Difference between revisions of "KD11-K CPU"
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| 12 || colspan="2" style="text-align:center;" | Unused || colspan="4" style="text-align:center;" | SPC | | 12 || colspan="2" style="text-align:center;" | Unused || colspan="4" style="text-align:center;" | SPC | ||
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| − | | 13 || colspan="2" style="text-align:center;" | Bootstrap || colspan="4" style="text-align:center;" | SPC | + | | 13 || colspan="2" style="text-align:center;" | Memory UNIBUS/Bootstrap || colspan="4" style="text-align:center;" | SPC |
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| − | | 14 || colspan="2" style="text-align:center;" | UNIBUS | + | | 14 || colspan="2" style="text-align:center;" | I/O UNIBUS/Terminator || colspan="4" style="text-align:center;" | SPC |
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Revision as of 01:46, 12 January 2022
The KD11-K was the CPU of the PDP-11/60. It provided the subset PDP-11 memory management, and used a UNIBUS for its main memory access (although a built-in cache was standard).
It provided the full FP11 floating point using microcode; as an option, the FP11-E Floating Point Processor, a 4 hex board co-processor which provided a high-performance implementation, was also available. Also available were either a User Control Store (1KW of read-write microcode), an Extended Control Store (ROM microcode), or a Diagnostic Control Store.
One unusual aspect was that the CPU's backplane had a separate UNIBUS connectors for I/O activity, and for memory access. The FMPS indicates (pg. 4) that devices that do interrupts and DMA must be connected to the I/O UNIBUS, and not to the memory UNIBUS; but it also indicates (pg. 3) that there is only a single UNIBUS. (Perhaps all the bus grant lines from the bus arbitration circuitry in the CPU are only connected to the I/O connector?)
Microcode
It was a microcoded CPU, using 48-bit wide micro-words; the address space of the micro-engine was 212 words, divided into 8 blocks. The allocation of the blocks was:
- Base instructions
- Console and Error log
- EIS, Initialization
- Floating point
- Floating point
- ECS
- ECS/UCS
- ECS/UCS
Implementation
It consisted of a custom 14-slot backplane ((DEC part number 70-12953), and 6 hex boards:
- uWord (M7872)
- Decode (M7873)
- Data Path (M7874)
- KT/Cache (M7875)
- Timing (M7876)
- Status (M7827)
for the basic CPU. They were held in slots 2-7 of the backplane:
| Connector | ||||||
|---|---|---|---|---|---|---|
| Slot | A | B | C | D | E | F |
| 1 | WCS or ECS or DCS (optional) | |||||
| 2 | uWord (M7872) | |||||
| 3 | Decode (M7873) | |||||
| 4 | Data Path (M7874) | |||||
| 5 | KT/Cache (M7875) | |||||
| 6 | Timing (M7876) | |||||
| 7 | Status (M7827) | |||||
| 8 | Floating Point Next Micro-Address (M7878) | |||||
| 9 | Floating Point Exponent (M7879) | |||||
| 10 | Multiplying Network (M7880) | |||||
| 11 | Floating Point ALU (M7881) | |||||
| 12 | Unused | SPC | ||||
| 13 | Memory UNIBUS/Bootstrap | SPC | ||||
| 14 | I/O UNIBUS/Terminator | SPC | ||||
The optional FPP used slots 8-11 of the backplane; a single slot, slot 1, held the microcode option. The remaining slots in the backplane, 12-14, were SPC slots.
External links
- PDP-11/60 - BitSavers
