UPL100 Model 100 Upload Utility
                 for the TRS-80 Model I/III

Version 1.0
Aug  1 83
Copyright (c) 1983 Morris Jones
Permission  granted to copy for non-commercial use  provided 
credit is given to the original author.   No changes may  be 
made to this document without permission from the author.

     UPL100 supports continuous stream file uploads from any 
terminal  that  supports XON/XOFF  handshaking,  i.e.,  will 
pause  the data transmission when the host sends XOFF (ASCII 
X'13') and resume when the host sends XON (ASCII X'11').  No 
checksums or other verification is provided by this protocol.

     UPL100  is provided in source form for EDTASM,  and  is 
independent of DOS used.

Features:

o    Aborts  after two minutes without receiving  data  from 
     the remote.
o    Aborts on loss of carrier.
o    Local  filename  to receive the upload is specified  on 
     the command line.
o    Uses  memory from 5200H to 6FFFH to allow running  from 
     within a BASIC program (under Newdos/80).
o    Remote operator ends the upload by pressing control-D.
o    System  operator  can abort the upload by pressing  the 
     BREAK key.
o    Supports 300 or 1200 baud transfers with no lost data.
o    Allows for slow reaction time by the remote on an  XOFF 
     by sending 10 NULL characters after an XOFF.  Up to ten 
     additional  bytes  of data may be received  before  the 
     remote must stop sending.
o    Timeout  is  measured by checking the real  time  clock 
     instead of a count loop.
o    Simple  changes  to the source to modify any  of  these 
     features.

     UPL100  was  written to be used from a  bulletin  board 
system  for  uploading  files from  the  TRS-80  Model  100, 
although  the  method is applicable to many other  terminals 
and terminal emulation programs.

     Under  Newdos/80,   for  example,  UPL100  may  be  run 
directly from within BASIC.  For example:

LINEINPUT"Type the filename you with to upload: ";FN$
CMD"UPL100 "+FN$

This  will execute UPL100 and return to BASIC  execution  at 
the line following the CMD statement.

     The  remote operator (and the system operator) receives 
the message:

     UPL100 by Morris Jones
     Version 1.0 Aug  1 83

     Ready for Upload --
     Press control-D when finished

The  remote then begins sending data to the host.   Data  is 
buffered  until an almost full buffer  condition,  when  the 
host  sends XOFF and ten NULL characters,  allowing time for 
the  remote to stop sending.   The buffer is written to  the 
disk file,  reinitialized, and an XOFF is sent to the remote 
to indicate that it may resume transmission.

     At the conclusion of the data transmission,  the remote 
operator  should  press control-D.   UPL100 then  sends  the 
message:
     One moment . . .
followed by
     File Upload Complete

     During  the data transmission the received data is  not 
echoed to the remote.

*** Important Note ***
     Message  strings sent by UPL100 are duplicated  to  the 
serial port and to the console (video screen) of the TRS-80, 
so if the video DCB has been redirected to send video output 
to the serial port, the remote operator will see each letter 
twice:
     UUPPLL110000  bbyy  MMoorriissss  JJoonneess
Video  redirection should be disabled before UPL100 is  run, 
or  the source should be modified at routine SERSTR so  that 
string  data  is  not  duplicated to both  serial  port  and 
console.

Error conditions:
     A  lost  carrier will cause UPL100 to abort  without  a 
message.
     Timeout  occurs if no data is received from the  remote 
for two minutes.
     A file write error causes UPL100 to abort.  With no way 
for  UPL100  to instruct the remote that the upload must  be 
aborted, it is likely that considerable garbage data will be 
received from the remote after UPL100 has aborted.

Error messages:
     ABORT -- No File Specified
     ABORT -- Disk File Error
     ABORT -- Timeout

.pa
     Please send all modifications, suggestions, and correc-
tions to this program to:
     Morris Jones
     PO Box 641
     Forest Knolls, CA  94933
     Bulletin board: (415) 488-9145