From spetrov@purdue.edu Mon Nov 13 10:54:13 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!purdue!spetrov
From: spetrov@purdue.edu (Seo-yeon Petrov)
Newsgroups: comp.sys.m68k
Subject: Question: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1995Nov13.105413.6066@purdue.edu>
Date: Mon, 13 Nov 1995 10:54:13 GMT
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Managed to dump the 27256 EPROMs from the TWIN-68 Rev C board recovered from Ashford Poly.

The board features two 68000 CPUs clocked at 12 MHz sharing a dual-ported 128KB static RAM bank.
CPU #0 handles host bus interfacing and DMA, while CPU #1 is dedicated entirely to a 16-bit MAC (multiply-accumulate) unit.

Schematic diagram in ASCII uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/twin68_array.asc.

-- 
Seo-yeon Petrov
Tape trading list upon request. SASE required for international mail.

From lweber@illinois.edu Mon Nov 13 13:34:13 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!illinois!lweber
From: lweber@illinois.edu (Liam Weber)
Newsgroups: comp.sys.m68k
Subject: Re: Question: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1995Nov13.133413.6743@illinois.edu>
Date: Mon, 13 Nov 1995 13:34:13 GMT
References: <1995Nov13.105413.6066@purdue.edu>
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In article <1995Nov13.105413.6066@purdue.edu>, spetrov@purdue.edu (Seo-yeon Petrov) writes:
> Managed to dump the 27256 EPROMs from the TWIN-68 Rev C board recovered from Ashford Poly.
> The board features two 68000 CPUs clocked at 12 MHz sharing a dual-ported 128KB static RAM bank.

Socket U14 was probably for the decryption key lookup table. Without that EPROM, CPU #1 is running in an idle loop.

-- 
=== Liam Weber ===
Dept of Electrical Engineering, University of Illinois Urbana-Champaign
"Hardware is temporary. The signal survives."

From jramirez@demon.co.uk Tue Nov 14 11:16:13 1995
Path: ashpoly!cascade!transat!eunet-fr!teletel!demon!jramirez
From: jramirez@demon.co.uk (Ji-woo Ramírez)
Newsgroups: comp.sys.m68k
Subject: Re: Question: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1995Nov14.111613.6745@demon.co.uk>
Date: Tue, 14 Nov 1995 11:16:13 GMT
References: <1995Nov13.105413.6066@purdue.edu> <1995Nov13.133413.6743@illinois.edu>
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In article <1995Nov13.133413.6743@illinois.edu>, lweber@illinois.edu (Liam Weber) writes:
> Socket U14 was probably for the decryption key lookup table. Without that EPROM, CPU #1 is running in an idle loop.

Tom from Ashford Poly owns the physical board! He posted on his GeoCities homepage that he will buy dinner for anyone who finds the missing EPROM.

-- 
Ji-woo Ramírez | jramirez@demon.co.uk
PGP Key fingerprint: 5416 B51E 2C40 C59F
"Keep the channels open."