From tpetrov@delphi.com Wed Apr 19 04:04:44 1995
Path: ashpoly!bigsur!pacrim!jpgate!kamome!delphi!tpetrov
From: tpetrov@delphi.com (Tobias Petrov)
Newsgroups: comp.sys.m68k
Subject: WTB/WTT: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Apr19.040444.8767@delphi.com>
Date: Wed, 19 Apr 1995 04:04:44 GMT
Organization: Delphi Internet Services
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Tracing the address decoder lines on the motherboard reveals what was supposed to be in socket U14.

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?

-- 
Tobias Petrov -- Delphi Internet Services
"Hardware is temporary. The signal survives."

From mnilsson@utexas.edu Wed Apr 19 15:46:44 1995
Path: ashpoly!cascade!bigsur!utexas!mnilsson
From: mnilsson@utexas.edu (Marta Nilsson)
Newsgroups: comp.sys.m68k
Subject: Re: WTB/WTT: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Apr19.154644.4263@utexas.edu>
Date: Wed, 19 Apr 1995 15:46:44 GMT
References: <1995Apr19.040444.8767@delphi.com>
Organization: University of Texas at Austin
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In article <1995Apr19.040444.8767@delphi.com>, tpetrov@delphi.com (Tobias Petrov) writes:
> Tracing the address decoder lines on the motherboard reveals what was supposed to be in socket U14.

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

-- 
Marta Nilsson -- University of Texas at Austin
"Tape doesn't lie at 02:14. Ears do."