Dan, Bob, Brian (and anyone who cares :-))
The 74L123 is listed in the schematic, I received assistance from Steve
Shepard of AltairManuals.com.
I have a 1-6X motherboard too. I thought that because the system
has the round toggle switches that it was the "680" and that
the flat toggle switch version was the "680b", but I don't
believe it works that way...ANyone know for sure how to distinguish
between the two?
I plan to use a terminal, so I don't need the extra Baudot
circuitry. Being optimistic, I hope that this computer is simply
missing the 74L123, and that the circuity is otherwise intact for a 1200
baud 2 stop-bit terminal. I plan to check the I/O circuitry with a
magnifying glass just in case.
I plan to contact
for the chip. I may have one on another system I can borrow, I have not found one yet in the easy to find areas of my inventory of chips.
At 08:49 AM 3/2/2007 -0500, you wrote:
Hey man, I don't know which documentation you guys are reading,
I suspected you had downloaded the 680b docs already.
How can the 74LS74 can be mistaken for a 74L123.at location L ?
Maybe thats on the 8800--I don't have that manual
I've been checking my original docs with all my notes from when I built
this back then.
My schematics are dated 5/4/76, rev 1-6X mainboard
I have a 680b too, which is what you have as best as I can tell.
I double checked my assembly docs and parts list too.
It also states the 74LS74 is only needed if you use a Baudot terminal.
I suppose your using a standard RS232 terminal,right ?
There's 3 different sets of parts for the I/O configuration.
It's on pg.16,29,30 of the assembly manual.
I scanned it in case nobody has it.