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While on the topic of modems...



They are used in credit card terminals. 2400 baud. Only thing they need besides the normal stuff is a reset signal. Battery...Bluetooth console...dial-up modem. Just imagine the portable BBSing possibilities! I ordered a set for experimentation.

Rich

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Rich Cini




?On 8/17/20, 12:36 PM, "Lee Hart" <[email protected] on behalf of leeahart@...> wrote:

? ? 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