Need help on PC-98 like Olivetti S-2260 computer

Started by 1ST1, November 20, 2022, 06:02:39 AM

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Hello, I am new to here, a friend pointed me to here. I am from Germany and I need your expertise.

Last year not far from here I picked up a machine for my collection of Olivetti PCs. But this one is very different from the other ones I have (see here). The guy who gave it to me told me that in the 1980's he has worked for a japanese company here in germany as a sales/service representative. And so he got this PC from his japanese company to look into spare part lists and so on. He told me that this machine is a japanese MS-DOS PC but not compatible to western models.

So now I have this machine, but no keyboard, no harddisk inside, no monitor. I have not tryed it yet as the power supply (special formfactor) is for 115V AC while here it is 230V and monitor connector is special.

Last year I started to research about this PC but expect two offers to buy such a PC in yahoo japanese website there was nothing. Finally by looking the boards and finding the two NEC D7220AD graphics chips I think it is something compatible to PC 98 standard as these ones have them as well.

So lets show some pictures which I posted last year on (here)

Front view of the machine

Rear view. The graphics connector are the two upper horizontal 25 pin ones as they are sitting on the graphics board. I see a standard DIN connector and I assume this is for keyboard, an external floppy disc connector and the blue one for printer, and the big vertical one with the red cover is on the harddisk controller. The other two vertical ones are serial interfaces as I identied the chip on the expansion card. But the rest? And I don't think that a standard AT keyboard would work here.

General view inside. It has no standard ISA slots, and they also seems to be different from those in NEC PC 98 machines (C-BUS).

The Ye-Data branding is present on all boards. I know that Olivetti cooperated with YE-Data under the Pegasus-Computers branding to produce M111, M211, M316 laptops in the early 1990's for worldwide sales.

Closer look to the slots. The processor is visible here in the square socket.

A closer look to the CPU and BIOS. The AMD-chip is a "Dynamic Memory Controller".

Full view on the mainboard after taking out the graphics card which is sitting on top.

NEC D72065 = Floppycontroller
NEC D8237AC = DMA-Controller
AMD Z8530AP = Baud Rate Generator, and Digital Phase-Locked Loop for Clock Recovery
NEC D8259 = Intel 8259 = programmable interrupt controller

A second 8259, this seems to be the same architecture as in every IBM AT compatible with cascaded interrupt controllers.
NEC D8251AFC = Programmable Com. Interface
NEC D8253C = Programmable Interval Timer
NEC D8255AC = Programmable Peripheral Interface

9 x 4 pieces of 50256 DRAM with 120ns. So in total 1 MB RAM matching to a 8 MHz CPU.

Opening the CPU sockets confirms that is an Intel 80286 at 8 MHz. So the PC is a direct counterpart to the european Olivetti M28 80286-8 AT class PC.

Top: The harddisk controller of the machine. As a comparison a typical 16 Bit ISA soundblaster card with standard ISA bus connector. That Olivetti S-2260 expansion bus looks very different. The Olivetti/Ye-Data harddisc controller has the following 'big' chips:
NEC D8237AC = DMA Controller
HN5264LP = static 8 kB RAM
NEC D726140 = Integrated Circuit Microprocessor for Hard Disk Controllers

AMD Z8530AP = Baud Rate Generator, and Digital Phase-Locked Loop for Clock Recovery, compatible to Zilog 8530
So that's why I assume that this is a dual COM port card.

And finally that card which sits on top of the mainboard, I identified this as the graphics card of the system, because...

... it has two of the NEC D7220AD graphics controllers what is typically for the early PC-90 PCs.

This add on card sits on the graphics card and it has a total of 384 kb video memory.

This one also sits in a slot of the graphics card. It has 6x Fujitsu 83100 ROMs, each 128kb. This should be enough space to memory japanese characters.

As a source to compare this PC to the PC-98 standard for me was and it shows up a lot of similarities, but at least the expansion slots are different from NEC/EPSON's "C-BUS". Other sources I have checked:

So that's what I found out. But no pinouts of the connector, no information what kind of harddisk, I assume it must be MFM or RLL, but which size/model/... and no operation system (japanese PC-90 MS-DOS?) and nothing else.

Can you bring more light to the dark?