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 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.
|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|
|Unused||Self-check enabled||Unused||F10F||Unused||F10E||Unused||T10F||Unused||T10E||Priority interrupt assignment|