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Re: 8080a board

Some notes for Ver one...  To gain some room on the board....

As suggested before....

Use only 4 wire rs232 with max232a/tr202, removing need for +-12v ( 3 to 4 chip saving)
Move to 8085, no need for +12 or -5v, less support chip needed... ( ~2 chip saving)

Make board stand alone, no other boards needed to make it run... ( plus 1 chip)
Fix upper address and data lines to bus issues .  (Plus 2 chips)

New ideas...

Replace 8212's with 74als logic (~ 3 chip saving)

Replace ram chips with one larger chip, (wasting part of the chip to save room if needed) 64k x 8 or larger like an as6c4008 with a poor man's mmu if their room on board...(use output port?) like zeta board.... (~ plus 1 to 2 chip saving)

If room, allow room for a dip switch with pull-ups on input port.... (~ plus 1 chip)

Just my ideas from building the board....

i~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~i

Tom Lafleur

On Nov 19, 2014, at 8:00 PM, Crusty OMO <crus...@hotmail.com> wrote:

Opps, thanks for letting me know... I guess it's a cut n paste error or just an over sight.


Date: Wed, 19 Nov 2014 16:34:41 -0800
Subject: 8080a board
From: laf...@lafleur.us
To: crus...@hotmail.com


​It appears that UART1 at A5 is connected to COM1 port, P1/P2 on the  board, but the schematic say its connected to P3/P4​


~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~

Tom Lafleur