Richard Cini wrote:
Just a fun thing to do with the Z80MC and SIO card.
With some great detective work from Josh and a little bit of tinkering,
I was able to get the SIO connected to a Hayesmodem 300 and to get an
old CP/M program called “MODM221A” running. MODM221A is a derivative of
the original MODEM program from Ward Christensen.
What a cool idea! I still have my Hayes Smartmodem, and fondly remember using it to log onto various BBS's on my CP/M computer back in the 80's.
Using this combination, there are a few things to note.
First, you have to boot to the monitor and make sure that console input
is the bit-banger only, and then load CP/M manually. There’s probably a
way to permanently do this, but it would require modifying the system ROM.
If anyone figures it out, I can make a new ROM. There are a number of upgrades like this that I've been meaning to get into. (Where does the time go...)
Second, since DTR and RTS are used as address bits, the ACE
initialization in MODM221 has to disable DTR and RTS (or, if those are
needed, then the RAM needs to be reduced to 32K and 5V re-routed to put
it in the right place for the 32K RAM).
The 8250 has four output bits; DTR, RTS, OUT1, and OUT2. I supply a 128K RAM for U1; it only needs two extra address bits. I happened to use DTR and RTS (leaving OUT1 and OUT2 unused).
In hindsight, I could have used OUT1 and OUT2 for the extra address bits; that would leave DTR and RTS free to use normally for serial communications. Maybe I can do that on the next "spin" of the board.
I don’t have a BBS setup, but I do have all the parts
for it – a computer with a Digi 8-port serial board and an analog
telephone switch. So, that will be my next project.
I wish I knew more about the modern internet. It seems like it should be possible to setup a "modern" BBS that old CP/M computers can log into. The old modem would be replaced with a "black box" that connects to the internet instead of a phone line.
I've seen this done; but the "black box" is a PC, complete with keyboard and screen. In fact, you do everything on the PC itself. The CP/M computer is redundant.
Then there is the question of what the web pages on the internet look like that such a "BBS" accesses. They can't be the usual HTML, color, graphics, javascript, etc. if you expect a CP/M computer to deal with it. Examples I've seen may *look* like an old time terminal (like <> ) but in fact it's a page full of the usual HTML, javascript, CSS, etc.
Lee Hart
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
Lee Hart