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I just got another Model 1 (the other one I have has an intermittent fault when pushing on the circuit board, but no matter how much reflowing I've done, I haven't been able to locate it). This one has an interesting video issue. See link to the YouTube video. I would guess it's one of the...

Based on a very old thread on this forum and some other threads I found online, I thought it might be fun to try to get an old XT going with a ISA USB board based on the CH375 IC. I found one on Taobao in China and managed to wrestle through the Google Translator to actually make the purchase...

Hi All, I had a nice working 20MB MFM disk in one of my XTs, working off an 8-bit MFM controller (WD). I decided it would be fun to try to see if the drive would format to 30MB on an RLL controller (I remember doing that years ago, and as long as the drive is of sufficient quality, it works...

I spent most of the morning today tinkering around with the PPC-21 I have here to see if I can somehow make it emulate CGA like its bigger brother, the CorData (P)PC-400. First try was to swap out the BIOS. The PPC-21 runs 3.10, and the PPC-400 has 4.23/4.33 (at least, those images I have...

Keyboard was repaired with new foil. HDD had failed, so disconnected it, and put in a XT-IDE with CF card. Next is trying to run the newer PPC-400 BIOS (16K instead of 8K) on it when I get an ISA ROM board, and add an Intel Ethernet board to tie it to my IPX network for easy file sharing.

Does anyone know what this is? And can point me to dip settings? This came from a Corona PC-400 and appears to fill the gap from 8000H to AFFFH (yielding 704K memory on bootup). No brand name, and no part number on the board. And only 8 out of the 18 IC slots filled....

I just dumped the BIOS (2764 EPROM) from a Corona PPC-21 portable machine. It's revision 3.10. modem7 -- maybe a good addition for the minuszerodegrees site?

Hi Everyone! I had a friend donate an old PS/2 Model 80, which had some MCA network boards in it (a 3270 emulator and Token Ring board). I would like to hook it up to my "vintage computer network", but needed an Ethernet board. Without doing a ton of research, I found an IBM 00G3368 bus master...

Hi guys, I have two of these laptops and one is behaving nicely, while the other one keeps thinking there is some kind of memory size problem. The one with the memory size problem has the standard 2MB on board and a 4MB 72-pin SIMM stick. The memory size error shows up with or without the...

I bought a 2MB Micron memory expansion board off eBay. Micron PN 235-0149. I plugged it in one of my machines, and it works. Seems to fill in address space from 1M to 3M. I have a similar board which is defective (235-0140), which has dip switches. This board appears to have a ROM and no dip...

I was just reading a bit in the XT-IDE 2.0 BIOS thread, where there was an announcement that the new version can boot through a serial port. Very interesting option to run diskless systems, but that got me wondering about network boot... I know that used to be a thing with Novell boot roms etc...

Hi All, I have this 2MB 16-bit ISA board, Micron, (extended memory) that has at least one bad IC on it. When I run the Checkit memory test, the test fails in one 256K segment (the second on the board), and claims it's all parity, C. Looking at the board, it looks like the IC's are arranged in...

I have a nice 5150 system, 16-64k mainboard, original power supply, original 10MB HDD (with only 1 bad sector!). The system is beautiful minus the constant squeak from the 10MB HDD. It sounds as though it could come from one of two locations and I haven't been able to "put my finger" on it. I'm...

Hi All, An old PC I bought off eBay a while back had a SCSI 1GB Jaz and Zip drive in it. I recently bought some media for it and got the Zip drive working no problem. But the Jaz drive won't spin up. When inserting the cartridge, you can hear the insertion mechanism whirr for a short time, and...

Hi All, I've had this nice old CRT monitor for a while, but it's always had a funny color gradient and slight bending of the image on the top right corner of the screen. I'm pretty sure someone has had some fun with magnets with this thing in the past. It has a degaussing function on the menu...

Hi All, I've started working on an old 5151 monochrome monitor that worked for a little while once I got it. I left it on for 30 mins, walked away and came back to a nice burnt electronics smell... I started diagnosing and replacing components. First thing that was broken was the main 22V...

Hi All, I picked up a 5150 (16-64kb mainboard) from eBay in a non-working state (as in, dead) and kind of hobbying around trying to get it to come back to life. Turns out the power supply was bad (really bad, as in a blown fuse.. Replacing the fuse got a puff of smoke and a fried NTC.. Not...

I have had an old ST251-01 sitting on a shelf for a while, but didn't have a controller to drive it. Today I picked up an old IMB 5150, which had a WD1002S-WX2 controller in it, but no HDD. So I put 1+1 together, so to speak, and tried to low level format the drive. The first try succeeded...

Hi all, I just got this Lung Hwa VGA board for my 286 system off eBay. Works fine, but curious about the function of the jumper on the board and the 4 dips on the bracket side of the card. And if someone ever made a VESA driver for this guy. Thanks!

Hi Everyone, I have a Princeton HX-12 CGA monitor that's exhibited a weird problem ever since I got it a few years back. It would not display one of the CGA colors until it's warmed up for about 30 mins after which it suddenly works fine. So when it starts up, the text on the screen is magenta...