Series 16 instructions - Revision history

Jnc: /* Input-output instructions */ Describe I/O opcodes

2025-08-05T13:26:54Z

‎Input-output instructions: Describe I/O opcodes

Jnc: /* Memory reference instructions */ Old, alternate meaning. of 'microcoding'

2025-08-05T09:03:51Z

‎Memory reference instructions: Old, alternate meaning. of 'microcoding'

Jnc: Correct bit names

2025-08-04T23:01:37Z

Correct bit names

Jnc: Details on 'skip' instructions

2025-08-04T21:54:58Z

Details on 'skip' instructions

Jnc: Fairly complete

2025-07-20T21:28:02Z

Fairly complete

New page

'''Series 16 instructions''' are basically the same across all models of the [[Series 16]] line (although some are missing on some models).

Most of the [[instruction]]s are fitted into a basic layout used for the memory reference instructions; specifically, the basic [[opcode]] field is in the same place in all of them (although some instructions 'borrow' bits from other fields).

==Memory reference instructions==
{{16bit-header}}
| Indirect || Index || colspan=4 | Opcode || Sector || colspan=9 | Address
{{16bit-bitout}}

Memory reference instructions can reference i) words in the 'base' sector (normally sector 0), or ii) words in the same sector as that containing the instruction - the choice being controlled by the 'Sector' bit. (An option, "Memory Lockout", is available, which allows the base sector to be relocated; this is utilized in [[time-sharing]] operation.)

The 'Indirect' bit is also called the 'Flag' bit; the 'Index' bit is also called the 'Tag' bit; these become part of the opcode in non-memory-reference instructions. If both are set in an ordinary instruction, indexing takes place before indirection. The indirect address, if used, allows addressing of all locations in memory. The indirect address word also has Flag and Tag bits; normally, there is generally no limit to the number of levels of indirection that can be invoked.

{| class="wikitable" style="text-align: center;"
! Opcode !! Mnemonic !! Action
|-
| 0 || colspan=2 | ''Generic and skip/shift (below)''
|-
| 1 || JMP || Jump
|-
| 2 || LDA || Load A
|-
| 3 || ANA || AND to A
|-
| 4 || STA || Store A
|-
| 5 || ERA || XOR to A
|-
| 6 || ADD || Add
|-
| 7 || SUB || Subtract
|-
| 010 || JST || Jump and Store
|-
| 011 || CAS || Compare
|-
| 012 || IRS || Increment, replace and skip
|-
| 013 || IMA || Interchange memory and A
|-
| 014 || colspan=2 | ''Input-output (below)''
|-
| 015 || LDX/STX || Load X/Store X
|-
| 016 || MPY || Multiply
|-
| 017 || DIV || Divide
|}

==Generic instructions==
{{16bit-header}}
| colspan=16 | Opcode
{{16bit-bitout}}

{| class="wikitable" style="text-align: center;"
! Opcode !! Mnemonic !! Action
|-
| 000000 || HALT || Halt
|-
| 000043 || INK || Input keys
|-
| 000201 || IAB || Interchange A and B
|-
| 000401 || ENB || Enable program interrupt
|-
| 001001 || INH || Inhibit program interrupt
|-
| 140040 || CRA || Clear A
|-
| 140100 || SSP || Set A sign plus
|-
| 140200 || RCB || Reset C bit
|-
| 140401 || CMA || Complement A
|-
| 140500 || SSM || Set A sign minus
|-
| 140600 || SCB || Set C bit
|-
| 141044 || CAR || Clear A, right half
|-
| 141050 || CAL || Clear A, left half
|-
| 141206 || AOA || Add one to A
|-
| 141216 || ACA || Add C to A
|-
| 141340 || ICA || Interchange characters in A
|}

''Not all instructions are listed''

==Skip instructions==
{{16bit-header}}
| colspan=16 | Opcode
{{16bit-bitout}}

{| class="wikitable" style="text-align: center;"
! Opcode !! Mnemonic !! Action
|-
| 100000 || SKP || Unconditional skip
|-
| 100001 || SRC || Skip if C reset
|-
| 100040 || SZE || Skip if A zero
|-
| 100400 || SPL || Skip if A sign plus
|-
| 101000 || NOP || No operation
|-
| 101001 || SSC || Skip if C bit set
|-
| 101040 || SNZ || Skip if A non-zero
|-
| 101400 || SPL || Skip if A sign minus
|}

''Not all instructions are listed''

==Shift instructions==
{{16bit-header}}
| colspan=10 | Opcode || colspan=6 | Count
{{16bit-bitout}}

{| class="wikitable" style="text-align: center;"
! Opcode !! Mnemonic !! Action
|-
| 0400 || LRL || Long right logical
|-
| 0401 || LRS || Long arithmetic right
|-
| 0402 || LRR || Long right rotate
|-
| 0404 || LGR || Logical right
|-
| 0405 || ARS || Arithmetic right
|-
| 0406 || ARR || Logical right rotate
|-
| 0410 || LLL || Long left logical
|-
| 0411 || LLS || Long arithmetic left
|-
| 0412 || LLR || Long left rotate
|-
| 0414 || LGL || Logical left
|-
| 0415 || ALS || Arithmetic left
|-
| 0416 || ALR || Logical left rotate
|}

The shift count is given in [[two's complement]] form.

==Input-output instructions==
{{16bit-header}}
| colspan=6 | Opcode || colspan=4 | Function || colspan=6 | Device
{{16bit-bitout}}

{| class="wikitable" style="text-align: center;"
! FT !! Mnemonic !! Action
|-
| 00 || OCP || Output control pulse
|-
| 01 || SKS || Skip if ready set
|-
| 10 || INA || Input to A
|-
| 11 || OTA || Output from A
|}

{{semi-stub}}

==External links==

* [http://www.bitsavers.org/pdf/computerControlCompany/ ComputerControlCompany] - documentation at [[Bitsavers]] (extensive)
* [http://www.bitsavers.org/pdf/computerControlCompany/ddp-116/ ddp-116]
* [https://simh.trailing-edge.com/docs/decodingh316.pdf Decoding The H316/H516 “Generic A” Instructions]

[[Category: Minicomputers]]
[[Category: 16-bit Computers]]

@@ Line 203: / Line 203: @@
 ! Opcode !! II/FT !! Mnemonic !! Action
 |-
-| 140 || 00 || OCP || Output control pulse
+| 030 || 00 || OCP || Output control pulse
 |-
-| 340 || 01 || SKS || Skip if ready set
+| 070 || 01 || SKS || Skip if ready set
 |-
-| 540 || 10 || INA || Input to A
+| 130 || 10 || INA || Input to A
 |-
-| 740 || 11 || OTA || Output from A
+| 170 || 11 || OTA || Output from A
 |}
 {{semi-stub}}

@@ Line 62: / Line 62: @@
 |}
-'Generic A' and skip instructions use [[microcode#Another meaning|'microcoding']] (see below).
+'Generic A' and skip instructions use 'microcoding' (in the old, [[microcode#Another meaning|alternate meaning]], of that term) (see below).
 ==Generic instructions==

@@ Line 48: / Line 48: @@
 |}
-For opcode '0', the Indirect/Flag bits determine the type of the instruction:
+For opcode '0', the Indirect/Index bits determine the type of the instruction:
 {| class="wikitable" style="text-align: center;"
-! IF/FT !! Action
+! II/FT !! Action
 |-
 | 0 || Type B Generic instructions
@@ Line 201: / Line 201: @@
 {| class="wikitable" style="text-align: center;"
-! Opcode !! IF/FT !! Mnemonic !! Action
+! Opcode !! II/FT !! Mnemonic !! Action
 |-
 | 140 || 00 || OCP || Output control pulse

@@ Line 39: / Line 39: @@
 | 013 || IMA || Interchange memory and A
 |-
-| 014 || colspan=2 | ''Input-output (below)''
+| 014 || colspan=2 | ''[[#Input-output instructions|Input-output]]''
 |-
 | 015 || LDX/STX || Load X/Store X
@@ Line 47: / Line 47: @@
 | 017 || DIV || Divide
 |}
 ==Generic instructions==
 {{16bit-header}}
 | colspan=16 | Opcode
-{{16bit-bitout}}
+{{16bitoctal-bitout}}
 {| class="wikitable" style="text-align: center;"
@@ Line 65: / Line 83: @@
 |-
 | 001001 || INH || Inhibit program interrupt
 |-
 | 140040 || CRA || Clear A
@@ Line 93: / Line 117: @@
 ==Skip instructions==
 {{16bit-header}}
-| colspan=16 | Opcode
+| colspan=6 | 100 || R || P || M || E || Z || colspan=4 | Sense switches || C
-{{16bit-bitout}}
+{{16bitoctal-bitout}}
 {| class="wikitable" style="text-align: center;"
@@ Line 121: / Line 163: @@
 {{16bit-header}}
 | colspan=10 | Opcode || colspan=6 | Count
-{{16bit-bitout}}
+{{16bitoctal-bitout}}
 {| class="wikitable" style="text-align: center;"
@@ Line 156: / Line 198: @@
 {{16bit-header}}
 | colspan=6 | Opcode || colspan=4 | Function || colspan=6 | Device
-{{16bit-bitout}}
+{{16bitoctal-bitout}}
 {| class="wikitable" style="text-align: center;"
-! FT !! Mnemonic !! Action
+! Opcode !! IF/FT !! Mnemonic !! Action
 |-
-| 00 || OCP || Output control pulse
+| 140 || 00 || OCP || Output control pulse
 |-
-| 01 || SKS || Skip if ready set
+| 340 || 01 || SKS || Skip if ready set
 |-
-| 10 || INA || Input to A
+| 540 || 10 || INA || Input to A
 |-
-| 11 || OTA || Output from A
+| 740 || 11 || OTA || Output from A
 |}
@@ Line 176: / Line 218: @@
 * [http://www.bitsavers.org/pdf/computerControlCompany/ ComputerControlCompany] - documentation at [[Bitsavers]] (extensive)
 * [http://www.bitsavers.org/pdf/computerControlCompany/ddp-116/ ddp-116]
 * [https://simh.trailing-edge.com/docs/decodingh316.pdf Decoding The H316/H516 “Generic A” Instructions]
 [[Category: Minicomputers]]
 [[Category: 16-bit Computers]]