From krodriguez@hanse.de Tue Nov 28 22:12:04 1995
Path: ashpoly!bigsur!pacrim!jpgate!kamome!hanse!krodriguez
From: krodriguez@hanse.de (Kirsty Rodríguez)
Newsgroups: comp.sys.m68k
Subject: Question: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Nov28.221204.6302@hanse.de>
Date: Tue, 28 Nov 1995 22:12:04 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.

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

-- 
Kirsty Rodríguez
Tape trading list upon request. SASE required for international mail.

From kvasiliev@kth.se Thu Nov 30 19:12:04 1995
Path: ashpoly!cascade!mxgate!coyoacan!kth!kvasiliev
From: kvasiliev@kth.se (Kenji Vasiliev)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Nov30.191204.2710@kth.se>
Date: Thu, 30 Nov 1995 19:12:04 GMT
References: <1995Nov28.221204.6302@hanse.de>
Organization: Royal Institute of Technology, Stockholm
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In article <1995Nov28.221204.6302@hanse.de>, krodriguez@hanse.de (Kirsty Rodríguez) writes:
> 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.

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

-- 
Kenji Vasiliev <kvasiliev@kth.se>
*PLONK* filter active for trolls.
Macintosh IIfx - NetBSD 1.0