I don't know if there's room, but you could use the output on port EFh for 8 LEDs for diagnostic progress.
Sent from my iPhone Can we have the sense switch (IOBYTE) pegged to 0EFH to make life simple. Is used a lot in our earlier software. John All good ideas, especially the 8085 and the sense switch input. I wish the msdos board had a sense switch input.
Sent from my iPhone Some notes for Ver one... To gain some room on the board.... 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) 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 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
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~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~
Tom Lafleur
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