[Coco] Checking/Testing a 68B09P

[Ron Delvaux]

Is there a coco group or club left in Phoenix?
Im moving there in august... Have a ton of coco stuff coming with me...

----- Original Message ----- 
From: <jdaggett at gate.net>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Sunday, July 01, 2007 9:27 PM
Subject: Re: [Coco] Checking/Testing a 68B09P


> On 1 Jul 2007 at 10:20, Andrew wrote:
> 
>> All:
>> 
>> 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?).
>> 
> **************************
> 
> The HD68B09 is the same chip as an MC68B09. Just different fabrication 
> facilities and companies. Correct that the HD68B09 is made by Hitachi as a 
> second source. The B version is a 2MHz part. IF t he date code is significantly 
> new,  say post 1986/87 time frame the MC/HD68B09 could run with a buss speed 
> of about 3 MHz.
> 
>> 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.
>>
> ***************
> 
> Pins 33 through 39 are different between the MC/HD68B09 and the 
> MC/HD68B09E. The differences are significant that would require major rewireing 
> of the COco motherboards to use a MC/HD68B09. 
> 
> 
>> 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 them).
>> 
>> 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.
>> 
> ***********************
> 
> Yes you could build a breadboard with a simple program in a ROM and test the 
> parts. You  cou ld even build a breadboard to plug into a COco to test the parts. I 
> would recommend a Coco 1 or a Coco2 that  has the MC68B09E socketed. On 
> the breadboard you would need to have a crystal that is 4 times the .89MHz clock 
> speed. That would wire to pins 38 and 39. Those pins on the breadboard would 
> not wire to the socket on the Coco. Also pins 33, 34, 35 and 36 would not wire to 
> the socket of the Coco. The rest are the same. 
> 
> james
> 
> 
> 
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