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HP Forum Archive 15

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Did anyone on this list ever open the HP65 hybrid ?
Message #1 Posted by bernhard on 24 Mar 2006, 6:04 p.m.

Hi folks,

assuming that there are some defective HP65 out there, where the fault location was in the hybrid, did you ever try to open it ? I'd like to find how many chips are inside and how they are interconnected. Maybe somebody on this list could provide a photo (or a series of photos). Sorry for this curiosity - but all of my attempts to buy a truly defunct HP65 on Ebay have failed, all the electronics were good, and I'm reluctant to kill a perfectly functional HP65 main board just to see what's in the hybrid.

Regards, Bernhard

Re: Did anyone on this list ever open the HP65 hybrid ?
Message #2 Posted by Eric Smith on 24 Mar 2006, 7:06 p.m.,
in response to message #1 by bernhard

I haven't opened one, but I've seen an xray of it. IIRC it contains six chips. Based on the HP Journal article, these are most probably:

  • clock driver
  • C&T - control & timing
  • A&R - arithmetic & registers
  • CRC - card reader control
  • program storage circuit (100x6 dynamic shift register)
  • data RAM

Outside the hybrid are six additional chips:

  • three ROM chips
  • card reader analog chip
  • anode and cathode drivers for the display

Tony wrote an article on HP-65 internals which gives pinouts etc.

Half of the ROM source code was listed in two US patents. It may not have been the production release.

The operation of the program storage chip is partially described in the patent, but not in enough detail to write a simulation. A lot of experimentation would be necessary, probably by replacing ROM 0 with a ROM emulator and running custom test programs.

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