1/30/84 T. J. McGinty INSTRUCTIONS FOR USING THE PRINT-20 DRIVER WITH THE AUTOPRINT MODEM The AutoPrint Microconnection has provision for connecting a Centronics compatible parallel printer. The following program allows the printer busy line to "handshake" the VIC-20. This will prevent printer overruns and dropped characters. To use the program, follow this procedure. 1. Load the program. 2. RUN the program. As the program runs it pokes a Machine Language routine into the top of RAM for an unexpanded VIC. It then protects itself from BASIC by lowering the top of memory pointers. 3. Type NEW, then load the program you want to list on the printer. 4. Type the following line in direct mode: POKE 781,X:SYS 7392:LIST X=tha code for baud rate according to the following table: Baud Rate Table 0=110 1=150 2=300 3=600 4=1200 5=2400 6=4800 7=9600 Your program will be listed on the printer. If you are dumping a printout through the Autoprint Modem, be sure the right-hand switch is in the OUT (VOICE) position. You should select 1200 baud (4) in this case. If no baud rate is poked into 781, or if the number poked is not in the range shown in the table, the program will default to 110 baud. To deactivate the print routine, type SYS7457. Once activated, the routine will send all screen output to the printer. The program may be activated and deactivated from within a BASIC program by using the same POKE and SYS commands. As written, "Print 20" looks for the printer's handshake (BUSY) line to go low before allowing printing to take place. If you need to change the polarity of this line to be compatible with your printer, it is only necessary to change two elements in line 390. In line 390, the sixth element is B0., and the ninth element is 90. Swap these entries, so the 6th element is 90 and the 9th is B0. Then RUN the program. Printout will now take place when the BUSY line is high and will not print when the BUSY line is low. This program has been provided by The Microperipheral Corp. and is in the public domain.
Amiga7878