HP Forum Archive 14

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HP75's schematics Message #1 Posted by Claudio on 27 Mar 2004, 1:42 p.m. 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). Thanks. Claudio. (as always delete the two "_nospam_" from e-mail address :-) ) 1234

Re: HP75's schematics Message #2 Posted by Tony Duell on 29 Mar 2004, 12:47 p.m., in response to message #1 by Claudio 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 Message #3 Posted by Claudio on 29 Mar 2004, 3:48 p.m., in response to message #2 by Tony Duell Wow, it seem very interesting! I hope that someone can post it to all the community! Claudio 1234

My name on the list, please... q8^) (N.T.) Message #4 Posted by Vieira, Luiz C. (Brazil) on 29 Mar 2004, 10:26 p.m., in response to message #3 by Claudio ...

Re: My name on the list, please... q8^) (N.T.) Message #5 Posted by Veli-Pekka Nousiainen on 30 Mar 2004, 4:30 p.m., in response to message #4 by Vieira, Luiz C. (Brazil) I own a HP-75C...but what is inside? [VPN]

Re: My name on the list, please... q8^) (N.T.) Message #6 Posted by Eric Smith on 1 Apr 2004, 12:26 a.m., in response to message #5 by Veli-Pekka Nousiainen Quote: 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 Message #7 Posted by Claudio on 1 Apr 2004, 11:35 p.m., in response to message #6 by Eric Smith Really haven't anyone them? :-(( I'm particularly interested to the expansion slots for the RAM and the ROM. Claudio 1234

Re: HP75's schematics Message #8 Posted by Tony Duell on 3 Apr 2004, 12:41 p.m., in response to message #7 by Claudio I have the HP75C service manual, what I don't have is any way to scan it :-(

Re: HP75's schematics Message #9 Posted by Claudio on 3 Apr 2004, 4:44 p.m., in response to message #8 by Tony Duell Arghhhhh #@§!%$#&!# I'm always unlucky!! ;-) Claudio 12345

Re: My name on the list, please... q8^) (N.T.) Message #10 Posted by David Smith on 2 Apr 2004, 12:34 p.m., in response to message #6 by Eric Smith And inside of each of those custom IC's is... magic smoke. Once you let the smoke out of a package it quits working.

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