Difference between 6809's

[Gerry Dahl]

Hi,
I have a piece of equipment that needs the 68B09P CPU.
I have tried three different 68A09EP CPU's and they won't work.

I have two of the these pieces of equipment and the results
are the same on each one.

Has anyone seen this or know why this is?

Please let me know.
Thanks.

Gerry Dahl

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[Geoffrey G. Rochat]

>I have a piece of equipment that needs the 68B09P CPU.
>I have tried three different 68A09EP CPU's and they won't work.
>
>I have two of the these pieces of equipment and the results
>are the same on each one.
>
>Has anyone seen this or know why this is?

It's the 'E' in there that's the first problem, the 'B' vs. 'A' that's
the second. Motorola made three speed grades of 6809, the straight 6809
at 1MHz, the 68A09 at 1.5MHz and the 68B09 at 2MHz. So what you're
trying to do is put a slow chip in a fast socket, and that's not likely
to work too well. But Motorola also made 6809s in two different
pinouts. The non-'E' pinout has an on-board oscillator, expects to see
a crystal across two particular pins and drives clock to the rest of the
system. The 'E' pinout has no on-board oscillator and expects to
receive an external clock. (There are also a couple of control signals
that differ between the 'E' and non-'E' pinouts as well, but I'd have to
do some serious digging to remember the details. Just the difference in
clocking alone would be enough to keep the substitution from working on
your board.) So you're also using the wrong pinout flavor of the chip.

In summary, of the six flavors of the 6809 Motorola produced (and let's
not get started on the CMOS 6309 superset variants that Hitachi came up
with...), you're trying to replace one flavor with an incompatible
flavor. You're going to need a 68B09 non-E part. BG Micro
www.bgmicro.com ) advertises 68B09 chips for $4. If that doesn't work
out, try Bob Garolfalo at Unicorn Electronics
www.unicornelectronics.com ). He doesn't list them in his catalog, but
he can probably get some for you. Finally, as of this writing Mouser
Electronics ( www.mouser.com ) claims to have 21 STMicro EF68B09P chips
(STMicro second-sourced the 6809 from Motorola and, AFAIK, is the only
manufacturer still producing them) in stock, stock number 511-EF68B09P,
$4.74 each.

[Klaus-Moretto]

MC68B09P CPU works whith 2 MHz clock
MC68A09 work only 1.5MHz.

Cleto Azzani
IPSIA MORETTO BRESCIA ITALY
azz...@ipsiamoretto.it

Gerry Dahl <gerry...@yahoo.com> wrote in message
8c64353137f93b2c901...@mygate.mailgate.org...

[Pierre Tricot]

Yes, the A or B is related to maximum clock rate but I think the
problem lies in the E suffix
The 6809E has different pin-out for clock generation.

Klaus-Moretto a écrit :

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Pierre TRICOT
Maitre de Conférences ENSEM
Electronique, Informatique Industrielle
Tél. +33 (0)3 83 59 57 37