Chipset for some PDP-11 machines with QBUS.
The chipset consists of a Data Path chip, a Control chip, and two or three microcode ROMs (each containing 512 microwords that are 22 bits wide). (So microcode is more 'vertical' than 'horizontal'.)
A data path chip contains data paths, registers, and logic for executing microinstructions. The control chip contains microinstruction sequencing and control for QBUS.
All uROMs have the same pinout and are wired in parallel, so they can be placed in any of the three uROM positions. The first two uROMs contain the basic PDP-11 instruction set; a third uROM is optional and a number of different options are available.
1,090 / 5,000
There are a number of variants of all the different uROM chips in the base kit; it is not known if all variants are fully interoperable (ie any revision of any chip can be replaced by any other and the machine still works) so combinations will be given.
Circuit numbers of the form 23-xxxxx-rr, etc. are DEC part numbers (where "rr" appears to represent the revision number - 0 if not specified); the corresponding Western Digital numbers are xxxxy etc. (where 'x' is a number and 'y' is a letter) - Western Digital MCP-1600 chipset.
The Data Path circuit is 1611H (different DEC part numbers) and the Control chip is 2007C (similar); all uROM chips are 30xxy.
The following sets (Data, Control, uROM) were observed (first three on LSI-11/2 cards):
3010D contains uROM addresses 0x000-0x1ff and 3007D 23-002B5 contains 0x200-0x3ff.