From vramirez@cam.ac.uk Sun Nov 20 07:27:13 1994
Path: ashpoly!cascade!mxgate!coyoacan!cam!vramirez
From: vramirez@cam.ac.uk (Valeria Ramírez)
Newsgroups: comp.sys.m68k
Subject: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1994Nov20.072713.2594@cam.ac.uk>
Date: Sun, 20 Nov 1994 07:27:13 GMT
Organization: University of Cambridge Computer Laboratory
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Managed to dump the 27256 EPROMs from the TWIN-68 Rev C board recovered from Ashford Poly.

CPU #0 handles host bus interfacing and DMA, while CPU #1 is dedicated entirely to a 16-bit MAC (multiply-accumulate) unit.
Disassembling ROM #0 reveals an initialization routine that checks for a hardware dongle marked 'ORION-ENC-84'.

One 28-pin EPROM socket (labeled U14) is completely empty. What firmware was supposed to be in that socket?

-- 
Valeria Ramírez -- University of Cambridge Computer Laboratory
"Marcus is not one man."

From vcampbell@unam.mx Sun Nov 20 11:58:13 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!unam!vcampbell
From: vcampbell@unam.mx (Valeria Campbell)
Newsgroups: comp.sys.m68k
Subject: Re: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1994Nov20.115813.5035@unam.mx>
Date: Sun, 20 Nov 1994 11:58:13 GMT
References: <1994Nov20.072713.2594@cam.ac.uk>
Organization: Universidad Nacional Autónoma de México (DGSCA)
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In article <1994Nov20.072713.2594@cam.ac.uk>, vramirez@cam.ac.uk (Valeria Ramírez) writes:
> Managed to dump the 27256 EPROMs from the TWIN-68 Rev C board recovered from Ashford Poly.
> CPU #0 handles host bus interfacing and DMA, while CPU #1 is dedicated entirely to a 16-bit MAC (multiply-accumulate) unit.

The MAC unit looks like a precursor to the DSP56001 that Motorola put in the NeXT and Atari Falcon.

-- 
Valeria Campbell
Opinions expressed are solely my own and not those of Universidad Nacional Autónoma de México (DGSCA).
------------------------------------------------------------

From astewart@purdue.edu Tue Nov 22 12:03:13 1994
Path: ashpoly!bigsur!pacrim!jpgate!kamome!purdue!astewart
From: astewart@purdue.edu (Andrei Stewart)
Newsgroups: comp.sys.m68k
Subject: Re: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1994Nov22.120313.8326@purdue.edu>
Date: Tue, 22 Nov 1994 12:03:13 GMT
References: <1994Nov20.072713.2594@cam.ac.uk>
Organization: Purdue University Engineering Computer Network
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In article <1994Nov20.072713.2594@cam.ac.uk>, vramirez@cam.ac.uk (Valeria Ramírez) writes:
> Managed to dump the 27256 EPROMs from the TWIN-68 Rev C board recovered from Ashford Poly.
> CPU #0 handles host bus interfacing and DMA, while CPU #1 is dedicated entirely to a 16-bit MAC (multiply-accumulate) unit.

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

-- 
Andrei Stewart -- Purdue University Engineering Computer Network
"Measuring a record you own is listening, not piracy."