[Coco] Checking/Testing a 68B09P
keeper63 at cox.net
Sun Jul 1 13:20:08 EDT 2007
Yesterday, I picked up a set of 6809 40-pin DIP processors (from a local
Phoenix electronic junkstore - Apache Reclamation and Electronics). I
wondered if anyone could tell me whether they are worth keeping or not,
plus if there was a way to test them without using a real CoCo?
Of the lot, I have 6 pieces of HD68B09P, and one MC68B09P (I also found
a wierd floppy drive controller chip - FDC1795 - does anyone know
anything about this - I found a datasheet, but I am wondering if it
could be useful for building a more modern FDC board for an Altair I
have sitting waiting for restoration?).
I found data sheets for all of these parts - so, for the 6809 pieces,
they seem to be 1.5 MHz processors (B), plastic (P) - HD=Hitachi,
MC=Motorola. The spec sheets seem to be for all 6809 products, and they
say they are pin-compatible.
Unfortunately, none are of the 2 MHz variety for the CoCo 3...
They seem like they might make a good upgrade or replacement CPUs for
the CoCo 2 (they may even work in a CoCo 3?) - however, I don't know
what the condition of these chips are - they were stored on anti-static
foam, but were contained in a large mix of "junk" parts. None were
labeled as bad, but that doesn't mean anything.
Does anyone know how I could test these to verify that they work? I have
both a Color Computer 2 and 3, but I don't want to smoke these units
(they are my first computers from my youth - I try to take good care of
Is there any way I can build a simple perfboard test circuit that could
tell me "likely good"/"likely bad"? The datasheets don't give a sample
circuit (I suppose there is actually an "applications" datasheet or book
for 6809 reference designs?). I suspect that the simplest test design
might actually be quite involved - the 6809 is a microprocessor, after
all, and not a microcontroller - so I can imagine a bit of support
circuitry to be required.
I am not at a point where I can do this immediately, but knowing what to
do when I can get around to it would help.
-- Andrew L. Ayers
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