Anyone ever play with their MSI88/e
- Hi guys,
I have 4 MSI-88/e's sitting on my "hobby" shelf. I haven't opened
them all, but I just opened one in addition to the 1802, this one has
32K in static RAM and a 28-pin chip I presume is a mask ROM that's
probably 8K or 16K, but I'm not sure. A few years ago I tried to burn
a ROM with a simple program to toggle the Q line but nothing happened.
Probably because of my inexperience with the 1802. I figure with 32K
ram to play with, and maybe 8K ROM, it might be possible to burn a ROM
replacement and actually make this into a hackable little machine.
I think the Q line goes to the connector already, and I suspect some
serial comm would be pretty easy to set up (if not directly, then by
kludging in a MAX232 chip or one of the new simpler cousins. WIth a
good monitor resident and some serial capability would facilitate
exploring the rest of the memory map, which could be fun.
Has anyone made any headway on this?
PS, I just picked up the 24K memory board and felt a huge static shock
:-( After 8 years I can't get used to the difference between Houston
- I poked at the existing rom code once from a disassembly listing but I've
never seen one in person. Are you able to replace the rom completely with
your own chip? You could maybe start with a tight loop that you could pick
up with just a multimeter on the address lines.
If you look back in the archives on the web site you can find my notes and
comments from others. I'd be happy to help poke if you're interested and I
imagine I still have the disassembly listing and lee hart's schematic.
----- Original Message -----
From: "bill_rowe_ottawa" <bill_rowe@...>
Sent: Friday, November 12, 2004 10:39 PM
Subject: [cosmacelf] As someone suggested, the MSI/88e is programmed in
>As someone suggested, the MSI/88e is programmed in Forth.
> Either that or some similar sort of threaded subroutine system.
> Poking through the code it looks like after some I/O initialization
> in a routine at 1F60, it settles down in a FORTH type dispatcher
> loop at 0011. The interpreter program counter looks D and the first
> instruction is at 1EEF, an x'37' there drives a new il routine at
> I know I'm talking to myself, but it helps!
> I'd still be interested in any I/O information. So far it looks
> like it initializes ports 1, 2, and 4 with 0s. It's interested in
> the bottom 2 bits of port A and it might be looking for serial data
> or some sort of high-low-high transition on the high bit of port E.
> It also sends 05 and 01 to port 6 and then looks for data on ports 8
> & 9.
> Visit the COSMAC ELF website at http://www.cosmacelf.com
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