[vcf-midatlantic] BYT-8 MPU

Jeff Galinat jgalinat at gmail.com
Tue Apr 24 21:37:26 EDT 2018

On Tue, Apr 24, 2018 at 6:24 PM Mike Loewen via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

>     I have what appears to be the CPU board for a Byte Shop BYT-8:
> http://q7.neurotica.com/Oldtech/S100/ByteMPU-2.jpg
>     BYTE 4-76 MPU  C1000-1001  ASSY REV A
>     It appears to be missing a ROM chip, and has definitely been hacked on
> (weird voltage regulator or transistor in lower left).
>     Is it worth putting this up for auction on the
> site-whose-name-shall-not-be-mentioned?  I also have an unbuilt PCB.
> Mike Loewen                             mloewen at cpumagic.scol.pa.us
> Old Technology                          http://q7.neurotica.com/Oldtech/

> Hi Mike,
I have 2 of those boards, both built from blank boards.  One was obtained
from Jonathan and one was bought from the "un-named auction site". I feel
they are nice boards and are usually my go-to CPU board for testing other
things out.  You are not missing any ROMs, the leftmost 24 pin socket is
for a 8214 priority interrupt controller and the one just to the right of
that is for a 8212 I/O port/latch. The proper regulator in the lower left
corner should be a 79L05 (-5v in a TO-92 pkg) but my guess is who ever
built or repaired the board decided to use a 7905 in a TO-220 in it's place
and couldn't fit it neatly since it is much larger. Jonathan has shared
links to his docs for the board in the past including a manual & hi-res
schematic scan here => <http://filedump.glitchwrks.com/manuals/s100/byt_8/>.
If you are going to sell it, I would probably refit the proper regulator to
make it more attractive for a buyer.   I don't have a good idea on price on
a populated board, but the blanks boards I bought were in the $35 to $50
range.   I hope this helps a little.
Jeff Galinat

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