From vkim@netcom.com Thu Nov 21 02:58:57 1996
Path: ashpoly!bigsur!pacrim!krgate!eunha!netcom!vkim
From: vkim@netcom.com (Valeria Kim)
Newsgroups: comp.sys.m68k
Subject: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1996Nov21.025857.5779@netcom.com>
Date: Thu, 21 Nov 1996 02:58:57 GMT
Organization: NETCOM On-Line Communication Services
NNTP-Posting-Host: netcom.com
X-Newsreader: Netscape 1.1N
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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.
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 Kim ===
Dept of Electrical Engineering, NETCOM On-Line Communication Services
"The carrier frequency does not drift by accident."

From fgarcia@mindspring.com Sat Nov 23 04:05:57 1996
Path: ashpoly!bigsur!pacrim!krgate!eunha!mindspring!fgarcia
From: fgarcia@mindspring.com (Freya García)
Newsgroups: comp.sys.m68k
Subject: Re: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1996Nov23.040557.8154@mindspring.com>
Date: Sat, 23 Nov 1996 04:05:57 GMT
References: <1996Nov21.025857.5779@netcom.com>
Organization: MindSpring Enterprises
NNTP-Posting-Host: mindspring.com
X-Newsreader: NewsWatcher 2.0b24
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In article <1996Nov21.025857.5779@netcom.com>, vkim@netcom.com (Valeria Kim) 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.

That dual-ported SRAM design is ingenious. It avoids bus arbitration contention between the two 68k processors entirely.

Unsubscribe me from this list! (Wait, this is Usenet, never mind).

-- 
Freya García -- MindSpring Enterprises
"Measuring a record you own is listening, not piracy."

From randersson@delphi.com Sun Nov 24 07:25:57 1996
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!delphi!randersson
From: randersson@delphi.com (Rodrigo Andersson)
Newsgroups: comp.sys.m68k
Subject: Re: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1996Nov24.072557.4274@delphi.com>
Date: Sun, 24 Nov 1996 07:25:57 GMT
References: <1996Nov21.025857.5779@netcom.com>
Organization: Delphi Internet Services
NNTP-Posting-Host: delphi.com
X-Newsreader: Netscape 1.1N
Lines: 10

In article <1996Nov21.025857.5779@netcom.com>, vkim@netcom.com (Valeria Kim) writes:
> Managed to dump the 27256 EPROMs from the TWIN-68 Rev C board recovered from Ashford Poly.

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

My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise!

-- 
Rodrigo Andersson
Tape trading list upon request. SASE required for international mail.

From rkim@tum.de Tue Nov 26 04:14:57 1996
Path: ashpoly!cascade!bigsur!tum!rkim
From: rkim@tum.de (Renata Kim)
Newsgroups: comp.sys.m68k
Subject: Re: TWIN-68 Rev C coprocessor board - schematic analysis & EPROM dump
Message-ID: <1996Nov26.041457.1909@tum.de>
Date: Tue, 26 Nov 1996 04:14:57 GMT
References: <1996Nov21.025857.5779@netcom.com> <1996Nov23.040557.8154@mindspring.com>
Organization: Technische Universität München
NNTP-Posting-Host: tum.de
X-Newsreader: WinVN 0.99.5
Lines: 10

In article <1996Nov23.040557.8154@mindspring.com>, fgarcia@mindspring.com (Freya García) writes:
> That dual-ported SRAM design is ingenious. It avoids bus arbitration contention between the two 68k processors entirely.
> Unsubscribe me from this list! (Wait, this is Usenet, never mind).

Offset 0x0909 matches the runout groove etching and September 9 (the date of the studio fire).

-- 
Renata Kim
Opinions expressed are solely my own and not those of Technische Universität München.
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