28 May
2005
28 May
'05
12:03 a.m.
I tried replacing the dead National Semoconductor MM5740AAE/N keyboard
encoder chip on this Datanetics keyboard with an MM5740AAC/N thinking the
C might just be some minor revision or whatnot and shouldn't make a
difference. Well, I'm not sure if there is some greater thing wrong with
this computer, but the keys don't map properly:
Key => 1 2 3 4 5 6 7 8 9 0 : -
Chr -> R F ^ A I U Y M C O S K
D'oh! I can't find any data for this chip. Does anyone know if in fact
the AAC is different from the AAN? Anyone got data?
Anyone got a spare MM5740AAE/N?
--
Sellam Ismail Vintage Computer Festival
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8:29 a.m.
On Sat, 28 May 2005, Eric Smith wrote:
Actually. it's AAE (the right one) vs. AAC (the wrong one I have). But
anyway, that explains things!
So, I'm looking for an MM5740AAE/N...
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
D'oh! I
can't find any data for this chip. Does anyone know if in fact
the AAC is different from the AAN? Anyone got data?
Yes, the "AAE" or "AAN" is the ROM mask code. 
10:08 a.m.
From: "Vintage Computer Festival" <vcf at siconic.com>
Sent: Saturday, May 28, 2005 10:29 AM
On Sat, 28 May 2005, Eric Smith wrote:
Actually. it's AAE (the right one) vs. AAC (the wrong one I have). But
anyway, that explains things!
So, I'm looking for an MM5740AAE/N...
--
Sellam Ismail Vintage Computer
Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger
http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage
mputers ]
[ and academia at www.VintageTech.com || at
http://marketplace.vintage.org ]
You can always wire in a Flash ROM to remap the characters.
Randy
www.s100-manuals.com
D'oh!
I can't find any data for this chip. Does anyone know if in
fact
the AAC is different from the AAN? Anyone got data?
Yes, the "AAE" or "AAN" is the ROM mask code. 
4:37 p.m.
I tried replacing the dead National Semoconductor MM5740AAE/N keyboard
encoder chip on this Datanetics keyboard with an MM5740AAC/N thinking the
C might just be some minor revision or whatnot and shouldn't make a
difference. Well, I'm not sure if there is some greater thing wrong with
this computer, but the keys don't map properly:
Key => 1 2 3 4 5 6 7 8 9 0 : -
Chr -> R F ^ A I U Y M C O S K
D'oh! I can't find any data for this chip. Does anyone know if in fact
the AAC is different from the AAN? Anyone got data?
My guess, based on similar encoder chips in the past, is that there's an
intenral mask-programmed ROM that translates between the hardware keycode
(i.e. the row and column of the matrix, maybe also the shift and control
key status) and the code sent out to the rest of the computer. And that
the AAC/AAN/... suffix identifies what the programming of that ROM is.
If it sents parallel data to the rest of the machine, you may be able to
insert a programmed EPROM between the keyboard encoder and the rest of
the machine to re-map the keycodes. But I'd not want to try that without
schematics.
-tony
7144
days inactive
7147
days old
5 comments
5 participants
participants (5)
-
ard＠p850ug1.demon.co.uk -
cctalk＠randy482.com -
eric＠brouhaha.com -
jdbryan＠acm.org -
vcf＠siconic.com