From ppetrov@cam.ac.uk Sat Aug 19 13:06:09 1995
Path: ashpoly!cascade!transat!ukc!fennimore!cam!ppetrov
From: ppetrov@cam.ac.uk (Pavel Petrov)
Newsgroups: comp.sys.m68k
Subject: Discussion: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1995Aug19.130609.6044@cam.ac.uk>
Date: Sat, 19 Aug 1995 13:06:09 GMT
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Looking at the bus architecture of the TWIN-68 board. Motorola engineers, please take a look.

At ROM offset 0x0909, the string 'M.H. // THE HATCH IS OPEN // ADVANCED ACOUSTICS LAB' is stored in ASCII.
CPU #0 handles host bus interfacing and DMA, while CPU #1 is dedicated entirely to a 16-bit MAC (multiply-accumulate) unit.

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

-- 
Pavel Petrov | ppetrov@cam.ac.uk
PGP Key fingerprint: D6E8 990A 604F 86C7
"Keep the channels open."

From dmuller@purdue.edu Sun Aug 20 11:07:09 1995
Path: ashpoly!cascade!mxgate!coyoacan!purdue!dmuller
From: dmuller@purdue.edu (Dong-hyun Müller)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1995Aug20.110709.7639@purdue.edu>
Date: Sun, 20 Aug 1995 11:07:09 GMT
References: <1995Aug19.130609.6044@cam.ac.uk>
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In article <1995Aug19.130609.6044@cam.ac.uk>, ppetrov@cam.ac.uk (Pavel Petrov) writes:
> Looking at the bus architecture of the TWIN-68 board. Motorola engineers, please take a look.
> At ROM offset 0x0909, the string 'M.H. // THE HATCH IS OPEN // ADVANCED ACOUSTICS LAB' is stored in ASCII.

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

-- 
Dong-hyun Müller
Tape trading list upon request. SASE required for international mail.

From nlarsson@cern.ch Tue Aug 22 08:46:09 1995
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!cern!nlarsson
From: nlarsson@cern.ch (Natalia Larsson)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1995Aug22.084609.7465@cern.ch>
Date: Tue, 22 Aug 1995 08:46:09 GMT
References: <1995Aug19.130609.6044@cam.ac.uk> <1995Aug20.110709.7639@purdue.edu>
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In article <1995Aug20.110709.7639@purdue.edu>, dmuller@purdue.edu (Dong-hyun Müller) writes:
> The MAC unit looks like a precursor to the DSP56001 that Motorola put in the NeXT and Atari Falcon.

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

PGP Public key available via finger or upon request.

-- 
Natalia Larsson | nlarsson@cern.ch
PGP Key fingerprint: 62A8 C2F3 93C3 1911
"Keep the channels open."