Date   : Tue, 15 Dec 1987109:34:00-MST
From   : "John A. Wright" <SAC.HQSAC-DOCT@E.ISI.EDU>
Subject: CP/M Devices

I am somewhat confused.  I have downloaded two terminal pgms for my
Osborn I that are supposed to run off the serial port.  Neither does.

In my reading, I have come across the explanation of the "STAT"
command which allows me to assign any physical device to a logical
device.  My problem is that I can't figure out form the book exactly
what that means.

According to the Ref manuel I have the following logical devices:

  CON: >> Keyboard + screen
  RDR: >> serial/parallel/ieee  (Can anyone tell me what a "reader" is)
  PUN: >>   "        "      "   (Can anyone tell me what a "punch" is)
  LST: >>   "        "      "

I have the following physical devices:

  TTY:
  CRT:
  BAT:
  UC1:
  PTR:
  UR1:
  UR2:
  PTP:
  UP1:
  UP2:
  LPT:
  UL1:

Does anyone have a simple explanation for all this, or even a not so
simple one would be a help.

From what I have found, the RS-232 (Serial) port and the 9 pin (modem)
port have about the same functions.  Book says "the modem and RS-232
interfaces are basically one and the same; the primary difference is
that many of the signal levels on the RS-232 connector are help
constant, while you can manipulate them using the modem connector."

It goes on further to say: "If all you need to do is read to and from
the modem/or serial port, simply change the IO BYTE indirectly by
using the CP/M STAT command..."

Seems to me I should be able to run a standard modem off the RS-232
port if I can change the IO BYTE.  Any ideas?

Thanks in advance.