AE RAMFACTOR CARD: Which controller IC is bad??

[sebugg@presby.edu (Stephen Buggie)]

              AE RAMFACTOR MEMORY CARD FOR IIE:
              IDENTIFYING THE BAD CONTROLLER IC
              HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH




I have two AE "Ramfactor" 1024K ram cards.  One works perfectly,
the other works good with 768K or less, but gives errors if filled
to 1024K.        The Eprom is labeled RF 1.4, so this is version 1.4
of RAMFACTOR.     RAMFACTOR is the slot #1-7 memory card by Applied
Engineering.

I can identify the bad chip by doing systematic "chip-swapping~" between the
boards, but could someone advise me which of the following chips is/are
MOST LIKELY to be at fault so that I could swap/test those ICs first:


-----------------------------------------------
TMS  LHP 8460  (looks like an EPROM)

74LS245          [two chips of this number]

734212  RF 1-Q   [two chips of this number]

714091   RF4BQ

052NNSS    RF5B-W


74LS11

74LS14

74LS74           [two chips of this number]

142HWDZ   C          RF6D-W

-----------------------------------------------


At the "keyboard" end of the card there are two jumpers, now closed.

All the other ICs are RAM chips, 256-12.  I do not think that bad RAMs
are at fault because I have already swapped the RAMs between the working
and non-working Ramfactors, and yet the fault persists.


Stephen Buggie    sebugg@presby.edu

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   ** S. Buggie  sebugg@presby.edu  IIgs/c/e Ph: (803) 833-8337, 833-1632 **
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