Documentation for the file JRPTR.100
by Bob Scott 73125,1437 (AUG 88)

Recently IBM PCjr thermal printers have appeared on the surplus market for as 
little as $29.  This program acts as driver for the PCjr printer, allowing the 
M100 to dump files to it at the fastest possible speed without data loss.

Out of the box, the printer has an odd-ball connector (yet another reason for 
the PCjr's sucess, no doubt) which you must replace with a standard male DB-25 
connector available from Radio Shack.  Referring to the pin-out on page 37 of 
the printer manual, connect the wires as follows:

  Printer -> DB-25
  Ground (B04/B07)(black) (2 wires) -> pin 7
  Clear to Send (A07)(white) -> pin 5
  Trans. Data (A04)(red) -> pin 3

The colors above were correct for my printer, but you should check the actual 
pin connections on yours to be sure.

After making the connector, connect the printer to the RS-232 port on the M-100
and run JRPTR.BA; it will present you with a list of files.  Type in the name
of the file you want to print and press return.  After printing the file, the 
program will return to the main menu.  If you want to abort the printing 
process, press SHIFT-BREAK or type CTRL-C.

The PRINT statements at the top of the program set the "form length" to two 
lines.  This is handy if you dump a captured file from CIS to the printer; most
CIS downloads have one or more form feeds in them (^L) and this translates them
to a simple double space instead of wasting a page of paper.

Line 50 is the key to this program. The INP(187) picks up a PIO input byte, and
ANDing this with 16 masks off bit 4.  This bit gives the status of pin 5 of the
RS-232 connector.  If INP(187) AND 16 = 0 then pin 5 (CTS) is high.  If the 
result is 16, then CTS is low (this usually means the connected device cannot 
accept data).  In this case the program simply loops until CTS tests clear.

If you want to check the status of pin 6 (DTR) substitute INP(187) AND 32. This
works similarly, but the values to test for are 0 or 32 to indicate DTR high or
low.

By changing the STAT parameters in the OPEN statement above, and selecting the
correct pin to test, this little driver program should work for almost any 
hardware handshaking serial printer.