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HP75's schematics - Printable Version

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HP75's schematics - Claudio - 03-27-2004

Have anyone the HP75's schematics?
Or where can I find them?

I'm examining the possibility to build some expansions (RAM and ROM) for my HP75D. So I need of documentation as much as possible (included the electrical schematics).


(as always delete the two "_nospam_" from e-mail address :-) )


Re: HP75's schematics - Tony Duell - 03-29-2004

There is an HP75C service manual, which includes schematics and bus timing data (for all 'service' meant board-swapping if you were HP). I am pretty sure this manual was available to the public at one point (it was mentioned in PPC journal), so there's probably somebody out there who has both the manual and a scanner.

Re: HP75's schematics - Claudio - 03-29-2004

Wow, it seem very interesting!

I hope that someone can post it to all the community!



My name on the list, please... q8^) (N.T.) - Vieira, Luiz C. (Brazil) - 03-29-2004


Re: My name on the list, please... q8^) (N.T.) - V-PN - 03-30-2004

I own a HP-75C...but what is inside?


Re: My name on the list, please... q8^) (N.T.) - Eric Smith - 04-01-2004

I own a HP-75C...but what is inside?

A bunch of HP custom CMOS chips, including the microprocessor (a CMOS version of the HP-83/85/86/87 "Capricorn" microprocessor), ROMs, display drivers, bus drivers, keyboard controller, clock and alarm, card reader, HP-IL (1LB6 rather than 1LB3), etc. And some industry-standard 2K*8 SRAMs, HM6116 or equivalent.

Re: HP75's schematics - Claudio - 04-01-2004

Really haven't anyone them? :-((

I'm particularly interested to the expansion slots for the RAM and the ROM.



Re: My name on the list, please... q8^) (N.T.) - David Smith - 04-02-2004

And inside of each of those custom IC's is... magic smoke. Once you let the smoke out of a package it quits working.

Re: HP75's schematics - Tony Duell - 04-03-2004

I have the HP75C service manual, what I don't have is any way to scan it :-(

Re: HP75's schematics - Claudio - 04-03-2004

Arghhhhh #@ยง!%$#&!#

I'm always unlucky!! ;-)