[rescue] ADM3-A lower case ROM
shatle at nfldinet.com
Tue Dec 13 19:46:47 CST 2016
-------- Original Message --------
Subject: Re: [rescue] ADM3-A lower case
From: John Hudak <jjhudak at gmail.com>
Date: Tue, December 13, 2016 12:29 am
To: The Rescue List <rescue at sunhelp.org>
ahhh, a blast from the
past...SIgnetics 2513 character generator ROM.
These are as scarce as WOMs.
This fellow did a dump of the lower case character generator for the
also has a adapter board that uses a 2716 (you can still find them,
He also points out (incorrectly i believe) that the cycle time
is 400ns....I always remembered 450ns, and I double checked it in
Signetics data book. Unless LearSigler made some special arrangement
Signetics that I am unaware of.
In any event, you don't want to install that ROM incorrectly....Good
BTW, IIRC, the dip switches are the only thing that needs to be changed
accomodate the lower case ROM....I don't remember what dip switches they
I set the DIP switches and installed the ROM. When I turned on the
terminal, the whole screen was filled with "`" characters before the
When I started up the connected Sun machine, the terminal did
both upper and lower case characters, but the "`" characters remained
and appeared to fill out each new line, and text printed out by the
was followed by garbage characters - like "Login:nzzzz". Typed
correctly upper or lower as typed.
I removed the ROM and cleaned the legs of
the chip. I didn't clean the
socket, since I didn't have anything like DeOxit
handy. I did remove and
re-insert the ROM a couple of times.
When I removed
the ROM and set the DIPs back to the original setting,
the terminal worked
like normal in all upper case. Setting the DIPs to
force upper case, etc. when
the ROM was in always showed the bad
behavior though the characters were
upper/lower as you would expect from
the switch settings.
TL;DR - bad and
extra characters when the ROM chip is in, everything OK
when it's out.
barring a bad connection to the chip while it's in the socket, it
the ROM itself could be bad. I'll dig through the maint
manuals and see if I
can find anything related to this behavior. In the
meantime, any ideas from
the collective are welcome.
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