DA10 Twelve- and Eighteen-Bit Computer Interface
The DA10 Twelve- and Eighteen-Bit Computer Interface connects PDP-10 mainframes to a variety of DEC minicomputers which could be equipped with negative I/O buses, for uses such as communication front ends. These included the 12-bit PDP-8, and 18-bit machines such as the PDP-9.
On the PDP-10 side, it connected to the PDP-10 I/O Bus. Thus, it could be connected to KA10 and KI10 CPUs, but only to KL10s with the optional DIA20 In/Out Bus Controller to provide an I/O bus. Unlike the DL10, it didn't use DMA, just programmed I/O. The device's priority level for interrupts is set by a CONO instruction.
The DA10 is used in the DC68A Data Communication System, which uses a PDP-8/I.
PDP-10 standard instructions
The device name ('CCI') stands for 'Computer-Computer Interface'. There are a pair of 36-bit buffer registers, for input and output (from the -10), which may be read and written with DATI and DATO instructions. The slave minicomputers have means to read/write the top and bottom halves of the buffer registers (for 18-bit slaves), and the three 12-bit segments (for the 12-bit machines).
The interface also has two status bits in each direction:
- From -10 full (which we will call 'F10F')
- From -10 empty ('F10E')
- To -10 full ('T10F')
- To -10 empty ('T10E')
An interrupt is triggered in the -10 by the setting of F10E or T10F; similarly, an interrupt in the slave minicomputer is triggered by the setting of F10F or T10E.
CONO CCI
| Unused | Disable self-check | Enable self-check | Clear F10F | Set F10F | Clear F10E | Set F10E | Clear T10F | Set T10F | Clear T10E | Set T10E | Priority interrupt assignment | ||||||
| 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 |
CONI CCI
| Unused | Self-check enabled | Unused | F10F | Unused | F10E | Unused | T10F | Unused | T10E | Priority interrupt assignment | |||||||
| 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 |
External links
- DA-10 PDP-8/9 Interface System Description (DEC-10-IACB-D)
- DA10 PDP-8/9 Interface Instruction Manual (DEC-10-IACA-D)
- DECsystem-10 System Reference Manual (DEC-10-XSRMA-A-D) - documents the DA10 on pp. 5-7—5-12 (pp. 189-194 of the PDF), and the DA10 registers in Appendix C (pg. 357 of the PDF)
