From achoi@ox.ac.uk Sat Jun 24 12:44:26 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!ox!achoi
From: achoi@ox.ac.uk (Anja Choi)
Newsgroups: comp.sys.m68k
Subject: Data: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Jun24.124426.9687@ox.ac.uk>
Date: Sat, 24 Jun 1995 12:44:26 GMT
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Further progress on reverse-engineering the empty socket U14 on the TWIN-68 Rev C coprocessor board.

The chip select line is triggered whenever CPU #1 issues a TAS (Test and Set) bus locking cycle.
Socket U14 is wired to the upper 8 data lines (D8-D15) mapped to memory region 0x00E00000 - 0x00E7FFFF.

Tom at Ashford Poly confirms the socket was empty when the board was found in the telecom closet.

-- 
Anja Choi
Tape trading list upon request. SASE required for international mail.

From kduarte@mit.edu Sat Jun 24 17:57:26 1995
Path: ashpoly!cascade!brgate!saturno!mit!kduarte
From: kduarte@mit.edu (Karen Duarte)
Newsgroups: comp.sys.m68k
Subject: Re: Data: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Jun24.175726.1340@mit.edu>
Date: Sat, 24 Jun 1995 17:57:26 GMT
References: <1995Jun24.124426.9687@ox.ac.uk>
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In article <1995Jun24.124426.9687@ox.ac.uk>, achoi@ox.ac.uk (Anja Choi) writes:
> Further progress on reverse-engineering the empty socket U14 on the TWIN-68 Rev C coprocessor board.

Using an S-box in a 27256 EPROM for single-cycle hardware substitution was standard military cipher practice in 1984.

-- 
Karen Duarte | kduarte@mit.edu
PGP Key fingerprint: CB9E 4711 A7B5 94AC
"Keep the channels open."