	PC-VT version 8.0		USER Supported Software

					6 Feburary, 1985
					9067 Hillery Drive
					San Diego, CA 92126

Dear User of PC-VT;

	Enclosed  is  the  latest version of PC-VT and its documentation.  I
formatted your diskette double sided, 9 sectors per  track  (unless  it  was
already  formatted).   If you sent me a single sided diskette, I reformatted
it double sided if I could, otherwise, I was not able  to  get  all  of  the
files onto it.  PC-VT runs on the PC, the PCjr, and the PC AT under DOS 1.1,
2.0, 2.1, and 3.0.

	This  version  of  PC-VT contains both a Hayes compatible dialer and
XMODEM with CRC transfer capability.  It supports DOS 2 path  names.   PC-VT
now supports VT52 compatibility mode and ALT-F1 thru ALT-F10 as macro keys.  

	The  program itself is named PC-VT.EXE.  Place the supplied diskette
into one of your diskette drives.  Set the default diskette letter in DOS to
that drive.  If you have a modem which requires manual dialing, dial up  the
host  computer  and turn on the Modem.  Start the program by typing PC-VT in
response to the DOS prompt.  PC-VT comes preinitialized  to  communicate  at
1200  baud with 8 data bits, no parity, and 1 stop bit.  If these parameters
are not correct  for  your  installation  they  can  be  changed.   See  the
discussion  of  the  SETUP displays in the documentation for instructions on
how to change parameters.

	As  PC-VT  starts  up, it will initialize the COM port and establish
the connection to the modem.  The CRT will show the communications  display.
Lines  1  through  24 are used as the emulated VT100/102 screen which has 24
lines.  Line 25 is used as a status line.  The first thing that you will see
on line 25 is the word "ON LINE" and the version  number  of  PC-VT  in  the
lower left.  This indicates that PC-VT is operating normally and is ready to
communicate.   If  you  have  a Hayes or other compatible Modem, you can now
automatically dial the host's number.  Type CTRL-F9  to  enter  the  DIALING
display.  See Chapter 9 for detailed instructions on how to use this DIALING
facility.    Most   host   systems   require   that  the  terminal  initiate
communications so type ENTER.  Your host computer should now be  responding.
From this point on, PC-VT runs as a VT100/102 Video Terminal.

	You  can  use  PC-VT  on  the  IBM fixed disk as well.  There are no
special requirements.  Copy the program PC-VT.EXE to the fixed  disk.   Then
just start up PC-VT as described above.

	The  documentation  file is named PC-VT.DOC and can be copied to any
line printer.  It does not contain any special formatting  commands,  it  is
just  straight  text.   The  file  PC-VT.SUM  is just a short summary of the
capabilities of PC-VT.

	If  any  files  on  your  distribution disk have a "Q" as the second
character of the extension, they must be Unsqueezed with the USQ program.

	The  file PC-VT.CRD is a quick reference card for use with PC-VT.  I
would like to thank Richard C.  Rohrdanz of the Boston Computer Society  for
his help in creating PC-VT.CRD.

	I've also enclosed a set of XMODEM programs for the VAX running VMS.
They  were  written  by  Jim  Belonis of the University of Washington.  They
work.  I'll leave it up to you to upload them to the VAX and  compile  them.
Read  the  file  named  XMODEM.DOC.  These files are combined into a library
file named XMODVMS.LBR.  You  will  need  the  Library  Utility  (LU.EXE  or
LAR.EXE)  to  remove  them  from  the library file.  If they have a Q as the
second letter of the filetype, they are SQueezed.   Use  USQ  to  make  them
ASCII files.

	If  you  could  upload  PC-VT  and the XMODEM programs to your local
RBBS, I would appreciate your help.  You can  upload  PC-VT.EXE,  PC-VT.SUM,
PC-VT.DOC, and the XMODEM files on XMODVMS.LBR.

	One  useful piece of information : The older versions of PC-VT would
not pass CTRL-C on to the host computer because the CTRL-C  was  intercepted
by PC-DOS as a program termination command.  I have modified this version to
have  PC-DOS  ignore  CTRL-C  when reading from the keyboard.  Now CTRL-C is
sent to the host.   To  terminate  PC-VT  you  can  type  CTRL-F8  from  the
communications  display or still use CTRL-C from the SETUP, DIALING or MACRO
displays.  You should have the PC-DOS option BREAK set to OFF or else  PC-VT
will turn it off.

	SCRLOCK,   the   Extended  Batch  Language,  and  BACKSCRL  are  not
compatible with PC-VT.  SCRLOCK will not work well with DOS 2.0 in any case.
A general comment about PC-DOS "appendages": since there is no  way  that  I
can  try  every  patch to PC-DOS with PC-VT, if you are having problems, try
PC-VT with an unpatched DOS to see what happens.  The issue is how long some
of the attached programs run with interrupts turned off.  The comm  line  to
the  host  is  asynchronous.   If  PC-VT  cannot get back to the RS-232 port
before another character comes in, the old character is lost and an  overrun
error  is  generated.   This  type of problem is more apparent at the higher
baud rates but will also show up at 1200 baud.

	If  this  is an update for your site from an older version of PC-VT,
you should delete your old PARAMS.DAT file and use the one on this diskette.
The older PARAMS.DAT format may not  be  compatible  with  the  enhancements
added to this version of PC-VT.

	One  big  problem remains with this program and the IBM PC.  IBM (as
well as other vendors) unfortunately shipped a large number of PC  and  PCjr
with  8250 USART chips which do not function in the way expected by the 8259
Priority Interrupt Controller (PIC).  The 8250 are the  chips  which  handle
the  RS-232  ports.   The  problem  is  that sometimes, the interrupt is not
successfully passed between the 8250 and 8259.  Since PC-VT  uses  interrupt
driven  routines  for  speed,  that is a problem.  Basically what happens is
that when PC-VT is ready to send a character to the 8250 for transmission it
checks to see if the Transmitter Holding Register  inside  of  the  8250  is
empty.   If  it  isn't,  PC-VT  goes  into  a  loop waiting for an interrupt
signaling the emptying of that register and completion of  the  transmission
of the previous character.  If the 8259 misses the interrupt, PC-VT is never
awakened.   So the older versions of PC-VT would just hang.  This version of
PC-VT uses a time out and awakens itself if  the  interrupt  handoff  fails.
Then,  PC-VT  must  reset  the  8250 to get things back to normal and try to
resend the character.  Eventually, it is successful.  The bad part  is  that
if the receive buffer in the 8250 had a character from the line, it would be
lost.  National Semiconductor tells me that the chip you need for successful
interface  to  the 8259 in the IBM PC is the plain 8250 or the 8250B version
of the IC.  The 8250A version will not work correctly.  Understand that this
is not a malfunction of the 8250, its just that IBM designed into the PC  an
actual  mode of operation of the 8250 which was not in the specification.  I
have  implemented  a  fix  for  this  problem  as  suggested   by   National
Semiconductor.  It has been tested on a serial board with the 8250A chip and
it  works.  If you continue to have problems, I suggest that you contact the
dealer who sold you the serial board.

	Note  to  UNIX  users: most UNIX hosts send garbage or parity as the
8th bit if you are transmitting at 8 data bits.  PC-VT tries to get  rid  of
these  bits  before  it processes the byte.  There are cases ( especially in
the  older  versions  of  PC-VT)  that  still  cause  problems.   Set   your
transmission  protocol  up  at  7 data bits if you don't need the 8th.  This
version of PC-VT will let you run at 7 data bits for  normal  operation  and
will  switch  automatically  to  8  data bits, 1 stop bit, and No parity for
XMODEM transfers.  Also, the ALT = key combination will send  an  ASCII  127
which  is  a  rubout to UNIX.  The backspace key also sends a rubout, but if
you have redefined the backspace to a CTRL-H, you can still  send  a  rubout
with the ALT =.

	With  this version of PC-VT, I have made the program more compatible
with Computer Conversations' "Enhanced PC Talking Program" for the  visually
impaired.   Specifically,  the Alt-Function keys which can be used as macros
in PC-VT, will not interfere with the Talking Program if they are  not  used
as  macros.   The Alt-1 to Alt-dash keys are no longer used by PC-VT.  Their
functions were moved to other Alt keys.  The Alt= key,  which  in  PC-VT  is
used  to send a Delete (ASCII 127), is the only key which both programs use.
For more information on the  Talking  Program,  contact  Ron  Hutchinson  at
Computer   Conversations,   2350  North  4th  Street,  Columbus,  OH  43202,
614-263-4324.

	Both  the  .EXE  module  and  source  for  PC-VT  are  available for
commercial  distribution.   Contact  me  for  details   of   the   licensing
arrangements and fees.

	Also  included  is a line printer redirection program which I wrote.
It is in the library file LPTXxxx.LQR.

	Since  this  program  is  user  supported,  it  is  user  driven.  I
continually make upgrades based on user requests.  Since my  version  number
would  be  4853.3434543  if  I  changed  the  version number with each minor
update, I bump the version number only when a significant change occurs.   I
will use this file to list the upgrades within each version number release:

DATE	Function:		Change:
----	---------		-------
1/23/85	ALT Function Keys	I changed the meaning of several of
				the ALT keys so as to be more
				compatible with Computer Conversations'
				"Talker Program:.

1/24/85	Transmit ASCII file	If the host sends a CTRL-Z to PC-VT
				while PC-VT is uploading an ASCII file,
				PC-VT will cancel the upload.

	I  hope  that  the program is of use to you.  I would appreciate any
comments which you might have regarding the program or its usefulness.  When
you write, please indicate the version number of PC-VT which you are using.

Sincerely,
Mark C. DiVecchio
9067 Hillery Drive
San Diego, CA 92126
619-566-6810
