Mike's PCjr Page

I cannot explain what's happening, but what you mentioned about not inserting an extra wait state sounds plausible.

A while ago a did some performance tests on my PCjrs and noticed that one PCjr was a tiny bit faster than the others. Being new to the PCjr world, I never imagined that a daughter-board could be installed under the floppy drive. And I knew I didn't have a NEC20. Today I decided to fix a few issues i...

+1 Agreed with Brutman comments. I would add this PSU has more power than the original one (specs here: https://www.retrotronics.org/home-page/jrpsu/ ). Ideal if you have external floppy drives + extensions (like in my case). jrPSU photo (while I was repairing my floppy drive and discovered a Hotsho...

welcome and nice setup!

Thanks. Good to know!

Trixter wrote:CGA -> splitter cable (so I can hook up a monitor) -> gglabs CGA2RGB -> VGA gender changer -> VGA cable -> VGA to DVI adapter -> Epiphan DVI2PCIe with CGA video defined as a custom VGA mode.

Thanks

Trixter wrote:The RGBI -> analog RGB portion of my capture chain broke. Exploring replacements. Sorry, this might be another week or two.

Thanks!

Would you mind sharing what devices are you using for the capture? I want to have my own chain as well... Thanks.

I'm paraphrasing from the tech ref, but the VGA chip accesses both 64k banks in parallel to enable the high bandwidth needed for 320x200x16. Ahhhhhh... From Tech ref: The system board 64K RAM is mapped at the bottom of the 1Mb address space. The system board 64K RAM is mapped to the next 64K bytes ...

This is a wonderful demo and an even more wonderful technical write-up. I'm very pleased! You even managed to squeeze in 640x200x4. Thanks. 320x200x16 doesn't work in a 64K PCjr because there isn't enough memory bandwidth. Do you know why is this happening? Since the demo, even with 128KRAM, never ...

Hi, We (PVM) have just released a demo for the PCjr (works even on the 64K-RAM only version[*]): video: https://www.youtube.com/watch?v=uakDpJns9LA (thanks monzamess for the capture). Binary download: http://pungas.space/pvm-64ko.zip (only run on real hardware, no emulators) source code here: https:...