Date: Tue, 10 Dec 1991 22:28 MDT
From: Joe Doupnik <JRD@cc.usu.edu>
Subject: SLIP Packet Driver
To: nelson@sun.soe.clarkson.edu
Cc: fdc@watsun.cc.columbia.edu
 
First, while getting SLIP to work in the next version of MS-DOS Kermit (v3.12)
I discovered that SLIP8250.COM has self inflicted wounds (loses interrupts).
So I did some quick work to sooth it into performing well.  I'll send you the
code and you can do some sanding and painting of it.  Basically, the writers
went overboard playing with 16550A UARTs and forgot that most UARTs lose the
transmit buffer empty interrupt when others occur.  I chopped out all that
xmtr code and put in a straight, simple, unqueued, send a char non-interrupt
driven transmitter and it works just fine, thankyou.
 
Date: Mon, 16 Dec 1991 21:32 MDT
From: Joe Doupnik <JRD@cc.usu.edu>
Subject: Revised SLIP8250 Packet Driver core
To: nelson@cheetah.ece.clarkson.edu
cc: fdc@watsun.cc.columbia.edu
 
Russ,
 
Here's the SLIP8250 file, revised to make it work dependably. There
are four changes:
 
1. Eliminate the use of transmitter holding register empty interrupts
   because they can be lost during processing of receiver interrupts. That loss
   stops the data exchange. My simpler method works fine.
 
2. Along with that we lose the large buffer for transmitted characters
   and the messy code dealing with these two items.
 
3. Remove the transmitter buffer size from the command line.
 
4. And ensure code lines do not exceed 80 bytes (preferrably 78).
 
The version number is bumped from 5 to 6. You might want to give the file a
new name because of the change to the command line: the send_buf_size
parameter has been eliminated (previously it was before recv_buf_size).  Here
is the new command-line format:
 
SLIP8250 [-n] [-d] [-w] packet_int_no [-h] [driver_class] [int_no]
  [io_addr] [baud_rate] [recv_buf_size]
 
Note: All parameters are given on one line, in the order shown.  Trailing
arguments (after packet_int_no) can be omitted.  The defaults are:
 
  driver_class  = SLIP (Class 6)
  int_no        = 4 (for IRQ 4)
  io_addr       = 03f8h (for COM1)
  baud_rate     = Whatever the port is presently set to
  recv_buf_size = 3000
 
The driver_class should be SLIP, KISS, AX.25, or a number. A 3000 byte receive
buffer is about twice as large as most programs need so experimenting is ok.
 
-h enables hardware handshaking (RTS/CTS).  Software flow control (Xon/Xoff)
is not available.
 
Run SLIP8250 from the DOS prompt, or from your AUTOEXEC.BAT file.  Example: 
 
  slip8250 0x60 SLIP 4 0x3f8 19200 3000
 
Joe D.