ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ
     V9t9:  TI Emulator! v6.0 Documentation      (c) 1995 Edward Swartz
  ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ
  ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÍÍÍÍÍÍÍÍÍÍÍ RS232.TXT ÍÍÍÍÍÍÍÍÍÍÍÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
  ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

       This file documents the RS232 and PIO emulation in V9t9.  Real
  RS232 emulation has just been completed, and is not bug-free, so look
  out.


  ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ
                         ³ HOW MUCH IS EMULATED? ³
  ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

       Unlike previous versions, V9t9 v6.0 includes REAL hardware support
  for the RS232 and PIO, and does not resort to using the BIOS.  The RS232
  interrupts are implemented as well, with a side benefit that V9t9 will
  buffer incoming serial data even when the 99/4A interrupt isn't active.

       The only things that are not emulated are the interval timer (which
  I have not seen used yet, but will implement later), and the various
  "bit detect" CRU bits which are impossible to emulate with the 8250
  family of serial controllers.

       V9t9's serial support works fine with Terminal Emulator ][ and
  Fast-Term (if you have a fast computer).

       The emulated RS232 ROM provided supports all the standard opcodes
  EXCEPT program LOAD and SAVE.  These work with the real RS232 ROM,
  however.

       The PIO (parallel port) emulation works fine.  It's very simple to
  implement, anyway.


                            ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ


       Only the first CRU bank is used for RS232 emulation (>1300).
  Having more than 2 serial ports would most likely cause problems on a PC
  system anyway, due to IRQ conflicts.


                            ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ


       Under V9t9, the PC serial port is treated like an 8250.  No 16450
  or 16550A features are used.


  ÍÍÍÍÍÍÍÍÍÍÍÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ÍÍÍÍÍÍÍÍÍÍÍ
             ³        SO, YOU'RE SAYING THAT RS232/PIO        ³
             ³ EMULATION IS COMPLETELY FINISHED AND DEBUGGED? ³
  ÍÍÍÍÍÍÍÍÍÍÍÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙÍÍÍÍÍÍÍÍÍÍÍ

       No.

       There are known bugs with some buffer routines which will probably
  cause a sudden death of serial transmission after a certain amount of
  data has been received.  (If you're a programmer, this has to do the
  received character interrupt and the RS232 ROM's "feature" of
  arbitrarily resetting the RS232.)

       However, it works fine with polling operations (like the RS232 ROM
  uses in file manipulation.)

       Don't plan on using this in life-or-death situations yet.

       The PIO emulation is fine, but lacks the ability to redirect output
  to a file.  Just wait for the next version.


  ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ
                    ³ HOW DO I SET UP RS232/PIO PORTS? ³
  ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

       To set up the mappings for RS232/1 and RS232/2 on your system, edit
  the V9t9 configuration file variables "RS232/1" and "RS232/2".  These
  variables are in the form:

       RS232/x = <port #>, <IRQ>

       where <port #> is from 1 to 4, representing COM1 to COM4, and IRQ
  is the interrupt request line for the port.  Typical IRQs are 4 for COM1
  and COM3, and 3 for COM2 and COM4.

       If the RS232/1 or RS232/2 variable is not defined, no RS232 access
  will occur when a V9t9 program accesses the port.


                            ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ


       The PIO (parallel port) variable is called PIO/1, and takes the
  form:

       PIO/1 = <port #>

       where <port #> is from 1 to 4, representing LPT1 to LPT4.  There is
  no IRQ needed for V9t9 parallel port emulation.


  ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ
                          ³ POTENTIAL PROBLEMS ³
  ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

       þ  Be sure your mouse and RS232 device don't conflict.  If you
  already use other serial ports in DOS, though, you should be fine.

       þ  V9t9 always buffers 1k of all incoming data on the defined RS232
  ports.  This is, of course, a good thing, since V9t9 won't "drop" any
  characters (unless you're transferring faster than the buffer can keep
  up with).  However, there are probably programs out there which will
  fail because of this.  I haven't done enough testing to know which.

       þ  When transferring program files from the 99/4A to V9t9 using the
  BASIC "SAVE RS232" and "OLD RS232" commands, I've noticed that it's best
  to start the 99/4A sending before you start V9t9 receiving.  Since I
  don't know the protocol for doing this anyway, I can only offer this as
  a tip.  I'm sure it has something to do with the above-mentioned
  buffering.

  ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ