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From: knudsen@ihwpt.UUCP (mike knudsen)
Newsgroups: net.micro,net.micro.6809,net.micro.apple
Subject: Reading mask ROMs on ROM burner?
Message-ID: <1183@ihwpt.UUCP>
Date: Fri, 24-Oct-86 16:32:58 EDT
Article-I.D.: ihwpt.1183
Posted: Fri Oct 24 16:32:58 1986
Date-Received: Sat, 25-Oct-86 07:02:06 EDT
Distribution: net
Organization: AT&T Bell Labs, Naperville, IL
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Xref: watmath net.micro:15820 net.micro.6809:993 net.micro.apple:3327

Does anyone have any hints for reading mask-programmed
(not EPROM) ROMs on a professional ROM burner?
Specifically, these are Motorola SCM-series chips,
8K x 8 bits, with 24 pins.
I have some MCM-68766 24-pin EPROMS that are supposed to
be compatible with the above, in that the EPROMs can be
plugged into the mask-ROM's sockets in the computer
and will work.  A single pin on these EPROMs is used as
CE* (chip/read enable) during usage, but is pulsed to
a high voltage when being programmed.
Supposedly that same pin is just CE* in the mask ROMs.

What's weird is that our Data I/O ROM blower with its 
Uni-Pak II, when set up to read/write the above EPROMs
(family/pin 25,29), won't read the mask ROMs -- it
gets Hex 44 in all locations.  Anybody know what to do?

The mask ROMs are Radio Shack DOS for my Color Computer--
I want to patch some bytes in them to improve the disk
step rates.  People read these ROMs fine on little
home ROM burners -- why can't the industrial-strength
units do it?	Thanks, mike k
-- 
Mike J Knudsen    ...ihnp4!ihwpt!knudsen
Bell Labs (AT&T)   (312)-979-4132 (work)
Nobody pays for my opinions, which are mine alone.
"A mind is a terrible thing to waste, but the pay is good."