1 May
2004
1 May
'04
10:35 a.m.
Everything on it is TTL except for one LSI IC marked
MCH-01. Anyone know what that might be?
Probably a character ROM.
Lee.
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1 May
1 May
3:51 p.m.
Everything on it is TTL except for one LSI IC
marked
MCH-01. Anyone know what that might be?
Probably a character ROM. 
2 May
2 May
1:44 a.m.
At 04:51 AM 5/2/04 +0100, you wrote:
How many pins does it have? Character generator ROMs tend to be 24 pin (or
maybe 28 pin). Is the 'MCH-01' marking a stuck-on label or marked
directly on the package?
I am suprised there's no RAM on this board, actually. That could be 16
pin packages, and thus mistaken for TTL.
The four columms of ICs on the RH side are 2114 SRAMs (GTEus no less.)
There are a total or 24 of them. They're 1k x 4 each so that makes a total
of 12k bytes of RAM. The large LSIC has 24 pins and th enumbers are marked
directly on the package.
It has four 74ls367 93 state buffers), four 74ls243 (Quad 3state bus
transeiver) and one 74ls00 (Quad 2 input NAND) that are in sockets. Any
idea why they'd be socketed but the rest aren't?
Joe
Everything on it is TTL except for one LSI IC
marked
MCH-01. Anyone know what that might be?
Probably a character ROM.
-tony
2:07 a.m.
On Sunday 02 May 2004 06:44, Joe R. wrote:
--snip--
It has four 74ls367 93 state buffers), four 74ls243
(Quad 3state bus
transeiver) and one 74ls00 (Quad 2 input NAND) that are in sockets. Any
idea why they'd be socketed but the rest aren't?
Typically manf. socketed chips they found failed more frequently - or chips
that where the most available version could be used - i.e., substitute a
74s00 or 7400 for a 74ls00, etc.
Lyle
--
Lyle Bickley
Bickley Consulting West Inc.
http://bickleywest.com
"Black holes are where God is dividing by zero"
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