Positive Graphics Controller? Heh. That's a really interesting find! I didn't even know such a card existed. I've been looking for a way to upgrade the graphics capabilities of my Dad's M24, the monitor of which also has such a 25-pin video connector. I wonder if that monitor would also work with this card...

What I've been wanting to try as an alternative is to get the EGA Wonder 800 (not 800+) to work with that monitor, since it supports the monitor's 25KHz horizontal sync frequency. It needs a dumb 9pin-to-25pin adapter, but other than that, with the right dipswitch and jumper configuration, the monitor should be able to work with that card.

Thanks for sharing this document! I knew about the OEC and OVC cards for the Olivetti M240, but not this one. And here I was, thinking that I knew most there is to know about the proprietary graphics cards and mode in Olivetti systems. A whole new treasure trove of information. 😅

digger wrote on 2023-05-27, 18:16:

... I've been looking for a way to upgrade the graphics capabilities of my Dad's M24, the monitor of which also has such a 25-pin video connector. I wonder if that monitor would also work with this card...

I see you're from The Netherlands... I hope you don't mind me asking how your Dad came to own an M24? We had one in house growing up and the reason we had an M24 was because my Dad used to work for the bank (ABN back then, ABN AMRO nowadays). If this is also the reason your family also had an M24 then I have a favour to ask... 😀

When my family acquired the system (in the late 1980's, probably 1987 or so) the system came with a bunch of software, some disks where Olivetti branded and it had some software (written in GWBASIC) that explained the M24, Getting to know your M24, which you can find on Jim Leonards FTP site [1].

However, it seems that that the M24 distributed in The Netherlands back then through ABN also included a bunch of other software. There was some productivity software (word processor, spreadsheet and a database management which I can't remember the names of). There was also a disk with a bunch of games, mostly written in GWBASIC.

I was wondering, if you happen to acquire your family's M24 through ABN and if your system came with those productivity software & games, if you'd be willing to share a copy of those disks?

[1] ftp://ftp.oldskool.org/pub/drivers/Olivetti/M24/Software/

Hi @pan069,

Indeed, my Dad acquired his M24 through the PC Privé program, a tax incentive by the Dutch government to encourage people to purchase PCs from their employers for home use, allowing them to pay for it by subtracting the purchase cost from their gross salaries, without having to pay income tax over it.

And yes, he worked for a bank, but not ABN.

Funny enough, our neighbor did work at ABN, and she also purchased an M24 through her employer, also taking advantage of the PC Privé program.

You make a really good point about the supplied Dutch software needing to be preserved! Indeed, I remember it coming with graphically animated "Welcome to your M24" intro software, in Dutch, making use of the proprietary 640x400 high resolution mode.

Also, some educational software was supplied, including manuals and such.

I have no idea when I'll get around to it, but I've wanting to archive all the old disks that My Dad had in the attic anyway. I should indeed also scan the documentation that came with it. I'll see when I have time to pick up that project.

Predator99 wrote on 2023-03-14, 20:52:

Anybody seen this card before? This seems to be the Olivetti GO423 (Positive Graphics Controller)? […]
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Anybody seen this card before? This seems to be the Olivetti GO423 (Positive Graphics Controller)?

P.G.C. GO423 (Positive Graphics Controller) For M240 - M280 - M290 - M380

https://minuszerodegrees.net/manuals/Olivetti … 20computers.pdf

It can display up to 640x480. But no code in the ROM, seems not to be an EGA card, more related to CGA? Connector is DB25.

Looking at the chips on the card, it's definitely not technologically related to EGA. The EGA card's prime technological property is the video memory built from DRAM, with an internal 32-bit video memory data bus. This card is designed entirely different. It contains only SRAM. It has 4 Chips 16K x 4, that will provide 32KB of video memory. This is a nice amount for "enhanced CGA", and might be accessed at 16 bit width (which again makes a lot of sense both for bandwidth requirements as well as serving character bytes and color codes in text mode at the same time). Furthermore, the card has two chips 4K x 4, which will provide another 4KB of SRAM memory. This is in sum makes 36KB of memory, which is 294'912 bits. This makes me wonder how they can run the 640x480 graphics mode, which has 307'200 pixels. In text modes, the 4KB extra SRAM might be used as font RAM. So you could get some EGA features from that board, like software defineable fonts, higher graphics resolutions, but no way to get 640x350 at 16 colors with that hardware.

The video timing is generated by the HM6345 CRTC, which is very similar to the Motorola 6845 CRTC used on CGA, MDA and Hercules. So I agree this design looks more like "pimped CGA" than "EGA".

digger wrote on 2023-06-18, 11:51:

I have no idea when I'll get around to it, but I've wanting to archive all the old disks that My Dad had in the attic anyway. I should indeed also scan the documentation that came with it. I'll see when I have time to pick up that project.

Thank you very much!