DEC's 1974 PDP-8 Pocket Reference Card

This is a full reproduction of DEC's pocket reference card copyright 1974 by Digital Equipment Corporation, and reproduced in 1994 with permission by Douglas W. Jones at the University of Iowa Department of Computer Science

An index has been appended at the end of this document, along with notes on the transcription.




pdp8

POCKET REFERENCE CARD


















          |d|i|g|i|t|a|l|


BASIC INSTRUCTIONS


AND      0000  logical AND                         2.6
TAD      1000  2's complement add                  2.6
ISZ      2000  increment and skip if zero          2.6
DCA      3000  deposit and clear AC                2.6
JMS      4000  jump to subroutine                  2.6
JMP      5000  jump                                1.2
IOT      6000  in-out transfer                     ---
OPR      7000  operate                             1.2


 _0___1___2_ _3_ _4_ _5___6___7___8___9___10__11
|           |   |   |                           |
|OP CODE 0-5| IA| MP|          ADDRESS          |
|___|___|___|___|___|___|___|___|___|___|___|___|
              |   | |            PAGE           |
              |   |  --->  RELATIVE ADDRESS <---
              |   |
               ----------- INDIRECT ADDRESSING
                  |         0 = DIRECT
                  |         1 = INDIRECT
                  |
                   ------- MEMORY PAGE
                            0 = PAGE ZERO
                            1 = CURRENT PAGE
            
Memory Reference Instruction Bit Assignments

GROUP 1 OPERATE MICROINSTRUCTIONS (1.2 usec)

                                                Sequence
NOP      7000  no operation                          -
CLA      7200  clear AC                              1
CLL      7100  clear link                            1
CMA      7040  complement AC                         2
CML      7020  complement link                       2
RAR      7010  rotate AC and link right one          4
RAL      7004  rotate AC and link left one           4
RTR      7012  rotate AC and link right two          4
RTL      7006  rotate AC and link left two           4
IAC      7001  increment AC                          3
IAC      7002  swap bytes in AC                      4

GROUP 1
 _0___1___2_ _3_ _4_ _5_ _6_ _7_ _8_ _9_ _10 _11
|           |   |   |   |   |   |RAR|RAL|   |   |
| 1   1   1 | 0 |CLA|CLL|CMA|CML|RTR|RTL| 0 |IAC|
|___|___|___|___|___|___|___|___|___|___|___|___|
                                          |
BSW IF BITS ______________________________|
8 & 9 ARE 0


Logical Sequences:

       1-- CLA, CLL
       2-- CMA, CML
       3-- IAC
       4-- RAR, RAL, RTR, RTL, BSW

Group 1 Operate Instruction Bit Assignments


COPYRIGHT (c)1974 DIGITAL EQUIPMENT CORPORATION


GROUP 2 OPERATE MICROINSTRUCTIONS (1.2 usec)

                                                Sequence
SMA      7500  skip on minus AC                      1
SZA      7440  skip on zero AC                       1
SPA      7510  skip on plus AC                       1
SNA      7450  skip on non-zero AC                   1
SNL      7420  skip on non-zero link                 1
SZL      7430  skip on zero link                     1
SKP      7410  skip unconditionally                  1
OSR      7404  inclusive OR, switch register
               with AC                               3
HLT      7402  halts the program                     3
CLA      7600  clear AC                              2

GROUP 2
 _0___1___2_ _3_ _4_ _5_ _6_ _7_ _8_ _9_ _10 _11
|           |   |   |SMA|SZA|SNL| 0 |   |   |   |
| 1   1   1 | 1 |CLA|SPA|SNA|SZL| 1 |OSR|HLT| 0 |
|___|___|___|___|___|___|___|___|___|___|___|___|

Logical Sequences:

1(Bit 8 is Zero)-- Either SMA or SZA or SNL
1(Bit 8 is One) -- Both SPA and SNA and SZL
       2        -- CLA
       3        -- OSR, HLT

Group 2 Operate Instruction Bit Assignments

COMBINED OPERATE MICROINSTRUCTIONS (1.2usec)

                                                Sequence
CIA      7041  complement and increment AC         2,3
LAS      7604  load AC with switch register        2,3
STL      7120  set link (to 1)                     1,2
GLK      7204  get link (put link in AC bit 11)    1,4
CLA CLL  7300  clear AC and link                   1
CLL RAR  7110  shift positive number one right     1,4
CLL RAL  7104  shift positive number one left      1,4
CLL RTL  7106  clear link, rotate 2 left           1,4
CLL RTR  7112  clear link, rotate 2 right          1,4
SZA CLA  7640  skip if AC=0, then clear AC         1,2
SZA SNL  7460  skip if AC=0, or link is 1, or both 1
SNA CLA  7650  skip if AC/=0, then clear AC        1,2
SMA CLA  7700  skip if AC<0, then clear AC         1,2
SMA SZA  7540  skip if AC<=0                       1
SMA SNL  7520  skip if AC<0 or line is 1, or both  1
SPA SNA  7550  skip if AC>0                        1
SPA SZL  7530  skip if AC>=0 and if the link is 0  1
SPA CLA  7710  skip of AC>=0, then clear AC        1,2
SNA SZL  7470  skip if AC=0 and link=0             1



MQ MICROINSTRUCTIONS (1.2usec)

NOP        7401    no operation
CLA        7601    clear AC
MQL        7421    load MQ from AC then clear AC
MQA        7501    inclusive OR the MQ with the AC
CAM        7621    clear AC and MQ
SWP        7521    swap AC and MQ
ACL        7701    load MQ into AC
CLA, SWP   7721    load AC from MQ then clear MQ


GROUP 2
 _0___1___2_ _3_ _4_ _5_ _6_ _7_ _8_ _9_ _10 _11
|           |   |   |   |   |   |   |   |   |   |
| 1   1   1 | 1 |CLA|MQA|   |MQL|   |   |   | 1 |
|___|___|___|___|___|___|___|___|___|___|___|___|

Logical Sequence:

   1--CLA
   2--MQA, MQL
   3--ALL OTHERS
    
MQ Microinstruction Bit Assignments

TELETYPE KEYBOARD/READER

                                            Time (usec.)
KCF      6030  Clear Keyboard/Reader Flag,          1.2
               do not start Reader
KSF      6031  Skip if Keyboard/Reader Flag = 1     1.2
KCC      6032  Clear AC and Keyboard/Reader         1.2
               Flag, set Reader run
KRS      6034  Read Keyboard/Reader Buffer Static   1.2
KIE      6035  AC 11 to Keyboard/Reader Interrupt   1.2
               Enable F.F.
KRB      6036  Clear AC, Read Keyboard Buffer       1.2
               Clear Keyboard Flags 

TELETYPE TELEPRINTER/PUNCH

SPF      6040  Set Teleprinter/Punch Flag           1.2
TSF      6041  Skip if Teleprinter/Punch Flag = 1   1.2
TCF      6042  Clear Teleprinter/Punch Flag         1.2
TPC      6044  Load Teleprinter/Punch Buffer        1.2
               Select and Print
SPI      6045  Skip if Teletype Interrupt           1.2
TLS      6046  Load Teleprinter/Punch Buffer,       1.2
               Select and Print and Clear
               Teleprinter/Punch Flag

HIGH SPEED PERFORATED TAPE READER--TYPE PR8-E

RPE      6010  Set Interrupt Enable for Reader      1.2
               and Punch
RSF      6011  Skip if Reader Flag = 1              1.2
RRB      6012  Read Reader Buffer and Clear Flag    1.2
RCF      6014  Clear Flag and Buffer and            1.2
               Fetch Character
RCC      6016  Read Reader Buffer, Clear Flag and
               Buffer, and Fetch Character
PCE      6020  Clear interrupt Enable for Reader    1.2
               and Punch


HIGH SPEED PERFORATED TAPE PUNCH TYPE PC03

RPE      6010  Set Interrupt Enable for Reader      1.2
               and Punch
PCE      6020  Clear interrupt Enable for Reader    1.2
               and Punch
PSF      6021  Skip If Punch Flag = 1               1.2
PCF      6022  Clear Flag and Buffer                1.2
PPC      6024  Load Buffer and Punch Character      1.2
PLS      6026  Clear Flag and Buffer, Load          1.2
               Buffer and Punch Character

EXTERNAL IOT MICROINSTRUCTIONS


DECTAPE AND CONTROL TYPE TU56/TC08          Time (usec.)

DTRA     6761  read status register A               2.6
DTCA     6762  clear status register A              2.6
DTXA     6764  load status register A               2.6
DTSF     6771  skip on flags                        2.6
DTRB     6772  read status register B               2.6
DTLB     6774  load status register B               2.6


RANDOM ACCESS DISC FILE TYPE DF32D

DCMA     6601  clear disk memory address            2.6
               register, & disk flags
DMAR     6603  load disk memory address             3.6
               register & read
DMAW     6605  load disk memory address             3.6
               register and write
DCEA     6611  clear disk extended address          2.6
               register and address memory
               extension
DSAC     6612  skip on address confirmed flag       2.6
DEAL     6615  load disk extended address and       3.6
               memory address extension
DEAC     6616  read disk extended address register  3.6
DFSE     6621  skip on zero error flag              2.6
DFSC     6622  skip on data completion flag         2.6
DMAC     6626  read disk memory address register    3.6

INTERNAL IOT MICROINSTRUCTIONS

PROGRAM INTERRUPT AND FLAG (1.2usec.)

SKON     6000  skip if interrupt ON, and turn OFF
ION      6001  turn interrupt ON
IOF      6002  turn interrupt OFF
SRQ      6003  skip interrupt request
GTF      6004  get interrupt flags
RTF      6005  restore interrupt flags
SGT      6006  skip on Greater Than flag
CAF      6007  clear all flags

 _0___1___2_ _3___4___5___6___7___8_ _9___10__11
|           |                       |           |
| 1   1   1 |    DEVICE SELECTION   |    IOT    |
|___|___|___|___|___|___|___|___|___|___|___|___|
                                      |   |   |
GENERATES AN IOP4 PULSE IF A 1 -------    |   |
    "      " IOP2      "       -----------    |
    "      " IOP1      "       ---------------

IOT Instruction Bit Assignments


EXTENDED ARITHMETIC ELEMENT KE8-E (optional)

MODE INSTRUCTIONS

SWAB     7431           switch Mode from A to B
SWBA     7447           switch Mode from B to A

SHIFT INSTRUCTIONS

SCA      7441           logical OR step counter with AC
SCA CLA  7641           step counter to AC
SCL      7403 (Mode A)  step counter load (from memory)
NMI      7411           normalize
SHL      7413           shift left
ASR      7415           arithmetic shift right
LSR      7417           logical shift right
ASC      7403 (Mode B)  AC to step counter

ARITHMETIC INSTRUCTIONS

MUY      7405           multiply
DVI      7407           divide
SAM      7457           subtract AC from MQ

DOUBLE PRECISION INSTRUCTIONS (MODE B)

DLD      7763           double precision load
DST      7445           double precision store
DAD      7443           double precision add
DPIC     7573           double precision increment
DCM      7575           double precision complement
DPSZ     7451           double precision skip if zero

 _0___1___2___3_ _4_ _5___6___7_ _8___9___10 _11
|               |   |           |           |   |
| 1   1   1   1 |CLA|MQA|SCA|MQL| INST CODE | 1 |
|___|___|___|___|___|___|___|___|___|___|___|___|

Logical           1*  2   2   2       3
Sequence                             Instruction Code

 *Except for MQL                     0=No Operation
**Cannot be combined with other EAE  1=SCL
  operations
                                     2=MUY
                                     3=DVI
                                     4=NMI**
                                     5=SHL
                                     6=ASR
                                     7=LSR

EAE MODE B BIT ASSIGNMENTS


 _0___1___2___3_ _4_ _5_ _6_ _7_ _8___9___10 _11
|               |   |   |   |   |           |   |
| 1   1   1   1 |CLA|MBA|   |MQL| INST CODE | 1 |
|___|___|___|___|___|___|___|___|___|___|___|___|

Logical           1*  2       2       3
                                   Instruction Code
  *Except for MQL           Bit 6=0         Bit 6=1
 **Cannot be combined with  0=No Operation  0=SCA
   other EAE operations     1=ACS           1=DAD
***Bits 5 and 7 must be 1   2=MUY           2=DST
                            3=DVI           3=SWBA
                            4=NMI**         4=DPSZ
                            5=SHL           5=DPIC***
                            6=ASR           6=DCM***
                            7=LSR           7=SAM


EAE INSTRUCTION DIFFERENCES


Instruction Mode A Mode B
MUY The next location The next location holds the multiplier holds the address of the multiplier
DVI The next location The next location holds the divisior holds the address of the divisor
SHL The next location The next location LSR holds one less than holds the number ASR the number of shifts. of shifts. (A shift of On right shifts, zero places is legal.) MQ11 is lost. On rights shifts, MQ11 is shifted into the GT flag.

EAE INSTRUCTION TIMES

Mode A


MEM INSTR LONGEST CYCLES TIME CYCLE NOTES
SWAB 1 1.2us 1.2us SWBA 1 1.2 1.2 SCL 2 2.6 1.4 MUY 2 7.4 6.2 DVI 2 7.4 6.2 No overflow
NMI 1 1.5+.3N 8.1 SHL 2 2.6+.3N 8.9* 25-place shift ASR 2 2.6+.3N 8.9* 25-place shift LSR 2 2.6+.3N 8.9* 25-place shift SCA 1 1.2 1.2

Mode B


MEM INSTR LONGEST CYCLES TIME CYCLE NOTES
SWAB 1 1.2us 1.2us SWBA 1 1.2 1.2 ACS 1 1.2 1.2 MUY 3 8.6 6.2 DVI 3 8.6 6.2 No overflow
NMI 1 1.5+.3N 8.1 SHL 2 2.9+.3N 9.2** 25-place shift ASR 2 2.9+.3N 9.2** 25-place shift LSR 2 2.9+.3N 9.2** 25-place shift SCA 1 1.2 1.2
DAD 4 5.2 1.4 DST 4 5.2 1.4 DPSZ 1 1.2 1.2 DPIC 1 1.6 1.6 DCM 1 1.6 1.6 SAM 1 1.2 1.2
*Computed from 1.4+.3N **Computed from 1.7+.3N



                  ____________________

                       Rim Loader
                       (Low Speed)
                     7756/     6032
                     7757/     6031
                     7760/     5357
                     7761/     6036
                     7762/     7106
                     7763/     7006
                     7764/     7510
                     7765/     5357
                     7766/     7006
                     7767/     6031
                     7770/     5367
                     7771/     6034
                     7772/     7420
                     7773/     3776
                     7774/     3376
                     7775/     5356

                  ____________________

                       Rim Loader
                      (High Speed)
                     7756/     6014
                     7757/     6011
                     7760/     5357
                     7761/     6016
                     7762/     7106
                     7763/     7006
                     7764/     7510
                     7765/     5374
                     7766/     7006
                     7767/     6011
                     7770/     5367
                     7771/     6016
                     7772/     7420
                     7773/     3776
                     7774/     3376
                     7775/     5357
                  ____________________








CONTROL CODES

8-bit
ASCII Character
CODE  Name             Remarks

000   null             Ignored in ASCII input.

200   leader/trailer   Leader/trailer code precedes and
                       follows the data portion of binary
                       files.

203   CTRL/C           OS/8 break character, forces return to
                       Keyboard  Monitor, echoed as ^C.

207   BELL             CTRL/G.

211   TAB              CTRL/I, horizontal tabulation.

213   VT               CTRL/K, vertical tabulation.

214   FORM             CTRL/L, form feed.

215   RETURN           Carriage return, generally echoed as
                       carriage return followed by a line feed.

217   CTRL/O           Break Character, used conventionally
                       to suppress Teletype output, echoed
                       as ^O.

225   CTRL/U           Delete current input line, echoed as
                       ^U.

232   CTRL/Z           End-of-File character for all ASCII and
                       binary files (in relocatable binary files
                       CTRL/Z is not a terminator if it occurs
                       before the trailer code).

233   ESD              Escape replaces ALTMODE on some
                       terminals.  Considered equivilant to
                       ALTMODE.

375   ALTMODE          Special break character for Teletype
                       input.

376   PREFIX           PREFIX replaces ALTMODE on some
                       terminals.  Considered equivalent to
                       ALTMODE.

377   RUBOUT           Key is labeled DELETE on some
                       terminals.  Deletes the previous
                       character typed.








CHARACTER CODES

8-bit         DEC 029  DEC 026  Character
ASCII  6-bit  Card     Card     Repre-
Code   Code   Code     Code     sentation  Remarks

240    40     blank    blank               space
241    41     11-8-2   12-8-7    !         exclamation point
242    42     8-7      0-8-5     "         quotation marks
243    43     8-3      0-8-6     #         number sign (10)
244    44     11-8-3   11-8-3    $         dollar sign
245    45     0-8-4    0-8-7     %         percent
246    46     12       11-8-7    &         ampersand
247    47     8-5      8-6       '         apostrophe or acute
                                           accent

250    50     12-8-5   0-8-4     (         opening parenthesis
251    51     11-8-5   12-8-4(1) )         closing parenthesis
252    52     11-8-4   11-8-4    *         asterisk
253    53     12-8-6   12        +         plus
254    54     0-8-3    0-8-3     ,         comma
255    55     11       11        -         minus sign or hyphen
256    56     12-8-3   12-8-3    .         period or decimal point
257    57     0-1      0-1       /         slash

260    60     0        0         0
261    61     1        1         1
262    62     2        2         2
263    63     3        3         3
264    64     4        4         4
265    65     5        5         5
266    66     6        6         6
267    67     7        7         7

270    70     8        8         8
271    71     9        9         9
272    72     8-2      11-8-2    :         colon
273    73     11-8-2   0-8-2     ;         semicolon
274    74     12-8-4   12-8-6    <         less than
275    75     8-6      8-3       =         equals
276    76     0-8-6    11-8-6    >         greater than
277    77     0-8-7    12-8-2    ?         question mark

300    00     8-4      8-4       @         at sign
301    01     12-1     12-1      A
302    02     12-2     12-2      B
303    03     12-3     12-3      C
304    04     12-4     12-4      D
305    05     12-5     12-5      E
306    06     12-6     12-6      F
307    07     12-7     12-7      G








CHARACTER CODES

8-bit         DEC 029  DEC 026  Character
ASCII  6-bit  Card     Card     Repre-
Code   Code   Code     Code     sentation  Remarks

310    10     12-8     12-8      H
311    11     12-9     12-9      I
312    12     11-1     11-1      J
313    13     11-2     11-2      K
314    14     11-3     11-3      L
315    15     11-4     11-4      M
316    16     11-5     11-5      N
317    17     11-6     11-6      O

320    20     11-7     11-7      P
321    21     11-8     11-8      Q
322    22     11-9     11-9      R
323    23     0-2      0-2       S
324    24     0-3      0-3       T
325    25     0-4      0-4       U
326    26     0-5      0-5       V
327    27     0-6      0-6       W

330    30     0-7      0-7       X
331    31     0-8      0-7       Y
332    32     0-9      0-7       Z
333    33     12-8-2(5)11-8-5    [         opening bracket,
                                           SHIFT/K
334    34     11-8-7(6)8-7       /         backslash, SHIFT/L(8)
335    35     0-8-2    12-8-5    ]         closing bracket,
                                           SHIFT/M
336    36     12-8-7(7)8-5       ^         circumflex(2)
337    37     0-8-5(3) 8-2(3)    _         underline(4)(9)

 Footnotes:
 (1) On some DEC 026 Keyboards, this character is graphically
     represented as [].
 (2) On most DEC Teletypes circumflex is replaced by
     up-arrow (^).
 (3) A card containing this code in column 1 with all
     remaining columns blank is an end-of-file card.
 (4) On most DEC teletypes underline is replaced by
     backarrow (<-).
 (5) On some 029 keyboards this character is graphically
     represented as cent sign (c/)
 (6) On some 029 keyboards this character is graphically
     represented as logical not (-).
 (7) On some 029 keyboards this character is graphically
     represented as vertical bar (|).
 (8) On some LP8 line printers, the character diamond ( )
     is printed instead of backslash.
 (9) On some LP8 line printers, the character heart ( )
     is printed instead of underline.
 (10)The number sign on some terminals is replaced by
     pound sign (L).














                     |d|i|g|i|t|a|l|

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Telephone: (617)897-5111. ARIZONA, Phoenix. CALIFORNIA,
Sunnyvale, Santa Ana, Los Angeles, Oakland, San Diego and
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                 PRINTED IN U.S.A. EH 01805 77 08A/T 14  010


Index to DEC's 1974 PDP-8 Pocket Reference Card

BASIC INSTRUCTIONS
GROUP 1 OPERATE MICROINSTRUCTIONS
GROUP 2 OPERATE MICROINSTRUCTIONS
COMBINED OPERATE MICROINSTRUCTIONS
MQ MICROINSTRUCTIONS
TELETYPE KEYBOARD/READER
TELETYPE TELEPRINTER/PUNCH
HIGH SPEED PERFORATED TAPE READER TYPE PR8-E
HIGH SPEED PERFORATED TAPE PUNCH TYPE PP8-E
DECTAPE AND CONTROL TYPE TU56/TC08
RANDOM ACCESS DISK FILE TYPE DF32D
PROGRAM INTERRUPT AND FLAG
EXTENDED ARITHMETIC ELEMENT
EAE MODE B BIT ASSIGNMENTS
EAE INSTRUCTION DIFFERENCES
EAE INSTRUCTION TIMES
RIM LOADER
CONTROL CODES
CHARACTER CODES

Notes

In this reproduction, every effort has been made to preserve the typography of the original, but the results you see may vary depending on your WWW brouser. Page breaks in the original are marked here with double horizontal rules, and the original was printed with black text and brown headings and figures on heavy white paper, using what might have been 6 point News Gothic (a small, light sans-serif font), with all titles and subtitles left justified. The original pages were 3.375" by 7" (8.7 by 18cm), stapled into book form.

The 1974 edition focused on the PDP-8/E instruction set, with figures integrated into the text and coverage of a variety of common peripherals from the early 1970's. Curiously, extended memory addressing instructions are not included in this reference card, and unfortunately, the typos in the original 1965 reference card were reintroduced in the descriptions of the SMA SZA, the SPA SZL and the SPA CLA combined operate microinstructions, along with a new typo on the SNA CLA instruction. These are corrected here.