IBM 709 Programmers Model

The IBM 709 had several programmer accessable registers.

The machine use signed magnitude arithmetic, so S bit was sign.

IBM 709 Registers

All memory was access as full word.

Floating point has the following format, characteristic (exponent) is +128.
IBM 709 Floating Pointer

Instructions as coded one of the following types:

Type A

IBM 709 Type A Instruction Format

Type B

IBM 709 Type B Instruction Format

Type C

IBM 709 Type C Instruction Format

The opcodes decode as follows:

OctalOPTypeNameNotes
 0 36100 t aaaaaACLB ADD AND CARRY LOGICAL WORD 
 0 40000 t aaaaaADDB ADD 
 0 40100 t aaaaaADMB ADD MAGNITUDE 
 0 76700 t aaaaaALSE ACCUMULATOR LEFT SHIFT 
-0 32000 t aaaaaANAB AND TO ACCUMULATOR 
 0 32000 t aaaaaANSB AND TO STORAGE 
 0 76700 t aaaaaARSE ACCUMULATOR RIGHT SHIFT 
-0 77400 t aaaaaAXCE ADDRESS TO INDEX, COMPLEMENTED 
 0 77400 t aaaaaAXTE ADDRESS TO INDEX, TRUE 
-0 76400 t aaaaaBSFB BACKSPACE FILE 
 0 76400 t aaaaaBSRD BACKSPACE RECORD 
 0 76000 0 01000BTTAE BEGINNING OF TAPE TEST, CHANNEL A 
 0 76000 0 02000BTTBE BEGINNING OF TAPE TEST, CHANNEL B 
 0 76000 0 03000BTTCE BEGINNING OF TAPE TEST, CHANNEL C 
 0 76000 0 04000BTTDE BEGINNING OF TAPE TEST, CHANNEL D 
 0 76000 0 05000BTTEE BEGINNING OF TAPE TEST, CHANNEL E 
 0 76000 0 06000BTTFE BEGINNING OF TAPE TEST, CHANNEL F 
 0 76000 0 07000BTTGE BEGINNING OF TAPE TEST, CHANNEL G  
 0 76000 0 10000BTTHE BEGINNING OF TAPE TEST, CHANNEL H 
-0 70000 t aaaaaCADB COPY, ADD AND CARRY 
-0 50000 t aaaaaCALB CLEAR AND ADD LOGICAL 
-0 11400 t aaaaaCAQC CONVERT BY ADDITION FROM MQ 
 0 34000 t aaaaaCASB COMPARE ACCUMULATOR WITH STORAGE 
 0 76000 0 00002CHSE CHANGE SIGN 
 0 50000 t aaaaaCLAB CLEAR AND ADD 
 0 76000 0 00001CLME CLEAR MAGNITUDE 
 0 50200 t aaaaaCLSB CLEAR AND SUBTRACT 
 0 76000 0 00006COME COMPLEMENT MAGNITUDE 
-0 15400 t aaaaaCRQC CONVERT BY REPLACEMENT FROM MQ 
 0 70000 t aaaaaCPYB COPY 
 0 11400 t aaaaaCVRC CONVERT BY REPLACEMENT FROM AC 
 0 76000 0 00012DCTE DIVIDE CHECK TEST 
 0 30100 t aaaaaDFADB
 0 22000 t aaaaaDVHB DIVIDE OR HALT 
 0 22100 t aaaaaDVPB DIVIDE OR PROCEED 
 0 67100 t aaaaaEADB EXTENDED ADDRPQ
 0 56100 t aaaaaECAB EXCHANGE LOGICAL ACCUMULATOR WITH STORAGERPQ
 0 67200 t aaaaaEDPB EXTENDED DIVIDE OR PROCEEDRPQ
-0 76000 0 00006ECTME ENTER COPY TRAP MODE 
-0 76000 0 00002EFTME ENTER FLOATING TRAP MODE 
 0 67000 t aaaaaELDB EXTENDED LOADRPQ
 0 67300 t aaaaaEMPB EXTENDED MULTIPLYRPQ
 0 56400 t aaaaaENBB ENABLE FROM STORAGE 
 0 76000 0 00004ENKE ENTER KEYS 
 0 32200 t aaaaaERAB EXCLUSIVE OR TO ACCUMULATOR 
-0 56100 t aaaaaECQB EXCHANGE MQ WITH STORAGERPQ
-0 67100 t aaaaaESBB EXTENDED SUBTRACTRPQ
-0 76100 0 00140ESME ENTER SIGNIFICANCE MODERPQ
-0 02100 t aaaaaESNTB ENTER STORAGE NULLIFICATION MODE AND TRANSFER 
-0 67300 t aaaaaESTB EXTENDED STORERPQ
-0 76000 0 00005ESTME ENTER SELECT TRAP MODE 
 0 76000 0 00007ETME ENTER TRAPPING MODE 
-0 76000 0 01000ETTAE END OF TAPE TEST, CHANNEL A 
-0 76000 0 02000ETTBE END OF TAPE TEST, CHANNEL B 
-0 76000 0 03000ETTCE END OF TAPE TEST, CHANNEL C 
-0 76000 0 04000ETTDE END OF TAPE TEST, CHANNEL D 
-0 76000 0 05000ETTEE END OF TAPE TEST, CHANNEL E 
-0 76000 0 07000ETTFE END OF TAPE TEST, CHANNEL F 
-0 76000 0 07000ETTGE END OF TAPE TEST, CHANNEL G 
-0 76000 0 10000ETTHE END OF TAPE TEST, CHANNEL H 
-0 76000 0 00011ETTE END OF TAPE TEST 
-0 67200 t aaaaaEUAB EXTENDED UNNORMALIZED ADDRPQ
 0 24000 t aaaaaFDHB FLOATING DIVIDE OR HALT 
 0 24100 t aaaaaFDPB FLOATING DIVIDE OR PROCEED 
 0 30000 t aaaaaFADB FLOATING ADD 
 0 30400 t aaaaaFAMB FLOATING ADD MAGNITUDE 
 0 26000 t aaaaaFMPB FLOATING MULTIPLY 
 0 76000 0 00011FRNE FLOATING ROUND 
 0 30200 t aaaaaFSBB FLOATING SUBTRACT 
 0 30600 t aaaaaFSMB FLOATING SUBTRACT MAGNITUDE 
 0 42000 t aaaaaHPRG HALT AND PROCEED 
 0 00000 t aaaaaHTRB HALT AND TRANSFER 
 0 04100 t aaaaaIIAG INVERT INDICATORS FROM ACCUMULATOR
-0 05100 t aaaaaIILG INVERT INDICATORS OF LEFT HALF
 0 05100 t aaaaaIIRG INVERT INDICATORS OF RIGHT HALF
 0 44000 t aaaaaIISB INVERT INDICATORS FROM STORAGE
 0 76000 0 00005IOTE INPUT OUTPUT CHECK TEST 
 0 53500 t aaaaaLACE LOAD INDEX FROM ADDRESS, COMPLEMENTED 
-0 34000 t aaaaaLASB LOGICAL COMPARE ACCUMULATOR WITH STORAGE 
 0 76000 0 00001LBTE LOW ORDER BIT TEST 
 0 54400 t aaaaaLCHAB LOAD CHANNEL A 
-0 54400 t aaaaaLCHBB LOAD CHANNEL B 
 0 54500 t aaaaaLCHCB LOAD CHANNEL C 
-0 54500 t aaaaaLCHDB LOAD CHANNEL D 
 0 54600 t aaaaaLCHEB LOAD CHANNEL E 
-0 54600 t aaaaaLCHFB LOAD CHANNEL F 
 0 54700 t aaaaaLCHGB LOAD CHANNEL G 
-0 54700 t aaaaaLCHHB LOAD CHANNEL H 
 0 46000 t aaaaaLDAB LOCATE DRUM ADDRESS 
-0 53500 t aaaaaLDCE LOAD INDEX FROM DECREMENT, COMPLEMENTED 
 0 44100 t aaaaaLDIB LOAD INDICATORS
 0 56000 t aaaaaLDQB LOAD MQ 
-0 05400 t aaaaaLFTG LEFT HALF INDICATORS OFF TEST
-0 76000 0 00004LFTME LEAVE FLOATING POINT TRAP MODE 
-0 76300 t aaaaaLGLE LOGICAL LEFT SHIFT 
-0 76500 t aaaaaLGRE LOGICAL RIGHT SHIFT 
 0 76300 t aaaaaLLSE LONG LEFT SHIFT 
-0 05600 t aaaaaLNTG LEFT HALF INDICATORS ON TEST 
-0 76000 0 00010LSNME LEAVE STORAGE NULLIFICATION MODE 
 0 76500 t aaaaaLRSE LONG RIGHT SHIFT 
-0 76000 0 00007LTME LEAVE TRAPPING MODE 
 0 53400 t aaaaaLXAE LOAD INDEX FROM ADDRESS 
-0 53400 t aaaaaLXDE LOAD INDEX FROM DECREMENT 
 0 20000 t aaaaaMPYB MULTIPLY 
-0 20000 t aaaaaMPRB MULTIPLY AND ROUND 
-0 76000 0 00000MSEE MINUS SENSE 
 0 76100 t aaaaaNOPG NO OPERATION 
-0 52000 t aaaaaNZTB STORAGE NON-ZERO TEST 
 0 04300 t aaaaaOAIG OR ACCUMULATOR TO INDICATORS
 0 44400 t aaaaaOFTB OFF TEST FOR INDICATORS
 0 44600 t aaaaaONTB ON TEST FOR INDICATORS
-0 50100 t aaaaaORAB OR TO ACCUMULATOR 
-0 60200 t aaaaaORSB OR TO STORAGE 
 0 44200 t aaaaaOSIB OR STORAGE TO INDICATORS
 0 73700 t aaaaaPACE PLACE ADDRESS IN INDEX, COMPLEMENTED 
 0 04400 t aaaaaPAIG PLACE ADDRESS IN INDICATORS
 0 73400 t aaaaaPAXE PLACE ADDRESS IN INDEX 
-0 76000 0 00001PBTE P BIT TEST 
 0 75600 t aaaaaPCAE PLACE COMPLIMENT OF INDEX IN ADDRESS 
-0 75600 t aaaaaPCDE PLACE DECREMENT IN INDEX, COMPLEMENTED 
-0 73700 t aaaaaPDCE PLACE COMPLEMENT OF INDEX IN DECREMENT 
-0 73400 t aaaaaPDXE PLACE DECREMENT IN INDEX 
-0 04600 t aaaaaPIAG PLACE INDICATORS IN ACCUMULATOR
 0 76000 0 00000PSEE PLUS SENSE 
 0 75400 t aaaaaPXAE PLACE INDEX IN ADDRESS 
-0 75400 t aaaaaPXDE PLACE INDEX IN DECREMENT 
 0 76000 0 00014RCTE RESET CHANNEL TRAPS 
 0 76000 0 01352RDCAE RESET DATA CHANNEL A 
 0 76000 0 02352RDCBE RESET DATA CHANNEL B 
 0 76000 0 03352RDCCE RESET DATA CHANNEL C 
 0 76000 0 04352RDCDE RESET DATA CHANNEL D 
 0 76000 0 05352RDCEE RESET DATA CHANNEL E 
 0 76000 0 06352RDCFE RESET DATA CHANNEL F 
 0 76000 0 07352RDCGE RESET DATA CHANNEL G 
 0 76000 0 10352RDCHE RESET DATA CHANNEL H 
 0 76200 t aaaaaRDSD READ SELECT 
 0 05400 t aaaaaRFTG RIGHT HALF INDICATORS OFF TEST
 0 77200 t aaaaaREWD REWIND TAPE 
-0 04200 t aaaaaRIAG RESET INDICATORS FROM ACCUMULATOR 
 0 76000 0 01350RICAE RESET CHANNEL A 
 0 76000 0 02350RICBE RESET CHANNEL B 
 0 76000 0 03350RICCE RESET CHANNEL C 
 0 76000 0 04350RICDE RESET CHANNEL D 
 0 76000 0 05350RICEE RESET CHANNEL E 
 0 76000 0 06350RICFE RESET CHANNEL F 
 0 76000 0 07350RICGE RESET CHANNEL G 
 0 76000 0 10350RICHE RESET CHANNEL H 
-0 05700 t aaaaaRILG RESET INDICATORS OF LEFT HALF
 0 05700 t aaaaaRIRG RESET INDICATORS OF RIGHT HALF
 0 44500 t aaaaaRISB RESET INDICATORS FROM STORAGE
 0 76000 0 00010RNDE ROUND 
 0 05600 t aaaaaRNTG RIGHT HALF INDICATORS ON TEST
-0 76100 t aaaaaRPQB RESERVED INSTRUCTION 
-0 77300 t aaaaaRQLE ROTATE MQ LEFT 
 0 54000 t aaaaaRCHAB RESET AND LOAD CHANNEL A 
-0 54000 t aaaaaRCHBB RESET AND LOAD CHANNEL B 
 0 54100 t aaaaaRCHCB RESET AND LOAD CHANNEL C 
-0 54100 t aaaaaRCDB RESET AND LOAD CHANNEL D 
 0 54200 t aaaaaRCHEB RESET AND LOAD CHANNEL E 
-0 54200 t aaaaaRCHFB RESET AND LOAD CHANNEL F 
 0 54300 t aaaaaRCHGB RESET AND LOAD CHANNEL G 
-0 54300 t aaaaaRCHHB RESET AND LOAD CHANNEL H 
 0 54000 t aaaaaRSCAB RESET AND START CHANNEL A 
-0 54000 t aaaaaRSCBB RESET AND START CHANNEL B 
 0 54100 t aaaaaRSCCB RESET AND START CHANNEL C 
-0 54100 t aaaaaRSCDB RESET AND START CHANNEL D 
 0 54200 t aaaaaRSCEB RESET AND START CHANNEL E 
-0 54200 t aaaaaRSCFB RESET AND START CHANNEL F 
 0 54300 t aaaaaRSCGB RESET AND START CHANNEL G 
-0 54300 t aaaaaRSCHB RESET AND START CHANNEL H 
-0 76000 0 00012RTTE REDUNDANCY TAPE TEST 
-0 77200 t aaaaaRUND REWIND AND UNLOAD 
-0 40000 t aaaaaSBMB SUBTRACT MAGNITUDE 
 0 63600 t aaaaaSCAD STORE COMPLEMENT OF INDEX IN ADDRESS 
-0 63600 t aaaaaSCDD STORE COMPLEMENT OF INDEX IN DECREMENT 
 0 64400 t aaaaaSCDAB STORE CHANNEL DIAGNOSTIC,CHANNEL A 
-0 64400 t aaaaaSCDBB STORE CHANNEL DIAGNOSTIC,CHANNEL B 
 0 64500 t aaaaaSCDCB STORE CHANNEL DIAGNOSTIC,CHANNEL C 
-0 64500 t aaaaaSCDDB STORE CHANNEL DIAGNOSTIC,CHANNEL D 
 0 64600 t aaaaaSCDEB STORE CHANNEL DIAGNOSTIC,CHANNEL E 
-0 64600 t aaaaaSCDFB STORE CHANNEL DIAGNOSTIC,CHANNEL F 
 0 64700 t aaaaaSCDGB STORE CHANNEL DIAGNOSTIC,CHANNEL G 
-0 64700 t aaaaaSCDHB STORE CHANNEL DIAGNOSTIC,CHANNEL H 
 0 64000 t aaaaaSCHAB STORE CHANNEL A 
-0 64000 t aaaaaSCHBB STORE CHANNEL B 
 0 64100 t aaaaaSCHCB STORE CHANNEL C 
-0 64100 t aaaaaSCHDB STORE CHANNEL D 
 0 64200 t aaaaaSCHEB STORE CHANNEL E 
-0 64200 t aaaaaSCHFB STORE CHANNEL F 
 0 64300 t aaaaaSCHGB STORE CHANNEL G 
-0 64300 t aaaaaSCHHB STORE CHANNEL H 
 0 77600 t aaaaaSDND SET DENSITY 
 0 05500 t aaaaaSIRG SET INDICATORS OF RIGHT HALF
 0 76000 0 00140SLFE SENSE LIGHTS OFF 
 0 76000 0 00141SLN1E SENSE LIGHTS ON 
 0 76000 0 00142SLN2E SENSE LIGHTS ON 
 0 76000 0 00143SLN3E SENSE LIGHTS ON 
 0 76000 0 00144SLN4E SENSE LIGHTS ON 
-0 76000 0 00140SLTE SENSE LIGHT TEST 
-0 05500 t aaaaaSILG SET INDICATORS OF LEFT HALF
-0 62000 t aaaaaSLQB STORE LEFT HALF MQ 
 0 60200 t aaaaaSLWB STORE LOGICAL WORD 
-0 76000 0 00003SSME SET SIGN MINUS 
 0 76000 0 00003SSPE SET SIGN PLUS 
 0 62100 t aaaaaSTAB STORE ADDRESS 
 0 54400 t aaaaaSTCAB START CHANNEL A 
-0 54400 t aaaaaSTCBB START CHANNEL B 
 0 54500 t aaaaaSTCCB START CHANNEL C 
-0 54500 t aaaaaSTCDB START CHANNEL D 
 0 54600 t aaaaaSTCEB START CHANNEL E 
-0 54600 t aaaaaSTCFB START CHANNEL F 
 0 54700 t aaaaaSTCGB START CHANNEL G 
-0 54700 t aaaaaSTCHB START CHANNEL H 
 0 62200 t aaaaaSTDB STORE DECREMENT 
-0 62500 t aaaaaSTLB STORE INSTRUCTION LOCATION COUNTER 
 0 60400 t aaaaaSTIB STORE INDICATORS
 0 60100 t aaaaaSTOB STORE 
-0 60000 t aaaaaSTQB STORE MQ 
 0 63000 t aaaaaSTPB STORE PREFIX 
-1 ddddd t aaaaaSTRE STORE LOCATION AND TRAP 
 0 62500 t aaaaaSTTB STORE TAG 
 0 60000 t aaaaaSTZB STORE ZERO 
 0 76000 0 00161SWT1E SENSE SWITCH TEST 
 0 76000 0 00162SWT2E SENSE SWITCH TEST 
 0 76000 0 00163SWT3E SENSE SWITCH TEST 
 0 76000 0 00164SWT4E SENSE SWITCH TEST 
 0 76000 0 00165SWT5E SENSE SWITCH TEST 
 0 76000 0 00166SWT6E SENSE SWITCH TEST 
 0 40200 t aaaaaSUBB SUBTRACT 
 0 63400 t aaaaaSXAE STORE INDEX IN ADDRESS 
-0 63400 t aaaaaSXDE STORE INDEX IN DECREMENT 
-0 06000 t aaaaaTCNAB TRANSFER ON CHANNEL A NOT IN OPERATION 
-0 06100 t aaaaaTCNBB TRANSFER ON CHANNEL B NOT IN OPERATION 
-0 06200 t aaaaaTCNCB TRANSFER ON CHANNEL C NOT IN OPERATION 
-0 06300 t aaaaaTCNDB TRANSFER ON CHANNEL D NOT IN OPERATION 
-0 06400 t aaaaaTCNEB TRANSFER ON CHANNEL E NOT IN OPERATION 
-0 06500 t aaaaaTCNFB TRANSFER ON CHANNEL F NOT IN OPERATION 
-0 06600 t aaaaaTCNGB TRANSFER ON CHANNEL G NOT IN OPERATION 
-0 06700 t aaaaaTCNHB TRANSFER ON CHANNEL H NOT IN OPERATION 
 0 06000 t aaaaaTCOAB TRANSFER ON CHANNEL A IN OPERATION 
 0 06100 t aaaaaTCOBB TRANSFER ON CHANNEL B IN OPERATION 
 0 06200 t aaaaaTCOCB TRANSFER ON CHANNEL C IN OPERATION 
 0 06300 t aaaaaTCODB TRANSFER ON CHANNEL D IN OPERATION 
 0 06400 t aaaaaTCOEB TRANSFER ON CHANNEL E IN OPERATION 
 0 06500 t aaaaaTCOFB TRANSFER ON CHANNEL F IN OPERATION 
 0 06600 t aaaaaTCOGB TRANSFER ON CHANNEL G IN OPERATION 
 0 06700 t aaaaaTCOHB TRANSFER ON CHANNEL H IN OPERATION 
 0 03000 t aaaaaTEFAB TRANSFER ON END OF FILE, CHANNEL A 
-0 03000 t aaaaaTEFBB TRANSFER ON END OF FILE, CHANNEL B 
 0 03100 t aaaaaTEFCB TRANSFER ON END OF FILE, CHANNEL C 
-0 03100 t aaaaaTEFDB TRANSFER ON END OF FILE, CHANNEL D 
 0 03200 t aaaaaTEFEB TRANSFER ON END OF FILE, CHANNEL E 
-0 03200 t aaaaaTEFFB TRANSFER ON END OF FILE, CHANNEL F 
 0 03300 t aaaaaTEFGB TRANSFER ON END OF FILE, CHANNEL G 
-0 03300 t aaaaaTEFHB TRANSFER ON END OF FILE, CHANNEL H 
 0 04000 t aaaaaTLQB TRANSFER ON LOW MQ 
 0 04600 t aaaaaTIFB TRANSFER IF INDICATORS OFF
 0 04200 t aaaaaTIOB TRANSFER IF INDICATORS ON
 2 ddddd t aaaaaTIXA TRANSFER ON INDEX 
-0 12000 t aaaaaTMIB TRANSFER ON MINUS 
-0 14000 t aaaaaTNOB TRANSFER ON NO OVERFLOW 
-2 ddddd t aaaaaTNXA TRANSFER ON NO INDEX 
-0 10000 t aaaaaTNZB TRANSFER ON NO ZERO 
 0 01400 t aaaaaTOVB TRANSFER ON OVERFLOW 
 0 12000 t aaaaaTPLB TRANSFER ON PLUS 
 0 16100 t aaaaaTQOB TRANSFER ON MQ OVERFLOW 
 0 16200 t aaaaaTQPB TRANSFER ON MQ PLUS 
 0 02000 t aaaaaTRAB TRANSFER 
 0 02200 t aaaaaTRCAB TRANSFER ON REDUNDANCY CHECK, CHANNEL A 
-0 02200 t aaaaaTRCBB TRANSFER ON REDUNDANCY CHECK, CHANNEL B 
 0 02400 t aaaaaTRCCB TRANSFER ON REDUNDANCY CHECK, CHANNEL C 
-0 02400 t aaaaaTRCDB TRANSFER ON REDUNDANCY CHECK, CHANNEL D 
 0 02600 t aaaaaTRCEB TRANSFER ON REDUNDANCY CHECK, CHANNEL E 
-0 02600 t aaaaaTRCFB TRANSFER ON REDUNDANCY CHECK, CHANNEL F 
 0 02700 t aaaaaTRCGB TRANSFER ON REDUNDANCY CHECK, CHANNEL G 
-0 02700 t aaaaaTRCHB TRANSFER ON REDUNDANCY CHECK, CHANNEL H 
-0 77500 t aaaaaTRSD TEST READY STATUSRPQ
-0 76100 0 00141TSME TEST SIGNIFICANCE MODERPQ
 0 07400 t aaaaaTSXE TRANSFER AND SET INDEX 
 0 02100 t aaaaaTTRB TRAP TRANSFER 
 3 ddddd t aaaaaTXHA TRANSFER ON INDEX HIGH 
 1 ddddd t aaaaaTXIA TRANSFER WITH INDEX INCREMENTED 
-3 ddddd t aaaaaTXLA TRANSFER ON INDEX LOW 
 0 10000 t aaaaaTZEB TRANSFER ON ZERO 
-0 30400 t aaaaaUAMB UNNORMALIZED ADD MAGNITUDE 
-0 30000 t aaaaaUFAB UNNORMALIZED FLOATING ADD 
-0 26000 t aaaaaUFMB UNNORMALIZED FLOATING MULTIPLY 
-0 30200 t aaaaaUFSB UNNORMALIZED FLOATING SUBTRACT 
-0 30600 t aaaaaUSMB UNNORMALIZED FLOATING SUBTRACT MAGNITUDE 
 0 22400 t aaaaaVDHC VARIABLE LENGTH DIVIDE OR HALT  
 0 22500 t aaaaaVDPC VARIABLE LENGTH DIVIDE OR PROCEED 
 0 20400 t aaaaaVLMC VARIABLE LENGTH MULTIPLY 
 0 77000 t aaaaaWEFD WRITE END OF FILE 
 0 76600 t aaaaaWRSD WRITE SELECT 
 0 13100 t aaaaaXCAG EXCHANGE ACCUMULATOR AND MQ 
-0 13000 t aaaaaXCLG EXCHANGE LOGICAL ACCUMULATOR AND MQ 
 0 52200 t aaaaaXECB EXECUTE 
 0 52000 t aaaaaZETB STORAGE ZERO TEST 

For CPY the EA indicated either the location to load the data word or the location to write the data word. Depending on whether the device was in read or write mode. CPY go to next instruction if data copy was successfull. It would skip on instruction on end of file or any error. And it would skip two instructions on end of record. Note all I/O operations destroy the contents of the MQ registers as this was used to assemble data from devices.

For RDS, WRS, etc I/O instructions the EA refered to the device to operate on:

DeviceOctaltoDecimalto
Drums301310193200
Tapes BCD201212129138
Tapes Bin221232145154
Line Printer361 241 
Card Punch341 225 
Card Reader321 209 
CRT Film Printer030 024 

Read or write to drums required that the address to be modified be set with the LDA instruction. Not issuing this would cause the drum to start at address 0. The address was incremented after each copy.