The control memory consists of 32 bit commands. Each command is divided into six fields. A command layout diagram with the name of each field and position (bit number) is shown in Table B-1, followed by a definition of each command field in Table B-2.
BIT # |
31 25 |
24 22 |
21 20 |
19 17 |
16 0 |
FIELD NAME |
Reserved (0) |
Operation Code |
Register |
Condition |
Address |
Command Layout
Command Field |
Description |
Reserved, bits 31-25 |
Reserved for future versions. Must be set to 0. |
Operation Code, bits 24-22 |
These bits provide the command code as described in the table Operation Code Field. |
Register, bits 21 and 20 |
Specifies the internal register used with either the related command. |
Condition, bits 19-17 |
This field is the condition code for the related commands and the tree address MSBs for the JUMP FAR command. Condition codes are described in Condition Field table. |
Address, bits 16-0 |
This field contains the address for branch commands: JUMP, LOOP, GOTO and CALL. When the Operations Code is set to the SET command, this field (bits 0-15) is used as data to be assigned to a register. |
Command Field Descriptions
Mnemonic |
Additional fields |
Value |
Bit 24 |
Bit 23 |
Bit 22 |
NOP |
None |
0 |
0 |
0 |
0 |
JUMP FAR |
Address |
1 |
0 |
0 |
1 |
JUMP NEAR |
Address |
2 |
0 |
1 |
0 |
LOOP |
Reg, Address |
3 |
0 |
1 |
1 |
SET |
Reg & Address |
4 |
1 |
0 |
0 |
CALL |
Address* |
5 |
1 |
0 |
1 |
RETURN |
|
6 |
1 |
1 |
0 |
PAUSE |
|
7 |
1 |
1 |
1 |
HALT |
Condition = 7 |
7 |
1 |
1 |
1 |
* Address in the CALL is divided by 8
Condition |
Bit17-19 |
Bit19 |
Bit18 |
Bit17 |
None |
0 |
0 |
0 |
0 |
HALT when combined with PAUSE command |
7 |
1 |
1 |
1 |