[Coladam] eBay auction

Rich Drushel drushel at apk.net
Sun Jun 14 18:01:31 CEST 2009

On Sun, June 14, 2009 12:18 am, Geoff Oltmans wrote:

> I asked the seller for more detailed pics. He's put a couple more up.

     I looked, they confirm that there are trimpots present, other stuff
for some kind of analog circuit.

> Looks like there are more components underneath the ribbon cable. One
> part is an LM567CN, which is described as a tone decoder. I also got
> him to take some closeups of the four chips in the center of the
> board. It looks like there might be a 5th underneath the ribbon.

     "Tone decoder"...hmmm...then possibly "TAPE SIM" means that the
analog circuitry section (near the DB-37 and above/under the ribbon
cable) is generating/decoding test tones at a particular frequency,
like what is encoding the data on a DDP.  If you have ever listened
to a tape in an audio tape deck (remembering to drill out certain
holes in the case so it will fit alignment pegs that audio tape decks
have), there are some pure tones, plus staticky-sounding stuff, for
each data block.  Sample DDP data in lieu of an actual tape drive...
an emulator for the read/write and/or servo boards (see my schematics

     Not enough of an electrical engineer to know from just the chips
that are present; I am speculating.  Hey, maybe this is part of the
prototyping stuff for the "wafer" or "stringy-floppy" tape drives that
were never used...explaining why none of the chips match those used
in the tape drive daughter boards.  Remember, for the tape drives,
the ADAMnet side (6801 and support chips) are on the ADAM logic board;
the servo and read/write boards are in the tape drive unit.

     *Dr. D.*

Richard F. Drushel, Ph.D.            | "They fell:  for Heaven to them no hope
Department of Biology                |  imparts / Who hear not for the beating
Case Western Reserve University      |  of their hearts."
Cleveland, Ohio  44106-7080  U.S.A.  |         -- Edgar Allan Poe, "Al-Aaraaf"

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