Mike's PCjr Page

I have a functioning 128k PcJr, with 128k of ram, no monitor so using composite output, and no expansion cards.
What kind of goodies should I get for it? I would like to get more ram and perhaps an IDE interface. Anyone have either of the above for sale? I have a 3D printer so I should be able to print a case. Any assistance would be great.

I’ve seen posts about the jrIDE, that sounds promising. A kit of parts would be cool. I think it should also help in the ram department. I’m good with a soldering iron and have built many computers from kits, including an OSI 600 Rev.D.board with 80 chips, along with a few S100 cards. So I can solder and mod.

Speaking of mods, I’ve read up on the Tandy video mod, but have yet to find the post that describes how to implement it.

Cheers everyone!

Welcome to the club ...

Your first upgrade should be a real monitor. The composite output is good enough for games and 80 column text with the colorburst signal turned off, but 80 column text in color or complex graphics are going to look nasty. The official PCjr monitor works well enough but the dot pitch is pretty crude. There is a thread here on VGA conversion kits so you can use a VGA monitor with the RGB TTL output on the machine.

The next upgrade is RAM. 128K is good enough for BASIC programming and cartridge games. Real DOS applications will be much happy with 384K or more. And if you think you might want to add a hard drive, then just get the jrIDE - it adds the RAM and the hard drive interface in one sidecar. It's changed the way I use my system.

Before I had a jrIDE I had SCSI drives connected via the parallel port. Ye olde 100MB parallel port Zip drives also make reasonable stand-ins for hard drives, but you have to boot from a floppy with those and the data transfer rate is pretty low.

Lastly, I'm a big fan of networking. Find a Xircom PE3-10BT and go online with the beast ...

Cool thanks for your reply, I’ve sent a note to AlanH about the jrIDE, hoping for a response.
I did purchase the CGA and serial port adapter board as well as the joystick and keyboard
Adapter board as well. I got a confirmation email, but have not heard back since, but it’s a
super long weekend in the US that might be why.

I do have a question regarding basic and composite output. When I turn the pcjr on, I get the the
Color display and memory test, and then into basic as I don’t have a boot floppy. In basic, if I use the color statement,
Say, color 4,3. The result is gray scale, even though the initial pcjr boot up screen and memory test was color.
Do I have to turn on color mode first?

Thanks in advance.

I think it's your monitor/TV getting confused.

Composite video is fascinating. Originally it was just black and white. With the introduction of color the signal was altered and the engineers managed to shoe-horn the color encodings into the signal without affecting the ability of black and white receivers to use the signal. They did this by introducing a colorburst signal at the beginning of the scan-line to sync the color receivers, and then used phase-changes in the signal to indicate which colors needed to be drawn and at what intensity. A normal black-and-white receiver doesn't see the colorburst signal and doesn't give a crap about the phase changes, so it just works.

Modern devices *should* support this correctly but many don't. I've had an LCD panel here recently that could not display a black and white signal from the PCjr, but it worked fine in color.

On the PCjr you can enable or disable color (the colorburst signal) by using the mode command in DOS or the SCREEN command in basic. Look up the reference but the SCREEN command allows you to set color vs. black-and-white, which is just controlling the colorburst signal. If your monitor/TV got confused when you went to BASIC then running the SCREEN command again might fix it.

Screen command worked great, thank you

Happy to report, i managed to order a Jr-IDE interface from Alan.
very very happy, Thanks Alan.