Gary, just checked my board. I can get back to Z80 from 80386 monitor (V1.84) with the “Z” command if the P36 jumper is in 1-2 position. However NOT SO if it’s in 2-3 position. The latter is utilizing the SMB V2 to pull down TMA1 rather than the 80386 onboard port. I will look into it, but meanwhile check software for both CPU’s. I bet there is a conflict with either the (old) IN Port option to switch CPU’s or the newer Output a bit method.
From: n8ve...@googlegroups.com [mailto:n8vem...@
googlegroups.com] On Behalf Of Gary Kaufman
Sent: Monday, February 2, 2015 5:27 AM
Subject: [N8VEM-S100:6179] Re: 80386 CPU Board
David and John -
I've read thru the '386 page dozens of times!
I have the SMB and can switch to the '386 board thru QIED, or output QOEE,01. Also the "W" and "O" commands both work. Unfortunately when I use "Z" to return the system hangs.
I can go back to the Z80 from the 6502, 8088 or 80286 boards fine.
I have P36 with 1-2 and 3-4 jumpered.
I do think it's likely a jumpering issue, but I'll also swap out all of the 74LS74's again once my Mouser order arrives. I've had a few flakey ones recently.
On Sunday, February 1, 2015 at 11:02:55 PM UTC-5, monahanz wrote:
Gary I have written up a few notes/tricks on hardware debugging these types of CPU boards:-
On Sunday, February 1, 2015 at 8:24:54 AM UTC-8, Gary Kaufman wrote:
I completed the 80386 board yesterday, and after some confusion (on my
part) getting the monitor configured and jumpered correctly on the
MS-DOS support board it's running nicely at 32mhz using an AMD 80386-33
I'm running into two issues, and wonder if anyone has encountered them.
When I try to return to the Z80 using the "Z" command it hangs.
I've tried using a TX486DLC/E-33GA but it hangs after printing the
initial monitor prompt (at both 16 and 32mhz).
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