of the clock

control register, clock enable register, and the number of counts
to overflow are specified in the locations following the JMS as
follows:

·~

:;;_

•

JMS I .-rl

.-rl

K\\TMEAS

• -r-3

~fl~~C3C4

.-r2

.-t4
.+5

/JMS TO ENTRY POINT KWMEAS
/CLOCK CONTROL REGISTER SETTING
/NO. OF COUNTS TO OVERFLOW
/CLOCK ENABLE REGISTER SETTING
/CONTROL RETURNS HERE

E1E2E3E4

The first two octal digits of the control register setting control
the rate and mode of the clock respectively.

The last two digits

are used to simulate inputs from the external channels.

The inter-

pretation of c 1 is as follows:
C1

Rate

STOP

400 KHz

100 KHz

10 KHz

1 KHz

100 Hz

Count occurrences of events on external channel 1
if E3 2.

KW12SUBC-3
. Ai _,.it

.. E44

. . MM#

±; . . . . . ¥SU\. . . .44;. .%1., 4:. ;.

The interpretation of C2

the mode control, is as follows:

: C2

Mode

'¢

Counter runs at selected rate and overflow is set after 4096
counts. The counter continues.to run and the overflow must be
cleared by the IOT 6135.

Counter runs at selected rate. Upon occurrence of overflow
caused by the most significant bit of the counter going from
1 to ¢, the contents of the buffer preset register is transferred to the counter.

counter runs at selected rate. Upon occurrence of an event .
on an enabled channel, the· contents of the counter are transferred to the buffer preset register and the counter continues
to run.

Counter runs at selected rate. upon occurrence of an input
event on channel 3, the contents of the counter is transferred to the buffer preset register· and the counter is
reset to ¢ from which it continues counting. Inputs on
channels l and 2 behave as if c 2 ;:2 •

! •

·~

. ·{

. l
•..

,
.'

KW12SUBC-4

The counter runs at the selected rate and overflows every
4096 counts. Upon the occurrence of an overflow, an A/D
conversion is initiated if the fast sample mode is in use.
overflow must be cleared by the 6135 instruction. Note
that when in this mode A/D conversions are inhibited unless
a clock overflow occurs.

This is treated as the combination of
(C2:::: 4)
and (c 2 == l)

(c 2 ::: 4)

and (c 2 ::::. 2)

BUFF is an octal number from 1 - 77779 and is the number of
desired counts to occur before the counter overflows.

The

subroutine places the 2's complement of BUFF in the buffer
preset register and initially in the counter.
.,

t
The last 3 digits of the enable register setting are interpreted

as follows:

KW12SUBC-5

Function
0,2,4,6

No Function

1,3,5,7

Cause clock interrupt on counter overflow.

KW12SUBC-6

. Upon entering the KW12 setup subroutine package at point KWMEASure,
the subroutine retrieves the locations • 2, • 3, and • 4, considering the location (.) to be the locations of the JMS I • 1.

"·

The

contents of these locations are stored.in software created control
(KWCONR), enable (KWENAB), and buffer registers (KWBUFF).
the clock is set up to perform the specified tasks.

Then

Control is

returned to location • 5 with the AC and link preserved and the
'
clock
running.

Other entry points are used as follows:
JMS I .-+l
KW STOP

•
.+l

/CONTROL RETURNS HERE WITH AC
/AND LINK PRESERVED

.+2
:...

/STOP THE CLOCK BUT PRESERVE
/SOFTWARE CONTROL, ENABLE, AND
/BUFFER REGISTERS

... ,:

•
•+l

JMS I .-f'l
KWCONTine

/RESTART THE CLOCK USING
/THE SETTINGS CONTAINED IN
/THE SOFTWARE REGISTERS
/CONTROL RETURNS HERE WITH
/THE AC AND LINK PRESERVED

JMS I .+l
KWREAD

/READ THE CLOCK COUNTER INTO
/THE AC. IF OVERFLOW HAS
/OCCURRED, SET LINK:. 1,
/OTHERWISE LINK= }d
/CONTROL RETURNS HERE

.+2

•
.+1

«.

.+2

/IN THE PROCESS OF PERFORMING
/THE READ, THE BUFFER PRESET
/REGISTER IS RESTORED TO THE
/CONTENTS OF KWBUFF •
. /

.·:.

,,.,,,

·..:~~

KW12SUBC-7
•:!!£

. gggg4$!IL4 .

.: tJ. 44¢is:ti; . .

•

.+l

/INITIALIZES THE CLOCK AND
/CLEARS SOFTWARE CONTROL, /ENABLE, AND BUFFER REGISTERS.
/CONTROL RETURNS TO MAIN
/PROGRAM HERE WITH AC AND
/LINK PRESERVED.

JMS I .+l
KWINIT

• .,..2

EXAMPLES

4.2

The following is- a program to ring the Teletype
bell l time per second:

¢1¢¢

/JMS INDIRECTLY TO
/LOC KWMEAS
/RATE ::. 1¢¢ Hz, MODE = 1
/144 OCTAL or 1¢¢ DECIMAL COUNTS
/TO OVERFLOW.
/INTERRUPT ON CLOCK OVERFLOW

CHECK, CLSK
JMP CHECK
CLSA
CLA
TAD K207

/(6131) SKIP ON CLOCK INTERRUPT
/wAIT
/CLEAR CLOCK FLAG (6135)
/CLEAR AC
/LOAD 207 INTO AC

BEGIN, JMS I .-rl
KWMEAS
51¢¢
¢144
.·

...

..
: ~

·.:

J
··"'l

···~

,,.. ··::·-"' .

KW12SUBC-8
,•

-···.-·-.-t

e:;xz;;. n .• 4.J.w-

TSF
JMP
TLS
JMP

/CHECK TELETYPE FLAG

.-1

CHECK

/OUTPUT AC TO TELETYPE
/GO BACK AND WAIT FOR NEXT
/CLOCK OVERFLOW
/SYMBOL DEFINITION

K207,

0207

/APPEND KW12 SETUP SUBROUTINE
/PACKAGE

The following is a program that will ring the Teletype bell

after counting 60 events on external channel l:
BEGIN,

JMS I
KWMEAS

/Jt.1S INDIRECTLY TO
/LOCATION KWr-'lEAS
/RATE= CHAN 1, MODE = 1
/INTERRUPT AFTER (74) 8 or
I (60) 10 COUNTS
/ENABLE CHAN 1 INPUT
/INTERRUPT ON OVERFLOW

.+l

61¢¢
¢¢74
¢12¢

KW12SUBC-9
•

> -:. ·....

i ....

@@¢!

-•

CHECK, CLSK

JMP CHECK
CLSA
CLA
TAD K207
TSF
JMP

.-1

TLS
JMP CHECK
K207, 0207

/(6131) SKIP ON CLOCK INTERRUPT
/WAIT
/CLEAR CLOCK FLAG (6135)
/CLEAR AC
/LOAD AC WITH (207)
/TEST TELETYPE FLAGS
/WAIT
/RING BELL
/JUMP TO WAIT LOOP
/SYMBOL DEFINITION
/APPEND KWl2 SETUP SUBROUTINE
/PACKAGE

KW12SUBC-10

.DFRQANA or FRQANA
Original Author:

A. M. Engebretson

IJ1ified to run under the PDP-12 DEMO Monitor by: Jerre Caputo,
DEC, Washington, D. c .

. ~sTn~cT-

1(\

ff' \'\ t,1

~-OCJl:aut,

performs frequency analysis resulting in sixty-four

component cosine, sine, and rms spectra.
displays can be scaled;
~rformed

Data. and spectrum

visually the accuracy of the analysis.

RETRIEVE DATA
(2 BLOCKS)

STARTING AT BLOCK
UNIT

'·., h'A o1_-T'.Jr-D....

~r JYPeS' the/firs~ of t~? c~msecutive LINCtape blocks to
--· ,,,.\ w~···tr '"'L"" IZ£ 1 u R._.J ~- 1r ..

be analyzedv)' Uading zeros must be typed., and Ute bteek nuttt~

-:-tnast be

£oll.sw~y~-ing_,tha-,.RE-TURN<~key·;.~

The user then

types the tape unit number to be read, 0 - 7, followed by f'tof...A

Ii'<~

LINEFEED.

~nthesis -of. ., the original data ~, (µ_.., p.A)/y.=ti C'/.i,4_\.o

from the sine and cosine components to check

\)../1 ,....

•

The two blocks specified are read in and displayed.
'\ .:--.. r;::"J
CCV,,0
.
data I may then be scaled -hnger by typing L to increase

a
•rb

FRQANA-1
&1#4414$-

.&it.... """.-·.

A . AP?,_.,._.; ..._zp._ .... .J$tl!($44U,¢ ... Jt.4_. 4~, .....4@. .......c."1@¥®\ __ _

the vertical scale by 50

9=1e vertical scale by 50
~

To perfoxm the

frequency analysis, tl:le l:lser-type~ F.

When

the analysis is complete, the display will reappear according
to which display option previously has been chosen.

Display

options are summarized in Table 1.
/

To compute the resynthesized waveform from the frequency
components,

type1 T.

A9ain, the display will reappear

according to the display option that had been chosen.

Whe~b&.

.~~splay option is I, Sol:- input data, the second trace 'l.~i:l-be J...S
the resynthesized waveform.

The input data can be compared

with t~e resynthesized waveform by turning /.nob 1.

Knob 1 is

trace separ. a·.to~,, affectin.~ only the vertical display of the

•

~- \l. . \l.1i 't'l 1) \.:.~ 'tJ_J..t.,;l -~-J.,......,

data.

Whe~fully counterclockwise; the top trace is the original

data.
·;.

At any time. dut.ing operation, a different display may be

selected by typing the appropriate key.

To select the input

data and resynthesized waveform display, the user types I.

This

is the display that appears immediately after program start or
restart.

FRQANA-2
.·-: ;_-;

....

. .. A..

..n

""·--rt,. .fU C.Ol't·..

i) i ·'"

rv th) ! ),.)1../.'.l

--rei

~eype..s c,.j-ih~- frequency component displayt appear$.
.
•
/;,,

. t h the cosine components on the left and the sine components
on the right.will appear..

These can be scaled using /nob 2.

To select an rms spectrum for display, type P.

This display

~~sohs~i~ by Khob
2.
'
0-

Each bar in the graph of the components and the rms spectr-tmr
represents a single frequency component from l to 64, i.e., the
first bar is the component for the l cycle signal generator and
the third bar is the component for the 3 cycle signal generatorp
etc., up'through 64.

The absolute frequency of the analyzed

waveform components can only be obtained by taking the time
period . represented by the 512 data points sampled: this will
1

9ry depending on the sampling rate used to collect the data.
If the sampling rate were 512 pts./sec. when the data was

- ~ represen-g; the absolute
taken, then each bar of the graph....wonld
components of the frequency domains 1 through 64.

If the rate

were 1024 pts./sec., then the bars ~GuM· represent5£requencies
2,4 ••• 128 cps.

I..

If,·. at any time, the user wishes to select new input data

for analysis, he simply types R to

~~;~0-}£~~.f· 1 ocJ \.tVt

FRQANA-3

1" -

J1.
~KNOB

COMMANDS

~
·Knob 1

Trace separator (original data and resynthesized

Knob 2

Modify spectrum scale

data)

TELETYPE COMMANIB
F

- Generate ~ourier Coefficients

- ~esynthesize F\.;<~~

~data ~a~le;r ~;y lnrlf

f:;IJ!().1~
- .Merke' data larger by half

.
\!'
- Display ~wer spectrum

- Display sine and cosine ~omponents
Display ~put data (and resynthesized data if T
has been typed)

e
'PR

~\6 \A t~~\V

-\l~~trieve· data from tape

·>.

RAM OPE.a.ION

FRQ NA unler 'he DEMO

,~~.r. relies he.aVlJ:~n overlay~pabilities
'

;(

and uses: DEMO Monitor comrnan"ds RETV x(OPR 5}

blo k fbmber o
key

vrd

o obtain the

FR ~NA and OK~PR 12) and :KBD./(OPR 15) to handle

commands.

When FRQANA is loaded under the DEMO Monitor, an attempt is made to
load blocks containing cosine tables into the second 4K of core.
If there is no second 4K, the load is not completed: this will
not affect program operation.

The program starts at LINC

location 20 and control is immed.iately transferred to code in
LINC segment 2 to set up data retrieval procedures for later
4l.erlays.

FRQANA:..4
..

·-EM-·-~-·

... #

- '"

,, ... .,..,,, ....

__ L _ ._ .P. ;:...

. (IL.

·. to query the user concerning data blocks to be analyzed.

This

code is assembled in the same segment as DEMO Summary and Help
Text, and the two tape blocks containing this data (blocks 4

'1a

5, Table 4) are transferred directly to the help frame

blocks used by the DEMO Monitor and stored as source files.
Immediately after Line Feed is pressed in the QANDA routine,
LINC segments 2 and 3 of the program are overlaid with input
data and cosine tables.

The program then begins operation,

as described in the USAGE section.
Whenever R is typed, LINC segments 2 and 3 are overlaid with
· QANDA and text to query the user.

The commands to do this

are the same as those used during program initialization.
Memory allocations at query time and at run time are described

j1 Tables 2 and 3. To avoid confusion and illustrate the
· complete contents of core, both LINC segments and PDP-8 absolute
. addresses are given.
.\Table 4.

Tape block allocation is illustrated in

The block numbers listed are relative to the starting

·block number on tape.
WARNING
:The name of the program, .DFRQANA, is specified in the retrieve

·t file set up in relative block number 5 at location 334 of FRQANA •
"'

: t

•

FRQANA-5

If the name under the DEMO Monitor is changed, then this
tape block must be changed also.
TABLE 2
MEMORY ALLOCATION AT QUERY TIME

LINC Segment

MemBlks

0-l

0-7

0-l~

4000-4577

Program

1-3

4600-5777

Unused core

6000-6377

Program summary text,
help text

6400-6777

Help text, retrieve
data text, code to
handle subsequent
overlays

3-4

7000-7777

QANDA and code to
display text, decode
answers

•

PDP-8
Location

Contents

0-3777

DEMO Monitor

.,.,

FRQANA-6

,,_-'."
.. i
t.

a ·-· ... ..

t ...... :. .. L

...4

;,..; ... _.. uw..J _rate_;.

ht.@.

±.- _ ~
m

.,i..;ijt -•

L !~

----A ....

MemBlks

PDP-8
Location

Contents

0-1

0-7

0-3777

DEMO Monitor

0-l!a

4000-4577

Program

4600-46771

Sine spectrum

4700-4777 1

Cosine spectrum

2-3

5000-5777

Synthesized time
function

0-1

6000-6777

Input data

2-3

7000-7777

Cosine table

Gr.INC Segment

Note that each section is 64 words long, i.e., each word in

the sine table contains the value of the sine component
~ssociated with

a frequency component and likewise for the

cosine component table.

After F has been typed, these tables
are filled with sine and cosine data representing the phase
angle and amplitude of the 64 signal generators.

These 64

generators, when run out mathematically as in the FOURIER
series computation, will regenerate the original data almost
as accurately as when it was taken.

The way to produce a notch

filter effect then would be to attenuate to zero whichever of
0

the sine-cosine components representing the frequency genera-

tor are to be removed from the signal, e.g. to remove 60 cycle
from the signal zero the 60th sine and cosine component of core
from the console using the switch registers and deposit key.

-The above example assumes 512 pt/sec. sample rate at data taking
time.
FRQANA-7

.~
.

-- . .!

· · ;

400

@ .,-,, ... , \_ ,,T . __ .. VU .... . W

.Af\91f#, ....Lo·¥Ab ..._/;;tt?(_.§A? .k. M. )! - l!JA.4-4.#,.Ak. it-. M!.P~ ... -,,,.. ~ ...

... J_,___

£__

Q______

___4\!;tQjZ:S~&.(1@4AJA$$_,..,K_4,lif"'

Relative Block No.

Contents

Residence in Core

Standard DIAL
header block

Never gets to core

FRQANA

4000-4377

FRQANA

4400-4777

Summary-Help 1

6000-6377

Help 2 - Retrieve

6400-6777

QANDA

7000-7377

QANDA

7400-7777

Cosine Table

10000-10377

Cosine Table

10400-10777

f
I

l
f

I
!

FRQANA-8