Tincanalley wrote on 2021-08-23, 23:54:

So if it is an AMD, is that a good thing, or bad? Also, if you look above it there is a socket with another socket plugged into it and 2 resistors. Is that were a math co-processor would go? If not, where does one plug one in?

AMD was a 'second source' for Intel processors in the 286 era. They are functionally the same. AMD did make faster versions though. I think that is the spot for the co-processor, no idea why there is a resistor in it.

Tincanalley wrote on 2021-08-23, 23:54:

I'm also assuming the chips that stickers "PH3.XXX" are the BIOS chips? I tried searching for them, but came up empty.

Yes i think so. I tried searching in UH19 for this board (link below in sig) but we don't have it, so can't help with the jumper settings. I can tell you it has the C&T CS8220 PC/AT compatible CHIPSet, details:

http://66.113.161.23/~mR_Slug/chipset/chipset … 455&3=4533#2043

This is one of the very first chipsets so has some limitations. But you have a fast motherboard for '85-86.

Please can we use your picture in the UH19 DB?

mR_Slug wrote on 2021-09-12, 19:17:

AMD was a 'second source' for Intel processors in the 286 era. They are functionally the same. AMD did make faster versions thou […]
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Tincanalley wrote on 2021-08-23, 23:54:

So if it is an AMD, is that a good thing, or bad? Also, if you look above it there is a socket with another socket plugged into it and 2 resistors. Is that were a math co-processor would go? If not, where does one plug one in?

AMD was a 'second source' for Intel processors in the 286 era. They are functionally the same. AMD did make faster versions though. I think that is the spot for the co-processor, no idea why there is a resistor in it.

Tincanalley wrote on 2021-08-23, 23:54:

I'm also assuming the chips that stickers "PH3.XXX" are the BIOS chips? I tried searching for them, but came up empty.

Yes i think so. I tried searching in UH19 for this board (link below in sig) but we don't have it, so can't help with the jumper settings. I can tell you it has the C&T CS8220 PC/AT compatible CHIPSet, details:

http://66.113.161.23/~mR_Slug/chipset/chipset … 455&3=4533#2043

This is one of the very first chipsets so has some limitations. But you have a fast motherboard for '85-86.

Please can we use your picture in the UH19 DB?

Absolutely. Use any pics you like. I managed to get the board working. It is a Phoenix BIOS and I found the ATSETUP worked like a charm. The last, and final issue, was the speed. I set the BIOS to high speed, but it ran at AT speed, not 10Mhz. I spend days on the issue and almost gave up. The case doesn't have a turbo switch, but it does have a turbo LED. I tried every keyboard combination to enable turbo mode, but the only thing that did was find me a key combination that added ticks to my keystrokes from the speaker. Turned that off as it was so annoying.

Just before I was about to toss the board into the closet, I went over it one more time. I looked at the header pins and next to the turbo LED connections there was a pin with "SC" on it and a "G" pin next to that. So I sat and wondered what it could be. I searched the internet and found nothing. Then I started running words that the SC could stand for. Then I thought about "Speed Control" and I figured it wouldn't hurt to jumper them. When I did, it jumped up to 10 and the turbo light went on. So there must have been a jumper in the past and it was removed.

Anyway, the board is fully functional now and all ready for use.

Indeed a very nice early board!
Having the expensive 8742 instead of a cheap 8042 makes me guess it might even be some prototype.

BTW, I'd take a backup of the ROM of the 8742 controller, as the window is only partially covered and data loss might be imminent.

retardware wrote on 2021-11-02, 21:13:

Indeed a very nice early board!
Having the expensive 8742 instead of a cheap 8042 makes me guess it might even be some prototype.

BTW, I'd take a backup of the ROM of the 8742 controller, as the window is only partially covered and data loss might be imminent.

So the ROM is in danger from the window being exposed? If so, what is the least expensive way to back it up? I don't see me doing it often, so buying an expensive one doesn't seem wise.

Crazy! I had no idea the ROMs with a window were erased with UV light. Learn something new everyday.

"8742 Erasure Characteristics
The erasure characteristics of the 8742 are such
that erasure begins to occur when exposed to light
with wavelengths shorter than approximately 4000
Angstroms () It should be noted that sunlight and
certain types of fluorescent lamps have wavelengths
in the 3000-4000 range Data shows that constant
exposure to room level fluorescent lighting could
erase the typical 8742 in approximately 3 years
while it would take approximately one week to cause
erasure when exposed to direct sunlight If the 8742
is to be exposed to these types of lighting conditions
for extended periods of time opaque labels are
available from Intel which should be placed over the
8742 window to prevent unintentional erasure
The recommended erasure procedure for the 8742
is exposure to shortwave ultraviolet light which has a
wavelength of 2537 The integrated dose (ie UV
intensity c exposure time) for erasure should be a
minimum of 15 w-seccm2 The erasure time with
this dosage is approximately 15 to 20 minutes using
an ultraviolet lamp with a 12000 mWcm2 power rating The 8742 should be placed within one inch of
the lamp tubes during erasure Some lamps have a
filter on their tubes which should be removed before
erasure."

Data retention is usually guaranteed for 20 years only, and this is with the window completely obscured.
On a windowsill, an EPROM can be erased in just three weeks.

I am no 8742 expert... you might want to check whether a generic keyboard controller works; in this case it won't be a big problem if the 8742 finally stops working due to bit rot.
Maybe it might easily backupable by TL866, haven't tried that myself yet because I don't have one of these expensive 8742.

Personally, I find old 5.25" diskette write protect stickers very convenient to make sure my EPROMs aren't exposed to light.

I will for sure put one of the write protection stickers on it. I have no clue how long it has been exposed to light. It was in a case when I got it, so if that is the original case, it hasn't been exposed to much light.