From jeriksson@hanse.de Fri Jul 22 13:43:50 1994
Path: ashpoly!cascade!brgate!saturno!hanse!jeriksson
From: jeriksson@hanse.de (Joachim Eriksson)
Newsgroups: comp.sys.m68k
Subject: Question: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1994Jul22.134350.4006@hanse.de>
Date: Fri, 22 Jul 1994 13:43:50 GMT
Organization: Hanse-Netzwerk Hamburg
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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.

Does anyone have a 27C256 EPROM marked 'MH-U14' or 'ORION-CRYPTO'?

-- 
Joachim Eriksson -- Hanse-Netzwerk Hamburg
"Row 14. No joke."

From hperez@u-tokyo.ac.jp Sun Jul 24 14:20:50 1994
Path: ashpoly!cascade!brgate!saturno!u-tokyo!hperez
From: hperez@u-tokyo.ac.jp (Hugo Pérez)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1994Jul24.142050.9733@u-tokyo.ac.jp>
Date: Sun, 24 Jul 1994 14:20:50 GMT
References: <1994Jul22.134350.4006@hanse.de>
Organization: University of Tokyo Department of Information Science
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In article <1994Jul22.134350.4006@hanse.de>, jeriksson@hanse.de (Joachim Eriksson) 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.

-- 
Hugo Pérez | hperez@u-tokyo.ac.jp
PGP Key fingerprint: 6262 9392 0C74 0F91
"Keep the channels open."