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Olivetti PCS86 ram expansion info

mamaroma

Member
Joined
Dec 1, 2022
Messages
18
Location
Italy
Hi all,
Sorry for the english translated by google.
Unfortunately there is not much information on the olivetti, I'm trying to get the additional ram recognized and for this I would need to understand what the switches on the motherboard do.
The ram should be handled by the 3 switches nearby. Your pc should handle up to 2mb of expansion.
For now I replaced the floppy with a 1.44mb and inserted an xt cf lite with 32mb compact flash.
Does anyone have a manual or information?

Thank you
 
The pc has two expansion slots and does not accept a single sim.
I also tried to put two 256K simm and the system see a total of 640 + 384k but the dos always continues to see only 640k.
I've tried all the combinations of the three jumpers but nothing changes.
If I put two simm of 1mb or higher it sees 640k + 1920k but in dos always only 640k.
I wish I could find a service manual or something where the functions of all the jumpers are indicated.
 
The 256 kB SIMMs are the correct ones for the PCS-86.

MS-DOS can not access more than 640 kB.

If it can see 640k + 1920, then it is not the PCS-86, it then should be the PCS-286 or PCS-386SX.
With the PCS-286 you can install the HIMEM.SYS driver, then software for 80286 processor like Windows 2.0 / 3.0 can use the full memory. With a PCS-386 you also can install EMM386 memory manager and can use Windows 3.x.

The pc has two expansion slots and does not accept a single sim.
This is correct for 8086, 80286 and 386SX processor, they all have 16 bit data bus, and as a 30 pin SIMM has only 8 Bit data bus, allways two of them are required.
 
I succeeded, on the motherboard there is wdc fe2011 management chip which can manage up to 2.5mb ram. I'm attaching it in case anyone needs it (mm.sys)
 

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After another italian specialist explained me, now I understand... This is very special and unusual for an XT class PC. That chipset seems to have EMS-LIM support. So EMS memory is not adressed directly (like on a 286) but with 16kB adress windows inside the 1st 1MB which is adressable by the V30 CPU. This also means, that accessing that memory is not that fast than the memory in the first meg (640 kB).

So anyhow, standard MS-DOS applications can not use more than 640 kb. You need software (and probably drivers) to support EMS-LIM memory. This is for example Windows 2.x and definitively 3.0.
 
yes, it has a dedicated chip, the driver was needed which still consumes base memory. The dos can't be loaded higt so it becomes almost useless, I'll do some testing with various programs.
 
The FE2011 chipset is quite powerful in terms of LIM-EMS support. Before the motherboard died, I was able to do some experiments with the PCS86 and various memory managers. The MM.SYS driver uses any free upper memory area for the EMS page frame, so you can have more than the standard 64 Kb window.
If you pair it with QRAM 2.02, you can have upper memory and expanded memory at the same time. So you can load dos and some drivers high to save conventional memory, and use more than 640 Kb of memory with programs that supports LIM-EMS.
 
thanks davide78, in fact I did not understand how to load dos in high memory, I will download qram and as soon as possible I will do some tests.
 
thanks davide78, in fact I did not understand how to load dos in high memory, I will download qram and as soon as possible I will do some tests.
With QRAM and DOS >= 5 you can use DEVICEHIGH and LOADHIGH to load device drivers in upper memory. To load also portions of the dos kernel high you need DOSMAX: https://ftp.sunet.se/mirror/archive/ftp.sunet.se/pub/simtelnet/msdos/sysutl/dosmax21.zip
Where to find the qram driver?
 
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