Which PIC for emulator?

[Bill Shaw]

>I think we
>need to add a 74HC373 and a muxed address bus.
>

In my current project I'm using a 16C74's portD for the data bus and bits
from A and C as chip selects for the 373s and 244s.  I think it's the way
to go for the  emulator. Three '373s for the 18 address bits & misc bits,
one for the 8 data.

If all it's doing is managing the memory (I'd prefer flash to ram,  once
programmed it'll run without external help) it should easily fit in 4K
(even in C),  so the '874 should work,  and can be changed to a '877 later
if necessary.

I'm trying to talk my partner into changing to a '876 instead of the 14K
we're using in another project.  If I'm successful I'll buy the '877 pod
for my PicMaster.

>
>I've thought a bit about the software side.  Here's a proposal:  Give
>the emulator a simple ASCII command line interface.  Provide upload and
>download in Intel hex and Motorola S records.  Also support binary
>transfers using perhaps ZMODEM protocol.  This would allow the emulator
>to be controlled via just a terminal emulator.  Of course, a special
>software shell running on a laptop could still be written.  It would
>give ASCII commands to the emulator "under the hood".
>


Sounds OK,  Zmodem will be a PIA.  Hex & S records will work OK in a simple
terminal program.

bs