At 02:35 AM 5/3/06 +0100, you wrote:
A rather strange question : Was there ever an 68020
daughterboard for
the HP9817 (aka HP9000/217)?
Not that i've ever heard of. It's definity not mentioned in any of the
HP catalogs, installation guides or configuration guides. AFIK The 9000 200
series were strickly 68000 and 68010 based but it's POSSIBLE that the
circuit card used in the 9817 were designed to also be used in some of the
68020 based 9000 300 series machines. FWIW I've only seen one of two 9817s
and I don't think I've ever powered one up or taken one apart.
The reason I ask is as follows. The HP9817 (I have one in bits on the bench
at the moment) uses a 68010 processor. It's in a PGA pacakge, and is
socketed. As the data sheet shows, it's a 10*10 PGA, with 2 rows of pins
round the outside, and the 4 internal corner pins (a total of 68 pins).
However the socket on the HP9817 board has all 100 contacts fitted. And
some of the ones that don't correspond to pins on the 68010 have traces
going to them. It appears these are extra intputs to the MMU circuit (in
particular to the 'Tag RAM' for virtual memory paging).
Sounds like that socket may be intended for a daughterboard with
additional memory.
Joe
I am wondering, therefore, if the machine was designed to take a
processor with more address lines brought out, the obvious candidate
being the 68020. Of corse it would need a daughterboard to rearrange the
pinout, but apart from that it may well drop straight in.
-tony