Editing IBM 1401 (section)

==Character and op codes==
{{SpecialChars}}

The 1401's operation codes are single characters. In many cases, particularly for the more common instructions, the character chosen is [[mnemonic]] for the operation: A for add, B for branch, S for subtract, etc.

{{hidden begin
|title = Table of character and op codes
|titlestyle = background:#ccccff;
}}

The table is in Character [[Collation|Collating]] Sequence.

: Note: If Word mark bit is set, then the ''C'' bit will be opposite of shown. The ''C'' bit is determined and checked automatically by the machine - normally it is of no concern to the programmers. The only way the ''C'' bit can be entered is by manually using the switches on the Auxiliary Console.  <!-- deleted "for CE" use, see LRM p.116-->A programmer might use these switches to make quick patches while debugging.

{| class="wikitable"
|-
! [[Binary-coded decimal#IBM and BCD|BCD]] Character
! Print-A
! Print-H
! &nbsp;Card&nbsp;
! BCD
w/o M
! Operation
! ''Definition'' & Notes
|-
| align="center" | Blank
| align="center" | &nbsp;
| align="center" | &nbsp;
| &nbsp;
| <code>C&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code>
| &nbsp;
| &nbsp;
|-
| align="center" | .
| align="center" | .
| align="center" | .
| 12-3-8
| <code>&nbsp;BA8&nbsp;21</code>
| Halt
| &nbsp;
|-
| align="center" | ⌑
| align="center" | ⌑
| align="center" | )
| 12-4-8
| <code>CBA84&nbsp;&nbsp;</code>
| Clear Word Mark
| ''Lozenge''
|-
| align="center" | <nowiki>[</nowiki>
| align="center" | &nbsp;
| align="center" | &nbsp;
| 12-5-8
| <code>&nbsp;BA84&nbsp;1</code>
| &nbsp;
| &nbsp;
|-
| align="center" | <
| align="center" | &nbsp;
| align="center" | &nbsp;
| 12-6-8
| <code>&nbsp;BA842&nbsp;</code>
| &nbsp;
| ''Less Than''
|-
| align="center" | [[File:IBM 1401 Group Mark.GIF]]
| align="center" | &nbsp;
| align="center" | &nbsp;
| 12-7-8
| <code>CBA8421</code>
| &nbsp;
| ''Group Mark''
|-
| align="center" | &
| align="center" | &
| align="center" | +
| 12
| <code>CBA&nbsp;&nbsp;&nbsp;&nbsp;</code>
| &nbsp;
| &nbsp;
|-
| align="center" | $
| align="center" | $
| align="center" | $
| 11-3-8
| <code>CB&nbsp;8&nbsp;21</code>
| &nbsp;
| &nbsp;
|-
| align="center" | *
| align="center" | *
| align="center" | *
| 11-4-8
| <code>&nbsp;B&nbsp;84&nbsp;&nbsp;</code>
| &nbsp;
| &nbsp;
|-
| align="center" | <nowiki>]</nowiki>
| align="center" | &nbsp;
| align="center" | &nbsp;
| 11-5-8
| <code>CB&nbsp;84&nbsp;1</code>
| &nbsp;
| &nbsp;
|-
| align="center" | ;
| align="center" | &nbsp;
| align="center" | &nbsp;
| 11-6-8
| <code>CB&nbsp;842&nbsp;</code>
| &nbsp;
| &nbsp;
|-
| align="center" | Δ
| align="center" | &nbsp;
| align="center" | &nbsp;
| 11-7-8
| <code>&nbsp;B&nbsp;8421</code>
| &nbsp;
| ''Delta'' (Mode Change)
|-
| align="center" | -
| align="center" | -
| align="center" | -
| 11
| <code>&nbsp;B&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code>
| &nbsp;
| &nbsp;
|-
| align="center" | /
| align="center" | /
| align="center" | /
| 0-1
| <code>C&nbsp;A&nbsp;&nbsp;&nbsp;1</code>
| Clear Storage
| &nbsp;
|-
| align="center" |,
| align="center" |,
| align="center" |,
| 0-3-8
| <code>C&nbsp;A8&nbsp;21</code>
| Set Word Mark
| &nbsp;
|-
| align="center" | %
| align="center" | %
| align="center" | (
| 0-4-8
| <code>&nbsp;&nbsp;A84&nbsp;&nbsp;</code>
| Divide
| Optional special feature.
|-
| align="center" | ˠ
| align="center" | &nbsp;
| align="center" | &nbsp;
| 0-5-8
| <code>C&nbsp;A84&nbsp;1</code>
| &nbsp;
| ''Word Separator''
|-
| align="center" | \
| align="center" | &nbsp;
| align="center" | &nbsp;
| 0-6-8
| <code>C&nbsp;A842&nbsp;</code>
| &nbsp;
| ''Left Oblique''
|-
| align="center" | ⧻
| align="center" | &nbsp;
| align="center" | &nbsp;
| 0-7-8
| <code>&nbsp;&nbsp;A8421</code>
| &nbsp;
| ''Tape Segment Mark''
|-
| align="center" | ƀ
| align="center" | ‡
| align="center" | ‡
| bgcolor="C0C0C0" | N/A
0
&nbsp;
| <code>&nbsp;&nbsp;A&nbsp;&nbsp;&nbsp;&nbsp;</code>
| &nbsp;
| Cannot be read from card without a no-cost [[Request price quotation|RPQ]], in which case it is read as 8–2.{{efn|The RPQ "Reader/Punch Card Code 8-2 and A-Bit Compatibility" (898148) causes the 1401 to read/punch the A bit as 8-2 for compatibility with the IBM 1410.<ref>{{cite web|title=Custom Features for IBM 1401, 1440, and 1460 Data Processing Systems |url=http://bitsavers.org/pdf/ibm/140x/A24-3315-0_1401customFeatur.pdf |access-date=September 23, 2015 |url-status=dead |archive-url=https://web.archive.org/web/20120829025513/http://www.bitsavers.org/pdf/ibm/140x/A24-3315-0_1401customFeatur.pdf |archive-date=August 29, 2012 |df=mdy-all }}</ref>}}
Punches as zero (or 8–2 with the RPQ).
''Blank with "even-parity"'' on tape.
|-
| align="center" | #
| align="center" | #
| align="center" | =
| 3-8
| <code>&nbsp;&nbsp;&nbsp;8&nbsp;21</code>
| Modify Address
| Optional (requires more than
4000 characters of memory)
|-
| align="center" | @
| align="center" | @
| align="center" | '
| 4-8
| <code>C&nbsp;&nbsp;84&nbsp;&nbsp;</code>
| Multiply
| Optional special feature.
|-
| align="center" | :
| align="center" | &nbsp;
| align="center" | &nbsp;
| 5-8
| <code>&nbsp;&nbsp;&nbsp;84&nbsp;1</code>
| &nbsp;
| &nbsp;
|-
| align="center" | >
| align="center" | &nbsp;
| align="center" | &nbsp;
| 6-8
| <code>&nbsp;&nbsp;&nbsp;842&nbsp;</code>
| &nbsp;
| ''Greater Than''
|-
| align="center" | √
| align="center" | &nbsp;
| align="center" | &nbsp;
| 7-8
| <code>C&nbsp;&nbsp;8421</code>
| &nbsp;
| ''Tape Mark''
|-
| align="center" | ?
| align="center" | &
| align="center" | &
| 12-0
| <code>CBA8&nbsp;2&nbsp;</code>
| Zero and Add
| ''Plus Zero''
|-
| align="center" | A
| align="center" | A
| align="center" | A
| 12-1
| <code>&nbsp;BA&nbsp;&nbsp;&nbsp;1</code>
| Add
| &nbsp;
|-
| align="center" | B
| align="center" | B
| align="center" | B
| 12-2
| <code>&nbsp;BA&nbsp;&nbsp;2&nbsp;</code>
| Branch or Branch on Indicator 
| See [[IBM 1401#Modifiers for five-character Branch On Indicator (B) instruction|"Modifiers for five-character Branch on Indicator (B) instruction"]] section
|-
| align="center" | C
| align="center" | C
| align="center" | C
| 12-3
| <code>CBA&nbsp;&nbsp;21</code>
| Compare
| &nbsp;
|-
| align="center" | D
| align="center" | D
| align="center" | D
| 12-4
| <code>&nbsp;BA&nbsp;4&nbsp;&nbsp;</code>
| Move Numerical
| (Bits)
|-
| align="center" | E
| align="center" | E
| align="center" | E
| 12-5
| <code>CBA&nbsp;4&nbsp;1</code>
| Move Characters and Edit
| &nbsp;
|-
| align="center" | F
| align="center" | F
| align="center" | F
| 12-6
| <code>CBA&nbsp;42&nbsp;</code>
| Control Carriage
| (Printer)
|-
| align="center" | G
| align="center" | G
| align="center" | G
| 12-7
| <code>&nbsp;BA&nbsp;421</code>
| &nbsp;
| &nbsp;
|-
| align="center" | H
| align="center" | H
| align="center" | H
| 12-8
| <code>&nbsp;BA8&nbsp;&nbsp;&nbsp;</code>
| Store B-Address Register
| Optional special feature.
|-
| align="center" | I
| align="center" | I
| align="center" | I
| 12-9
| <code>CBA8&nbsp;&nbsp;1</code>
| &nbsp;
| &nbsp;
|-
| align="center" | !
| align="center" | -
| align="center" | -
| 11-0
| <code>&nbsp;B&nbsp;8&nbsp;2&nbsp;</code>
| Zero and Subtract
| ''Minus Zero''
|-
| align="center" | J
| align="center" | J
| align="center" | J
| 11-1
| <code>CB&nbsp;&nbsp;&nbsp;&nbsp;1</code>
| &nbsp;
| &nbsp;
|-
| align="center" | K
| align="center" | K
| align="center" | K
| 11-2
| <code>CB&nbsp;&nbsp;&nbsp;2&nbsp;</code>
| Select Stacker and other device controls
| See [[IBM 1401#Modifiers for Select Stacker (K) instruction|"Modifiers for Select Stacker (K) instruction"]] section
|-
| align="center" | L
| align="center" | L
| align="center" | L
| 11-3
| <code>&nbsp;B&nbsp;&nbsp;&nbsp;21</code>
| Load Characters to Word Mark
| &nbsp;
|-
| align="center" | M
| align="center" | M
| align="center" | M
| 11-4
| <code>CB&nbsp;&nbsp;4&nbsp;&nbsp;</code>
| Move Characters to Word Mark
| &nbsp;
|-
| align="center" | N
| align="center" | N
| align="center" | N
| 11-5
| <code>&nbsp;B&nbsp;&nbsp;4&nbsp;1</code>
| No Operation
| &nbsp;
|-
| align="center" | O
| align="center" | O
| align="center" | O
| 11-6
| <code>&nbsp;B&nbsp;&nbsp;42&nbsp;</code>
| &nbsp;
| &nbsp;
|-
| align="center" | P
| align="center" | P
| align="center" | P
| 11-7
| <code>CB&nbsp;&nbsp;421</code>
| Move Characters to
Record or Group Mark
| Optional special feature.
|-
| align="center" | Q
| align="center" | Q
| align="center" | Q
| 11-8
| <code>CB&nbsp;8&nbsp;&nbsp;&nbsp;</code>
| Store A-Address Register
| Optional special feature.
|-
| align="center" | R
| align="center" | R
| align="center" | R
| 11-9
| <code>&nbsp;B&nbsp;8&nbsp;&nbsp;1</code>
| &nbsp;
| &nbsp;
|-
| align="center" | ‡
| align="center" | ‡
| align="center" | ‡
| 0-2-8
| <code>&nbsp;&nbsp;A8&nbsp;2&nbsp;</code>
| &nbsp;
| ''Record Mark''
|-
| align="center" | S
| align="center" | S
| align="center" | S
| 0-2
| <code>C&nbsp;A&nbsp;&nbsp;2&nbsp;</code>
| Subtract
| &nbsp;
|-
| align="center" | T
| align="center" | T
| align="center" | T
| 0-3
| <code>&nbsp;&nbsp;A&nbsp;&nbsp;21</code>
| Translate
| (1460 only)
|-
| align="center" | U
| align="center" | U
| align="center" | U
| 0-4
| <code>C&nbsp;A&nbsp;4&nbsp;&nbsp;</code>
| Control Unit
| (Tape)
|-
| align="center" | V
| align="center" | V
| align="center" | V
| 0-5
| <code>&nbsp;&nbsp;A&nbsp;4&nbsp;1</code>
| Branch if Word Mark
and/or Zone
| &nbsp;
|-
| align="center" | W
| align="center" | W
| align="center" | W
| 0-6
| <code>&nbsp;&nbsp;A&nbsp;42&nbsp;</code>
| Branch if Bit Equal
| Optional special feature.
|-
| align="center" | X
| align="center" | X
| align="center" | X
| 0-7
| <code>C&nbsp;A&nbsp;421</code>
| Move and Insert Zeros
| Optional special feature.
|-
| align="center" | Y
| align="center" | Y
| align="center" | Y
| 0-8
| <code>C&nbsp;A8&nbsp;&nbsp;&nbsp;</code>
| Move Zone
| (Bits)
|-
| align="center" | Z
| align="center" | Z
| align="center" | Z
| 0-9
| <code>&nbsp;&nbsp;A8&nbsp;&nbsp;1</code>
| Move Characters and
Suppress Zeros
| &nbsp;
|-
| align="center" | 0
| align="center" | 0
| align="center" | 0
| 0
| <code>C&nbsp;&nbsp;8&nbsp;2&nbsp;</code>
| &nbsp;
| &nbsp;
|-
| align="center" | 1
| align="center" | 1
| align="center" | 1
| 1
| <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1</code>
| Read a Card
| &nbsp;
|-
| align="center" | 2
| align="center" | 2
| align="center" | 2
| 2
| <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;</code>
| Write a Line
| &nbsp;
|-
| align="center" | 3
| align="center" | 3
| align="center" | 3
| 3
| <code>C&nbsp;&nbsp;&nbsp;&nbsp;21</code>
| Write and Read
| &nbsp;
|-
| align="center" | 4
| align="center" | 4
| align="center" | 4
| 4
| <code>&nbsp;&nbsp;&nbsp;&nbsp;4&nbsp;&nbsp;</code>
| Punch a Card
| &nbsp;
|-
| align="center" | 5
| align="center" | 5
| align="center" | 5
| 5
| <code>C&nbsp;&nbsp;&nbsp;4&nbsp;1</code>
| Read and Punch
| &nbsp;
|-
| align="center" | 6
| align="center" | 6
| align="center" | 6
| 6
| <code>C&nbsp;&nbsp;&nbsp;42&nbsp;</code>
| Write and Punch
| &nbsp;
|-
| align="center" | 7
| align="center" | 7
| align="center" | 7
| 7
| <code>&nbsp;&nbsp;&nbsp;&nbsp;421</code>
| Write, Read, and Punch
| &nbsp;
|-
| align="center" | 8
| align="center" | 8
| align="center" | 8
| 8
| <code>&nbsp;&nbsp;&nbsp;8&nbsp;&nbsp;&nbsp;</code>
| Start Read Feed
| Optional special feature.
|-
| align="center" | 9
| align="center" | 9
| align="center" | 9
| 9
| <code>C&nbsp;&nbsp;8&nbsp;&nbsp;1</code>
| Start Punch Feed
| Optional special feature.
|-
|}

Two of the instructions, Branch on Indicator (B) and Select Stacker (K), use a "modifier" operand.

{{Col-begin}}
{{Col-break}}
 
===Modifiers for five-character Branch on Indicator (B) instruction===
The B opcode, if followed by a three-character operand, was a simple unconditional branch to the indicated address. If a fourth operand character was  present (making five characters total including the opcode), this made it a conditional branch. This "modifier" character specified the condition to be tested.

{| class="wikitable"
|-
! [[Binary-coded decimal#IBM and BCD|BCD]] Character
! Unit
! Meaning
|-
| align="center" | Blank
| 1401
| Unconditional—no word mark needed in next character
|-
| align="center" | 1
| 1009
| in run condition
|-
| &nbsp;
| 1011
| punch in backspace operation
|-
| &nbsp;
| 1011
| reader parity indicator on
|-
| &nbsp;
| 1231
| auto select
|-
| &nbsp;
| 1285
| error
|-
| &nbsp;
| 1412
| control-check indicator on
|-
| &nbsp;
| 1418
| late read
|-
| &nbsp;
| 1419
| document to be read
|-
| &nbsp;
| 1428
| late read or late reading mode change
|-
| &nbsp;
| 1445
| printer error
|-
| &nbsp;
| 7340
| hypertape unusual end
|-
| &nbsp;
| 7740
| transmission complete with abnormal status
|-
| &nbsp;
| DDC
| transmission error
|-
| align="center" | 2
| 1009
| buffer available
|-
| &nbsp;
| 1011
| punch ready
|-
| &nbsp;
| 1011
| reader ready
|-
| &nbsp;
| 1231
| full buffer
|-
| &nbsp;
| 1285
| end of line
|-
| &nbsp;
| 1412
| reader-not-ready signal on
|-
| &nbsp;
| 1418
| ready to engage
|-
| &nbsp;
| 1419
| document under read head (PDS 4)
|-
| &nbsp;
| 1428
| ready to engage
|-
| &nbsp;
| 7340
| hypertape normal end
|-
| &nbsp;
| 7740
| transmission complete successfully
|-
| &nbsp;
| DDC
| transmission ended by GMWM
|-
| align="center" | 3
| 1009
| good transmission occurred
|-
| &nbsp;
| 1011
| punch not ready to receive data
|-
| &nbsp;
| 1231
| ready to read
|-
| &nbsp;
| 1285
| reader transporting
|-
| &nbsp;
| 1412
| read-check indicator on
|-
| &nbsp;
| 1418
| document under selected read station
|-
| &nbsp;
| 1419
| valid amount field
|-
| &nbsp;
| 1428
| document under selected read station
|-
| &nbsp;
| 7340
| hypertape control unit 7641 busy
|-
| &nbsp;
| 7740
| receive request
|-
| &nbsp;
| DDC
| read request
|-
| align="center" | 4
| 1009
| reply-bad indicator on
|-
| &nbsp;
| 1011
| punch not ready to read
|-
| &nbsp;
| 1231
| empty hopper
|-
| &nbsp;
| 1285
| marked line
|-
| &nbsp;
| 1412
| amount-field indicator on
|-
| &nbsp;
| 1419
| valid process-control field
|-
| &nbsp;
| 7340
| hypertape attention
|-
| &nbsp;
| 7740
| 7740 attention
|-
| &nbsp;
| DDC
| write request
|-
| align="center" | 5
| 1009
| error reply acknowledgement
|-
| &nbsp;
| 1011
| punch overextended
|-
| &nbsp;
| 1231
| read error or overrun
|-
| &nbsp;
| 1285
| header information
|-
| &nbsp;
| 1412
| process-control indicator on
|-
| &nbsp;
| 1418
| document end
|-
| &nbsp;
| 1419
| valid account-number field
|-
| &nbsp;
| 1428
| document end
|-
| &nbsp;
| 1445
| printer busy
|-
| align="center" | 6
| 1009
| program attention required
|-
| &nbsp;
| 1011
| punch supply reel low or chad box full
|-
| &nbsp;
| 1231
| timing mark check
|-
| &nbsp;
| 1285
| ready to read a line
|-
| &nbsp;
| 1412
| account-number indicator on
|-
| &nbsp;
| 1418
| character on line
|-
| &nbsp;
| 1419
| valid transit-number field
|-
| &nbsp;
| 1428
| character on line
|-
| &nbsp;
| 1445
| carriage busy
|-
| &nbsp;
| DDC
| write in progress
|-
| align="center" | 7
| 1009
| end of message
|-
| &nbsp;
| 1285
| reader ready
|-
| &nbsp;
| 1412
| transit-number indicator on
|-
| &nbsp;
| 1418
| empty hopper and transport (end of file)
|-
| &nbsp;
| 1419
| valid serial-number field
|-
| &nbsp;
| 1428
| empty hopper and transport (end of file)
|-
| &nbsp;
| 1445
| carriage channel 9
|-
| &nbsp;
| DDC
| read in progress
|-
| align="center" | 8
| 1009
| end of file
|-
| &nbsp;
| 1285
| end of file
|-
| &nbsp;
| 1412
| document-spacing-check indicator on
|-
| &nbsp;
| 1418
| ready to read
|-
| &nbsp;
| 1419
| auto-select
|-
| &nbsp;
| 1428
| ready to read
|-
| &nbsp;
| 1448
| carriage channel 12
|-
| &nbsp;
| DDC
| system A stopped
|-
| align="center" | 9
| 1403
| carriage tape channel 9
|-
| align="center" | 0
| 1404
| validity error
|-
| align="center" | ' or @
| 1403
| carriage tape channel 12
|-
| align="center" | >
| 1448
| end of block
|-
| align="center" | /
| 1401
| unequal compare
|-
| align="center" | S
| 1401
| equal compare
|-
| align="center" | T
| 1401
| low compare
|-
| align="center" | U
| 1401
| high compare
|-
| align="center" | V
| 1301
| disk error
|-
| &nbsp;
| 1311
| disk error
|-
| &nbsp;
| 1405
| read or write parity check or read back check error
|-
| align="center" | W
| 1301
| wrong-length record
|-
| &nbsp;
| 1311
| wrong-length record
|-
| &nbsp;
| 1405
| wrong-length record
|-
| align="center" | X
| 1301
| unequal address compare
|-
| &nbsp;
| 1311
| unequal address compare
|-
| &nbsp;
| 1405
| unequal address compare
|-
| align="center" | Y
| 1301
| any disk-unit error condition
|-
| &nbsp;
| 1311
| any disk-unit error condition
|-
| &nbsp;
| 1405
| any disk-unit error condition
|-
| align="center" | Z
| 1401
| arithmetic overflow
|-
| align="center" | ‡
| 1403
| printer error (record mark)
|-
| align="center" | ( or %
| 1401
| process check with process check switch off
|-
| &nbsp;
| 1440
| I/O check stop switch off
|-
| align="center" | \
| 1301
| access busy
|-
| &nbsp;
| 1311
| access busy
|-
| align="center" | J
| 1419
| I/O channel-busy indicator
|-
| &nbsp;
| TAU
| tape busy
|-
| &nbsp;
| SIO
| serial input-output busy
|-
| align="center" | K
| TAU
| end of reel (writing) or tape mark (reading)
|-
| align="center" | L
| TAU
| tape error
|-
| align="center" | N
| 1301
| access inoperable
|-
| &nbsp;
| 1311
| access inoperable
|-
| &nbsp;
| 1405
| access inoperable
|-
| align="center" | P
| 1403
| printer busy
|-
| align="center" | Q
| 1407
| inquiry request
|-
| align="center" | R
| 1403
| carriage busy
|-
| align="center" | !
| 1402
| punch error
|-
| align="center" | *
| 1407
| inquiry clear
|-
| align="center" | + or &
| 1442
| last card (Reader unit 2)
|-
| align="center" | A
| 1402
| last card if SS A is on
|-
| align="center" | B
| 1401
| SS B
|-
| &nbsp;
| 7340
| hypertape attention response
|-
| align="center" | C
| 1401
| SS C
|-
| align="center" | D
| 1401
| SS D
|-
| align="center" | E
| 1401
| SS E
|-
| &nbsp;
| 7340
| hypertape end response
|-
| align="center" | F
| 1401
| SS F
|-
| align="center" | G
| 1401
| SS G
|-
| align="center" | H
| 1402
| reader busy
|-
| align="center" | I
| 1402
| punch busy
|-
| align="center" | ?
| 1402
| reader error
|-
| align="center" | <
| 1448
| early warning
|-
|}

{{Col-break}}

===Modifiers for Select Stacker (K) instruction===
The Select Stacker (K) instruction sent commands to various devices. It was named for its relevance to the 1402 reader/punch.

{| class="wikitable"
|-
! [[Binary-coded decimal#IBM and BCD|BCD]] Character
! Unit
! Meaning
|-
| align="center" | Blank
| 1401
| set program activity recording at BBB only if A is, dd
|-
| align="center" | 1
| 1402
| select last card read to stacker 1 if within 10 ms
|-
| align="center" | 2
| 1402
| select last card read to stacker 8/2 if within 10 ms
|-
| align="center" | 4
| 1402
| select previous card punched to stacker 4
|-
| align="center" | 8
| 1402
| select previous card punched to stacker 8/2
|-
| align="center" | = or #
| 1444
| select previous card punched to stacker 2
|-
| align="center" | L
| 1009
| operate in load mode
|-
| align="center" | $
| 1402
| overlap on
|-
| align="center" | A
| 1009
| suppress 3-second alarm
|-
| align="center" | C
| DDC
| read request
|-
| align="center" | D
| 1009
| set direction to receive
|-
| &nbsp;
| DDC
| write request
|-
| align="center" | E
| 1009
| set direction to transmit
|-
| &nbsp;
| DDC
| reset
|-
| align="center" | F
| 1009
| send EOF
|-
| align="center" | .
| 1402
| overlap off
|-
| align="center" | )
| 1402
| reset overlap
|-
|}
{{col-end}}

{{hidden end}}