Mike's PCjr Page

Happy new year PCjr Guru's!

I recently received an IBM Compact Thermal Printer for my PCjr. It seems to work as far as holding the line feed button down during power up causes it to print a test pattern, however when I try to print from IBM Writing Assistant, Print Shop, or even the Typewriter software on the PCjr Sampler disk nothing happens. I imagine it is sending the printer data to the LPT port which isn't even installed? Historically I had the parallel port sidecar installed and a dot matrix printer plugged into that which worked fine.

Any ideas on how to get Writing Assistant, Print Shop, or really anything else to connect to this serial printer? Sorry if this is a totally newb question but I've never owned or used a serial printer before.

The issue may be the serial port addressing. Without an internal modem installed, it is port 1. With it installed, it is port 2. Try setting different serial ports in the software you are using and see if one of them works.

I looked around on this site and found this setting for it. Com1,1200,8,n,1

I hope that helps. You can search for thermal printer to find posts about it. Mike has one and may be able to help you.

I think the trick is to turn the printer on first before the computer.

The BIOS of the machine will try to detect that the Compact Printer is connected. If it does detect it then the BIOS will magically re-route LPT1: to the serial port. This of course assumes that the program is well behaved and is using BIOS routines to do printing, not bit-banging the parallel port directly.

If the printer is not turned on or connected before the machine powers up the magic redirection does not happen. Then you have to tell programs that you have a serial printer on COM1 running at 1200 bps.

Brutman wrote:I think the trick is to turn the printer on first before the computer.

The BIOS of the machine will try to detect that the Compact Printer is connected. If it does detect it then the BIOS will magically re-route LPT1: to the serial port. This of course assumes that the program is well behaved and is using BIOS routines to do printing, not bit-banging the parallel port directly.

If the printer is not turned on or connected before the machine powers up the magic redirection does not happen. Then you have to tell programs that you have a serial printer on COM1 running at 1200 bps.

I see. I have a an Racore 5.25 floppy/memory expansion and I know that it adds to the BIOS for the 2nd drive support. Could that interfere with the magical re-routing? I'm pretty sure the printer was powered on first but possibly not. I also typically use a PC Enterprises combo cartridge v3.0 which also adds to the BIOS too, I think. I tried with and without that, though.

Writing Assistant should be well behaved in that respect. The PC Compact Printer is referenced in the literature after all. I thought for sure the typewriter program on the sampler disk would work. Both indicated "successfully sent to printer" or something along those lines but nothing happening at the printer. Print shop gave an error message along the lines of "Check your printer". I'll have to try it again paying special attention to what gets turned on first and maybe try it without the expansion chassis. Gotta be on a different day though. It's all packed up for now plus I have to get more thermal paper on order.

Thanks for the feedback. I'll post an update when I mess around with it more.

In DOS, you can also try the commands:

MODE COM1:1200,N,8,1
MODE LPT1:=COM1:

(adjust COM1 to COM2 as mentioned if needed)