It is probably only compatible with certain arrangements of ram.

Think of it kinda like a spreadsheet.

It might support 64 columns, 32 rows and 8 sheets.

But you have 128 columns, 16 rows and 16 sheets.

Look to the board manual, and the memory stick/chip datasheets for clarity.

It is very difficult for me to find a manual for this APRICOT model. I have one for Aproicot XT, 486, but I haven't found one for 386 XEN-S yet.

By the way, after inserting only new 4MB memory, it detects them and there is still 3072KB....

makary23 wrote on 2025-01-23, 07:39:

I installed additional RAM sticks in Apricot XEN-S 386 16MHz. It was 4x1MB but in the BIOS it showed me 3072 MB + 640KB. Now, when it is 8192MB, it shows the same despite the correct jumper setting.

In the BIOS program, setup.exe, when set to 8192MB, shows that this value is incompatible. So it only detects 3072MB again. What's wrong?

Of course, this is about KB, not MB

Look for the chip datasheets.

Ie the individual ram chips.

The board might only accept "the same" arrangements.

It's likely that they're different. If they happen to be the same, then it is likely that the board or chipset left off some of the address lines and it can only address 4mb (possibly with that arrangement)

The chipset datasheet should help confirm or rule out the chipset being the limitation.

Ram is not exactly my forte, but there are some real experts here who will probably see this eventually.

Thank you very much for your willingness to help, I am sending photos of the 30 pin SIMM memory. Maybe someone can explain why this is so?

Why are you mixing SIMMs in the memory banks? Unless this motherboard has a very unusual arrangement, put the same 4 SIMMs in each bank.
Also please show us the BIOS screen where you specify the installed memory. What was initially written there with the 4MB, 4096, 3712, 3072, something else?

I mix memories in banks according to the etiquette in the first post.

The arrangement of memory is, in my opinion, correct.

BIOS below in the photo.

makary23 wrote on 2025-01-23, 09:49:

I mix memories in banks according to the etiquette in the first post.

The arrangement of memory is, in my opinion, correct.

BIOS below in the photo.

Oh you are right, the memory banks do have an unusual arrangement.

So you are changing the "Extended Memory" property and I assume you can write freely and not choose from some prepopulated values.
Again this is the extended memory size only, not the total amount. Since you don't have 4096 for the 4 SIMMs, you should also not have 8192 for the 8 SIMMs there.
My suggestion is to try the value 7168 (existing extended memory 3072+4096 of the additional 4 SIMMS=7168, or if you prefer the total of 8192-640-384=7168)

I entered 6144KB = 3072KBx2

Then I entered 7168 KB

The effect is the same - photos below.

These values ​​are not consistent with the memory - as if he didn't want to address more than 3072KB.

Could you do a test to see if the four banks you added work?
Set the configuration to 4 MB, and try the four banks, that is, remove the original working ones, and put the ones you added to get 8 MB, try to start, if it starts and reads them ok, if it doesn't start explain why you don't see them.
But in case you read them, that is, it also starts with the other 4 MB, it is possible that they are incompatible, in that case you should find eight SIMM 30 PINs identical, because the ones you have now are four of one type and four of another, even if they have a chip in common.

HEY,

both the new 4x1MB chips and the old ones that were previously 4x1MB work in bank configuration 2,4,6,8 and in configuration 1,3,5,7!

I have no more ideas.

Maybe these bones really can't work together, but what should we look for...

I have another question - why is the value of 3072KB correct when the value of 4096KB should be?

You can edit your first post and change the MB into KB.

What chipset does your mainboard use ?

makary23 wrote on 2025-01-23, 16:10:

I have another question - why is the value of 3072KB correct when the value of 4096KB should be?

The 4096KB are split into three parts: 640KB "conventional" memory and 3072KB "extended" memory. Furthermore, the way the chipset and the AT architecture works, without special means you will get 384KB of memory at numeric addresses that are reserved for non-memory purposes (VGA video memory, BIOS extensions, ROM BIOS). This special memory might be used for special purposes on some boards (usually ROM shadowing), but it is not usable as "standard RAM". So 640 conventional + 384 special + 3072 extended is exactly 4096.

weedeewee wrote on 2025-01-23, 18:39:

You can edit your first post and change the MB into KB.

DONE.

What chipset does your mainboard use ?

FOTO - CHIPS P82C206 ?

mkarcher wrote on 2025-01-23, 18:51:

makary23 wrote on 2025-01-23, 16:10:

I have another question - why is the value of 3072KB correct when the value of 4096KB should be?

The 4096KB are split into three parts: 640KB "conventional" memory and 3072KB "extended" memory. Furthermore, the way the chipset and the AT architecture works, without special means you will get 384KB of memory at numeric addresses that are reserved for non-memory purposes (VGA video memory, BIOS extensions, ROM BIOS). This special memory might be used for special purposes on some boards (usually ROM shadowing), but it is not usable as "standard RAM". So 640 conventional + 384 special + 3072 extended is exactly 4096.

Now, I understand, Thank you!

makary23 wrote on 2025-01-23, 19:02:

weedeewee wrote on 2025-01-23, 18:39:

You can edit your first post and change the MB into KB.

DONE.

What chipset does your mainboard use ?

FOTO - CHIPS P82C206 ?

Dang, plenty of discrete logic chips and a P82A203? I'm out 😀

Production date is around the crazy years of 1988 😀

Apricot in action :

https://youtu.be/exMPG1aeuys

The question about RAM arose because I wanted to install Windows 3.11 on Apricot and I know it would be possible, but I have a memory error at 4MB.

So I bought more memory and by the way I only tried installing on these new RAM (only new 4MB)

I guess I need to start a separate thread about this error?

In both cases (old RAM and new) when installing windows there is:
Memory Parity Interrupt AT 0DBB:0190

makary23 wrote on 2025-01-23, 19:20:

Production date is around the crazy years of 1988 😀

Apricot in action :

https://youtu.be/exMPG1aeuys

Is it a 386sx machine ?

according to this little pdf https://www.1000bit.it/ad/bro/apricot/apricot … en-s-series.pdf
maximum memory on the mainboard is 5M, which would mean 4x1M and 4x 256K

edit: just noticed your power supply indicates XEN-i. not XEN-S as your subject indicates :-p

edit2: dip switches can be finicky, especially older ones. have you measured their on resistance?