Mike's PCjr Page

I've got this installed and I get video snow using the 8284 Chuckphd sent + the PCjr 8284. Others have mentioned that both chips need to be 8284A1s to operate in full speed without issues, so is this possibly the case here? I'm using my own board design based on the original D. Severson schematic, ...

Has anyone tried NoBeep in DOS 5? The executable writes gibberish to the screen and the device driver hangs the machine. This is on a jrIDE with jrconfig 3. Yep, that's the same behavior I see, although other than the gibberish, the TSR does work fine and does what it's intended to, as far as I can...

The goal of these speedups for the PCjr is not necessarily to bridge over into a new class of software you can run, but rather to make existing 8088/PCjr-class software pleasant to use. With a topbench score of 8, you could look at it as 20% slower than a 6 MHz 80286, but I prefer to look at it as ...

It seemed implausible that nobody had done this already, but I couldn't find any evidence online, so . . . I patched the Prince of Persia 1.3 executable to bypass the tandy bios verifications, and TGA graphics mode now works fine on a tandy-modded Jr. Music is another matter - I've again bypassed th...

Assuming one could gather a sufficient number of external power bricks still in working order to service the necessary power sidecars, would such an abomination actually function? The sidecar connectors must produce some voltage drop . . .

Yeah, Trixter pointed this out earlier in this thread (and I confirmed myself despite the obvious credibility of the source :) ) - if you write to, and then read from (repeatedly and immediately following the write) port 201, you can see that bits 2 and 3 will be on for a variable duration (accordin...

I can confirm this. The offset increases (towards the lower right) with increasing CPU speed. Here's an image with a V20 at 9MHz (after centering at 4.77MHz). The trim levers don't have quite enough range to get it centered at 9MHz, but I haven't had any trouble using it in actual software (I played...

I poked at lemmings a bit today. You can obtain different behavior when running tgalemmi.exe by changing the amount of video memory reserved by jrconfig.sys, and/or booting without jrconfig at all. The latter results in the closest thing to a running state I can achieve - after the initial "ple...

So, this would be funny if it weren't so dumb, but I finally found the problem, and it was that I literally had a screw loose :| there was a case screw loose underneath the motherboard, making intermittent contact with something. I apologize to anyone who wasted seconds or minutes of their lives rea...

Many thanks for JOYCALIB, extremely helpful. So, joycalib works successfully (ie. detection, ranging, and then the final screen for trimming all work normally) with a joystick in port B (regardless of processor speed). With the joystick in port A, a joystick is detected, but after setting upper-left...