Mike's PCjr Page

Hi.

I recently acquired the IBM compact thermal serial printer. The printer passes the self-test as well as the test through the PCjr internal tests as outlined in the Guide to Operations. However, using LPRINT under Basic gives a timeout error. Is Basic expecting a parallel printer, and if it is, how do I make it see the serial printer? I would like to use the Compact Printer for Basic listings.

Walid

I haven't played with the compact printer in a while, but if you have a parallel port the BIOS is probably getting things confused. Without a parallel port the BIOS will setup LPT1 to point to the compact printer, which is on the serial port. With the parallel port it probably doesn't do that.

You can use the DOS mode command to point LPT1 at the serial port. I think the compact printer runs at 1200bps.


Mike

Wouldn't that affect up my external zip drive then? The drive is connected to LPT1 and the Xircom adapter to LPT2. I suppose I could access the printer from Basic using the OPEN command and access the COM port directly, but I would not be able to list programs that way. Interestingly, the computer did see the printer on the serial port during the tests...

Walid

Well, it actually worked! Using the DOS MODE command and setting up COM1 to 12,8,N,1,P and then redirecting LPT1 to COM1, I was able to use the printer as LPT1 without difficulty and I apparently still retained full access to the parallel zip drive connected to LPT1. So I went ahead and incorporated these commands into my autoexec.bat file.
Thanks for the tip

Walid

It works because the Zip drive is going to figure out that LPT1 is the first printer port listed in the BIOS area, and it is going to ignore anything DOS does. It is going to manipulate the port directly by hardware address, and will probably never use the "LPT1" device as DOS sees it.

When you use the MODE command to redirect LPT1 DOS and BIOS change the code that print the bytes. However, the address of the printer port is still there and unchanged, so the Zip drive can use it just fine.

Makes sense. I am glad I can use that printer because it is relatively quiet and has such a small footprint. For listings and such, it does the job beautifully.

Walid

Do you have a good supplier for the paper? Thermal paper is not exactly common. (I haven't looked recently though.)

Not really. I have an old box of standard thermal fax paper rolls that work just fine (my old fax machine is long gone...). Unfortunately, the rolls are too thick to allow the complete closure of the cover (the width is fine) and too heavy for the friction pull, so I simply unroll a couple of feet or more if needed and thread them through. One roll is nearly equivalent to half a box of perf paper at least. I looked around a bit on the internet for a supplier, but did see any. If you happen to come across one, please let me know.

Walid