From tito@illinois.edu Wed Dec 14 23:06:57 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!illinois!tito
From: tito@illinois.edu (Tomas Ito)
Newsgroups: comp.sys.m68k
Subject: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1994Dec14.230657.4932@illinois.edu>
Date: Wed, 14 Dec 1994 23:06:57 GMT
Organization: University of Illinois Urbana-Champaign
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Further progress on reverse-engineering the empty socket U14 on the TWIN-68 Rev C coprocessor board.

Without U14, the board can track the 14.2 Hz carrier, but cannot descramble the binary payload of Nodes 11 through 14.
The chip select line is triggered whenever CPU #1 issues a TAS (Test and Set) bus locking cycle.

Did Marcus take the decryption EPROM with him when he left the lab?

-- 
Tomas Ito
Opinions expressed are solely my own and not those of University of Illinois Urbana-Champaign.
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From mvasiliev@uu.net Sat Dec 17 01:54:57 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!uu!mvasiliev
From: mvasiliev@uu.net (Marta Vasiliev)
Newsgroups: comp.sys.m68k
Subject: Re: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1994Dec17.015457.8724@uu.net>
Date: Sat, 17 Dec 1994 01:54:57 GMT
References: <1994Dec14.230657.4932@illinois.edu>
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In article <1994Dec14.230657.4932@illinois.edu>, tito@illinois.edu (Tomas Ito) writes:
> Further progress on reverse-engineering the empty socket U14 on the TWIN-68 Rev C coprocessor board.
> Without U14, the board can track the 14.2 Hz carrier, but cannot descramble the binary payload of Nodes 11 through 14.

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

-- 
Marta Vasiliev
Opinions expressed are solely my own and not those of UUNET Technologies, Falls Church VA.
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