Continuing to work on the 486 motherboard from above posts... Soldered a VRM (I went with a LM338) and confirmed with voltmeter that it gives out the correct voltage... 3.41V, perfect. Soldered a few missing jumper headers, and also a coin cell holder which the MB had a solder print for but they went foolishly with the NiCd battery instead which leaked... won't happen again. 😀
Tested the new and inproved motherboard with some higher end CPUs.
First was a Intel Overdrive DX4ODPR100. The computer would not boot with it. Checked everything again including voltages and jumpers, all is good. TBH I had never used this overdrive, it may be dead.
Second an AND 5x86-PR75. Booted right up, recognized as a DX4-S
![20181019-111105-AMD-5x86-PR75.jpg](https://i.postimg.cc/28SFJC1f/20181019-111105-AMD-5x86-PR75.jpg)
Next up, Cyrix 5x86-100GP. Lots of jumpers to change for this one.
It boots but only as 66MHz, and recognized as a 80487SX. 😀 Probably have to fiddle with jumpers more.
![20181019-111424-Cyrix-5x86-100-GP.jpg](https://i.postimg.cc/LXrBwbbF/20181019-111424-Cyrix-5x86-100-GP.jpg)
![20181019-111433-Cyrix-5x86-100-GP.jpg](https://i.postimg.cc/qqsbLrM5/20181019-111433-Cyrix-5x86-100-GP.jpg)
Tried to take a picture of the VRM but the phone decided that it should be out of focus. It's a LM338. Also don't worry about the lack of HSF on the CPU, I powered it on only for a few seconds to take pictures. It got barely warm. Eventually I'll put heatsinks both on the CPU and on the VRM.
![20181019-111604.jpg](https://i.postimg.cc/G3KmMy8q/20181019-111604.jpg)
(edit) it was pointed out to me that the overdrive is a 5V CPU, which I had forgotten. Will test again at 5V. 😀
I/O, I/O,
It's off to disk I go,
With a bit and a byte
And a read and a write,
I/O, I/O