The control memory in a GX515X contains an 8-bit command for each step. These commands are loaded into the on-board sequencer that controls the flow of the program counter and the direction of I/O channels. See the Commands section in “Theory of Operation” of the respective board user guide for information concerning commands and their parameters.
Each location in Control Memory consists of an 8-bit wide ‘Command Word’. the figure below shows the bit fields in each Command Word:
BIT # |
7 |
6 |
5 |
4 |
3 2 |
1 0 |
Command Word |
OE3 |
OE2 |
OE1 |
OE0 |
CND |
Op Code |
GX5150 Command Word
Op Code |
Bit 0 and Bit 1 define the Operation code field. |
CND |
Bit 2 and Bit 3 define the Conditions field. |
OEn |
Bits 4 through bit 7 are the output enables for group n (where n = 0-3). These are valid only when the GX5150 is in output mode. This feature is not used when programmed for input mode. A logic low level enables the corresponding output driver. |
The table below defines bits in the Command Word Op Code field.
Mnemonic |
Code |
Bit 1 |
Bit 0 |
NOP |
0 |
0 |
0 |
JUMP A |
1 |
0 |
1 |
JUMP B |
2 |
1 |
0 |
Pause/HALT |
3 |
1 |
1 |
*Address in the CALL is divided by 8.
The table below defines the bit designations for the condition (CND) field of the Command Word. The conditions define the trigger event that executes the desired jump to a predetermined address location in vector memory.
Mnemonic |
Code |
Bit 1 |
Bit 0 |
None |
0 |
0 |
0 |
Equal |
1 |
0 |
1 |
Not Equal |
2 |
1 |
0 |
Halt |
3 |
1 |
1 |