pentiumspeed wrote on 2020-05-15, 01:38:

Lucked into memory expansion card 32bit with correct speed rating memory (80ns) instead of 100ns for my Compaq 386/25e, made by kingston and is either 1MB or 4MB 32bit parity card with 2 spots for compaq plug in style 1 or 4mb modules. Hope that is compatible with mine, was not expensive. Not described well enough but was lucky to keep exploring their seller's websites.

If works, I'll try to convert 1MB card to 4MB version, requires large batch of 1MB x 1bit 80ns DIP chips.

Cheers,

Nice ! Think you will need 72 of those chips if memory serves me right (fixed my boo-boo). Hope it works !!

Daniël Oosterhuis wrote on 2020-05-14, 21:40:

Looks like it to me! The Slot 1/Socket 370 combo board is pretty cool too

Looks like a Jetway 911AF, I have one of those, too. And yes, the name is just stupid.

derSammler wrote on 2020-05-15, 06:50:

Daniël Oosterhuis wrote on 2020-05-14, 21:40:

Looks like it to me! The Slot 1/Socket 370 combo board is pretty cool too

Looks like a Jetway 911AF, I have one of those, too. And yes, the name is just stupid.

I think its Jetway 994AN-L as it has an ISA slot.

Didn't notice. But certainly a Jetway.

Here is a little game of Find the problem.
My new XT board just arrived, it was advertised as working.
My only question: why would anybody do that?

Miphee wrote on 2020-05-15, 08:18:

Here is a little game of Find the problem.
My new XT board just arrived, it was advertised as working.
My only question: why would anybody do that?

Is it working after correcting the problem? Somebody might have been curious and not knowing what they were doing?

They did not test it though 😜

Miphee wrote on 2020-05-15, 08:18:

Here is a little game of Find the problem.

The CPU is inserted the wrong way?

Cyrix200+ wrote on 2020-05-15, 08:34:

Is it working after correcting the problem? Somebody might have been curious and not knowing what they were doing?
They did not test it though 😜

I just tried it in a different XT board and the CPU is fine. Swapped the CPU and the board is not starting at all. Tried this CPU, nothing.
The Juko board is dead. I can only think about one thing: He installed the CPU incorrectly to make it seem like I screwed something up that made the motherboard go bad. But I religiously check IC orientations because I screwed it up once in the past and learned my lesson.
Already wrote to the seller to explain this to me.
The fact that the CPU is working suggests that it was not turned on after it was incorrectly installed.

devius wrote on 2020-05-15, 09:10:

The CPU is inserted the wrong way?

Yes. It seems like the seller tried to pull a little trick on me.

I dont think something else than the CPU itself is going to be damaged by inserting it the wrong way? Maybe its just a configuration problem.

With these CPUs, not even the CPU itself will die. It only has a single GND and VCC pin, which are swapped when the CPU is inserted the wrong way. No current will flow in this case and no short is caused either.

The board was probably dead from the outset.

From my understanding the current will flow the reverse way when exchanging VCC and GND?

I inserted an EEPROM several times the wrong way. It gets _really_ hot but still worked after that procedure...

Received this POST card. Never used and comes with a 200 page manual. Seems to have much more features than the China-cards.

yeah, I inserted cache the wrong way (the right way according to the motherboard manufacturer) and they went smoking and are definitely toast after :p

so unless the 8088 has a reverse voltage protection diode I don't think it would survive would it?

Predator99 wrote on 2020-05-15, 10:04:

Received this POST card. Never used and comes with a 200 page manual. Seems to have much more features than the China-cards.

ah nice, I wish I had one of those ^^

Bought this new old stock Compaq CPU board with P133 + 82497 cache controller and a big cache of cache SRAM chips.

Having no Compaq system I have no use for it, but as a true Pentium lover I just couldn't not leave it there...

Predator99 wrote on 2020-05-15, 09:56:

From my understanding the current will flow the reverse way when exchanging VCC and GND?

I inserted an EEPROM several times the wrong way. It gets _really_ hot but still worked after that procedure...

Or it has an internal fuse that blows temporarily but I'm not sure. Either way I'm not going to test it. 😁
A 41256 RAM definitely burns if it is inserted the wrong way.

Predator99 wrote on 2020-05-15, 09:56:

From my understanding the current will flow the reverse way when exchanging VCC and GND?

No, since a transistor can not have the current flow the other way - it will block it. And early, simple CPUs like the V20 are made of transistors only. The CPU may get warm since some leaking current still creates heat, but unless you leave it in that state for a long time, it won't cause damage.

Ok that's interesting and new to me..

Got my reply: got blocked by the guy. I'll have to involve the auction site on this one.
Doesn't matter, wife got home with this:

A chess computer from 1979.

Miphee wrote on 2020-05-15, 08:18:

Here is a little game of Find the problem.

Apart from the CPU...
It may be just the picture but ISA slot 3 looks a little strange. Apart from that I wonder where did all those tantal caps at the RAM sockets go?