HP 9845 Microprocessors

Tony Duell ard at p850ug1.demon.co.uk
Fri Jan 18 17:40:08 CST 2008

> I'm trying to nail down a few bits of information regarding the various 
> hybrid microprocessors contained in the earlier versions of the HP 9845. 
> I recently purchased a large lot of 9845 boards, looks like most of one 
> machine plus the PPU from a second machine. All told, I have four hybrid 
> microprocessors. Two are the 107-pin AEC-variant 5061-3001 processor, 
> one on a revision-A PPU card and one on a revision-B PPU card. The other 
> two are both mounted on a single card, which is presumably a 
> pre-bitslice LPU. Of the two processors on this board, one is a 
> 5061-3010, the other a 5061-3011. From what I understand, the -3010 is 
> the original hybrid used in the 9825, and I read something somewhere 
> that lead me to believe the -3011 is a microcode variant of the standard 
> -3010. Are both of these processors part of the LPU? Most sources refer 
> to the 9845 having two processors, the PPU and the LPU, and I haven't 
> found any that say the LPU itself actually consists of two processors. 
> Is the -3011 just a microcode variant of the -3010? Also, are there any 
> microcode variations between the -3001 on a revision-A PPU card and one 
> on a revison-B PPU card?

The first thing to be aware of is that the 9845A and the later 9845s 
(9845B abd 9845C) are _very_ different inside. All have 2 processors, and 
bus aritration logic to access the various ROM and RAM boards. In the 
9845A there is, apparently, one PCB containing the 2 processor hybrid 
modules and a second PCB contianing the bus swithcing. In the 9845B and 
9845C, there are 2 processor boards, each containing one hybrid circuit 
nad half the us switching logic.

I therefore suspect yuor board with 2 hybrids on it is the processor 
board from a 9845A

I've only been inside one 9845. That was a 9845B with the high speed 
language processor. In that machine, the PPU is a hyrid circuit on a PCB 
at the left side of the machione. The LPU is a set of 3 boards (basically 
bus interface, data path, control) with their only little interconnect 
'backplane' at the top. One of the boards has edge fingers on the bottom 
edge, these plug into the main backplane, I believe in place of a single 
PCB containing a hybrid module for the LPU.

There's some information on the 9845B on http://www.hpmuseum.net . 
There's an HP 'boardwapper guide' which might be useful, and some 
unofficial schematics of the 9845B and enhanced mono monitor (be warned 
it's _not_ a simple machine, I think there's a total of over 1000 ICs in 
that configuration)


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