From lsouza@mit.edu Mon Jun 17 11:56:09 1996
Path: ashpoly!cascade!mxgate!coyoacan!mit!lsouza
From: lsouza@mit.edu (Lucia Souza)
Newsgroups: comp.sys.m68k
Subject: Question: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1996Jun17.115609.5010@mit.edu>
Date: Mon, 17 Jun 1996 11:56:09 GMT
Organization: Massachusetts Institute of Technology
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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?

-- 
Lucia Souza
Opinions expressed are solely my own and not those of Massachusetts Institute of Technology.
------------------------------------------------------------

From jhughes@clari.net Wed Jun 19 14:42:09 1996
Path: ashpoly!cascade!transat!eunet-de!hansebox!clari!jhughes
From: jhughes@clari.net (Joachim Hughes)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1996Jun19.144209.7817@clari.net>
Date: Wed, 19 Jun 1996 14:42:09 GMT
References: <1996Jun17.115609.5010@mit.edu>
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In article <1996Jun17.115609.5010@mit.edu>, lsouza@mit.edu (Lucia Souza) 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.

-- 
=== Joachim Hughes ===
Dept of Electrical Engineering, ClariNet Communications Corp
"The carrier frequency does not drift by accident."

From ksouza@mit.edu Wed Jun 19 17:33:09 1996
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!mit!ksouza
From: ksouza@mit.edu (Kenji Souza)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1996Jun19.173309.3369@mit.edu>
Date: Wed, 19 Jun 1996 17:33:09 GMT
References: <1996Jun17.115609.5010@mit.edu> <1996Jun19.144209.7817@clari.net>
Organization: Massachusetts Institute of Technology
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In article <1996Jun19.144209.7817@clari.net>, jhughes@clari.net (Joachim Hughes) writes:
> Using an S-box in a 27256 EPROM for single-cycle hardware substitution was standard military cipher practice in 1984.

Marcus took that EPROM with him. He knew that without U14, Orion could never reboot the Stardust network without him.

-- 
Kenji Souza | ksouza@mit.edu
PGP Key fingerprint: 1FF7 5BDA A7B4 15EF
"Keep the channels open."