Mike's PCjr Page

Has anyone used the PCjr 4863 as an EGA display? On paper it seems like it should work for the 200-line EGA modes at least, assuming you constructed a DE9 adapter.

There's a decent alternative to HxC called Flash Floppy . It's free and seems to work well for me on the PCjr. Granted I haven't tested it extensively but I'm pretty happy with it so far. I flashed a (different) Gotek with FlashFloppy (2.14) today and so far it has none of the issues I've had with ...

The only thing that stands out is that the RASB signal (pin 4) is not continuous between banks though CASB (pin 15) is. I'm not sure if this is supposed to be so and I can't see evidence for either case from traces on the crowded board. I've traced the RASB signal for both banks to the PLA at U23. ...

I've been having better luck after throwing out all my image files and starting over with only HFE files that I produce myself. Meaning no "off the shelf" IMG files go on the Gotek, as I cannot get those to work properly. Even so, booting to an HFE disk image is pretty hit and miss; someti...

This has been an interesting thread. I have used this "turn on the sound chip" project as my Hello World in x86 assembly. section .text org 0x100 in AL, 0x61 ;read port to AL xor AL, 0x60 ;toggle bits 5,6 out 0x61, AL ;write AL to port int 0x20 ;terminate Every time you execute, the sound ...

DarkStar2032 wrote:Do you have specs on that AC adapter?

It’s a 9 VAC adapter but you can use any 9-12 VDC adapter since the input is immediately rectified and sent through a 5VDC regulator.

Fully loaded the jrCaptain manual says it wants 780ma.

Hello PCjr enthusiasts. I am a Kansas City retrocomputing hobbyist who recently acquired a PCjr from a fortuitous Facebook Marketplace find. It's a quirky machine but might be fun. I am mostly concerned with Apple II computers since that's what I grew up on; we got a PC-clone in 1989 or 1990, a 386s...

I must be doing something wrong, but I can't tell what it is. I have a Gotek flashed with HxC. It only works on the "B" ribbon position (pre-twist); but then "works" is an open question, since I can only boot 180K disk images (e.g., PC DOS 2.1) and cannot reliably read 360K image...

I recently got a PCjr with a jrCaptain sidecar. The only thing good about it is that it was upgraded to 512k, but it doesn't work. 1. The AC transformer and barrel jack were both broken. I replaced the jack and removed the rectifier circuit so I could use a DC transformer. 2. The voltage regulator a...

No faults from boot or user diagnostic test. It's like it's not even there. If I'm following you correctly it seems to be an address decoding fail. Correct? In troubleshooting my jrCaptain, I've found that "not even there" means it's not plugged in. My sidecar came with a busted AC transf...