CDC 6000 CPU Instruction Set
| Author | Mark Riordan |
|---|---|
| Original Content | 60bits.net |
This table lists the CPU instructions of a Control Data Corporation 6000 Series computer. It does not list CMU (Compare-and-Move Unit) instructions that briefly appeared on the later Cyber 70 Series. All instructions are either 15 or 30 bits long, and are written in traditional octal.
Instructions which, from my observation, were rarely used are in red. Instructions that were particularly frequently used are in blue.
| Octal | Mnemonic | Description | 6500 Cycles |
|---|---|---|---|
| 00000 | PS | Program Stop | Infinite |
| 01xxkkkkkk | RJ K | Return Jump (call subroutine) | 21 |
| 011jK | RE Bj+K | Read ECS from X0 to A0 for Bj+K words | ? |
| 012jK | WE Bj+K | Write ECS from A0 to X0 for Bj+K words | ? |
| 013jK | XJ Bj+K | Exchange jump (context switch) | ? |
| 02ixkkkkkk | JP Bi+K | Jump | 5/13 |
| 030jkkkkkk | ZR Xj,K | Jump if zero | 5/13 |
| 031jkkkkkk | NZ Xj,K | Jump if non-zero | 5/13 |
| 032jkkkkkk | PL Xj,K | Jump if positive | 5/13 |
| 033jkkkkkk | NG Xj,K | Jump if negative | 5/13 |
| 034jkkkkkk | IR Xj,K | Jump if In Range (not floating point infinity) | 5/13 |
| 035jkkkkkk | OR Xj,K | Jump if Out of Range (floating point infinity) | 5/13 |
| 036jkkkkkk | DF Xj,K | Jump if Definite (good floating point value) | 5/13 |
| 037jkkkkkk | ID Xj,K | Jump if InDefinite (bad floating point value) | 5/13 |
| 04ijkkkkkk | EQ Bi,Bj,K | Jump if Bi=Bj (if i=j, unconditional jump) | 5/13 |
| 05ijkkkkkk | NE Bi,Bj,K | Jump if Bi<>Bj | 5/13 |
| 06ijkkkkkk | GE Bi,Bj,K | Jump if Bi>Bj | 5/13 |
| 07ijkkkkkk | LT Bi,Bj,K | Jump if Bi⇐Bj | 5/13 |
| 10ijx | BXi Xj | Move Xj to Xi | 5 |
| 11ijk | BXi Xj*Xk | Xi:=Xj AND Xk | 5 |
| 12ijk | BXi Xj+Xk | Xi:=Xj OR Xk | 5 |
| 13ijk | BXi Xj-Xk | Xi:=Xj XOR Xk (often used to zero an X reg) | 5 |
| 14ixk | BXi -Xk | Xi:=NOT Xk | 5 |
| 15ijk | BXi -Xj*Xk | Xi:=(NOT Xj) AND Xk | 5 |
| 16ijk | BXi -Xj+Xk | Xi:=(NOT Xj) OR Xk | 5 |
| 17ijk | BXi -Xj-Xk | Xi:=(NOT Xj) XOR Xk | 5 |
| 20ivv | LXi vv | Left shift Xi vv bits circular | 6 |
| 21ivv | AXi vv | Right shift Xi vv bits w/ sign extend | 6 |
| 22ijk | LXi Bj,Xk | Xi:=Xk left shifted circular Bj bits | 6 |
| 23ijk | AXi Bj,Xk | Xi:=Xk right shifted w/ sign extend Bj bits | 6 |
| 24ijk | NXi Bj,Xk | Xi:=Xk normalized; Bj:=# bits Xk was shifted | 6 |
| 25ijk | ZXi Bj,Xk | Xi:=Xk normalized w/ round; Bj:=# bits Xk was shifted | 6 |
| 26ijk | UXi Bj,Xk | Xi:=Mantissa of Xk; Bj:=exponent | 6 |
| 27ijk | PXi Bj,Xk | Xi:=Xk with exponent Bj | 6 |
| 30ijk | FXi Xj+Xk | Xi:=Xj+Xk (floating point) | 11 |
| 31ijk | FXi Xj-Xk | Xi:=Xj-Xk (floating point) | 11 |
| 32ijk | DXi Xj+Xk | Xi:=Xj+Xk (bottom word, double prec.) | 11 |
| 33ijk | DXi Xj-Xk | Xi:=Xj-Xk (bottom word, double prec.) | 11 |
| 34ijk | RXi Xj+Xk | Xi:=Xj+Xk (rounded floating point) | 11 |
| 35ijk | RXi Xj-Xk | Xi:=Xj-Xk (rounded floating point) | 11 |
| 36ijk | IXi Xj+Xk | Xi:=Xj+Xk (60-bit integer) | 6 |
| 37ijk | IXi Xj-Xk | Xi:=Xj-Xk (60-bit integer) | 6 |
| 40ijk | FXi Xj*Xk | Xi:=Xj*Xk (floating point) | 57 |
| 41ijk | RXi Xj*Xk | Xi:=Xj*Xk (rounded floating point) | 57 |
| 42ijk | DXi Xj*Xk | Xi:=Xj*Xk (bottom word, double prec., or 48-bit integer) | 57 |
| 43ivv | MXi vv | Xi:=Mask of vv bits at top of word | 6 |
| 44ijk | FXi Xj/Xk | Xi:=Xj/Xk (floating point) | 57 |
| 45ijk | RXi Xj/Xk | Xi:=Xj/Xk (rounded floating point) | 57 |
| 46000 | NO | No operation | 3 |
| 47ixk | CXi Xk | Xi:=# of bits in Xk (population count) | 68 |
| 50ijkkkkkk | SAi Aj+K | Ai:=Aj+K | 6/12/10 |
| 51ijkkkkkk | SAi Bj+K | Ai:=Bj+K | 6/12/10 |
| 52ijkkkkkk | SAi Xj+K | Ai:=Xj+K | 6/12/10 |
| 53ijk | SAi Xj+Bk | Ai:=Xj+Bk | 6/12/10 |
| 54ijk | SAi Aj+Bk | Ai:=Aj+Bk | 6/12/10 |
| 55ijk | SAi Aj-Bk | Ai:=Aj-Bk | 6/12/10 |
| 56ijk | SAi Bj+Bk | Ai:=Bj+Bk | 6/12/10 |
| 57ijk | SAi Bj-Bk | Ai:=Bj-Bk | 6/12/10 |
| 60ijkkkkkk | SBi Aj+K | Bi:=Aj+K | 5 |
| 61ijkkkkkk | SBi Bj+K | Bi:=Bj+K (SB0 B0+46000 was a common 30-bit noop) | 5 |
| 62ijkkkkkk | SBi Xj+K | Bi:=Xj+K | 5 |
| 63ijk | SBi Xj+Bk | Bi:=Xj+Bk | 5 |
| 64ijk | SBi Aj+Bk | Bi:=Aj+Bk | 5 |
| 65ijk | SBi Aj-Bk | Bi:=Aj-Bk | 5 |
| 66ijk | SBi Bj+Bk | Bi:=Bj+Bk | 5 |
| 67ijk | SBi Bj-Bk | Bi:=Bj-Bk | 5 |
| 70ijkkkkkk | SXi Aj+K | Xi:=Aj+K (18-bit with sign extend) | 6 |
| 71ijkkkkkk | SXi Bj+K | Xi:=Bj+K (18-bit with sign extend) | 6 |
| 72ijkkkkkk | SXi Xj+K | Xi:=Xj+K (18-bit with sign extend) | 6 |
| 73ijk | SXi Xj+Bk | Xi:=Xj+Bk (18-bit with sign extend) | 6 |
| 74ijk | SXi Aj+Bk | Xi:=Aj+Bk (18-bit with sign extend) | 6 |
| 75ijk | SXi Aj-Bk | Xi:=Aj-Bk (18-bit with sign extend) | 6 |
| 76ijk | SXi Bj+Bk | Xi:=Bj+Bk (18-bit with sign extend) | 6 |
| 77ijk | SXi Bj-Bk | Xi:=Bj-Bk (18-bit with sign extend) | 6 |
Lower-case letters are octal digits, as follows:
x = Don't care
i = Register number
j = Register number
k = Register number if single digit, else part of 18-bit constant (usually used as a CPU memory address)
vv = 6-bit constant
Uppercase K = 18-bit CPU memory address
The 6500 Cycles column describes the speed of the instruction on a CDC 6500. Cycle times are minor cycles, with one minor cycle being 100ns.
Cycle times marked as A/B mean the instruction took A cycles if the condition was false, and B if true. Cycle times marked as A/B/C mean the instruction took A cycles if i=0, B cycles if i=1-5, and C cycles if i=6 or 7.
Adapted from Ralph Grishman's Assembly Language Programming for the Control Data 6000 Series and the Cyber 70 Series. (Don't make the mistake, as I sometimes did, of confusing Ralph Grishman with Ralph Griswold, the creator of the SNOBOL and Icon programming languages.)Â Portions from 6000 COMPASS Version 2 Reference Manual, CDC publication number 60279900.