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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 20th Aug 2016, 1:07 am   #1
JohnBHanson
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Default Gemini 80 bus computers

These were a development after the nascom range. I have some working cards - is there anyone here that has any interest in these computers?

PS. I have also written an emulator for linux
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Old 20th Aug 2016, 7:20 am   #2
acollins22
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Default Re: Gemini 80 bus computers

I'd be interested in this.

I was seriously looking at buying its predecessor, the Nascom 1 back in the day I rather regret not doing it.

The Gemini really looks fascinating.

Cheers,

Andy.
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Old 20th Aug 2016, 9:11 am   #3
JohnBHanson
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Default Re: Gemini 80 bus computers

Just discuss, but if anyone has any interesting software.

About 10 years ago I had a large 80 bus system. It had
1 GM 813 - z80 processor with memory management
2 MAP256 extra 256Mb ram card
3 GM832 monochrome 80 column video card
4 GM849 Floppy and SCSI interface card
5 100MByte hard disk
6 Afron speech card (Based on Digitalker)

I ran BDOSZ and CCPZ - Z80 extensions to CP/M with a few extra facilities. I even wrote a multi console extension which gave 65536-512 bytes to each console for the user program and could swap between 8 programs per console. I had a lot of fun with it and even did some real work.

I have not run the hardware in about 10 years but I am slowly de-mothballing it. I copied the hard disk to linux and wrote an emulator. About a couple of years ago I built from veroboard a card to plug into the backplane and connect to my linux box. Now my linux emulator can drive real hardware. Currently I have it driving the GM832 card and the Afron speech card. Somewhere on the line I have accumulated a PLUTO2 card which I now have working thanks to another member of this forum who gave me a monitor that was compatable with it.

Still having fun.
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Old 20th Aug 2016, 3:30 pm   #4
TonyDuell
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Default Re: Gemini 80 bus computers

Somewhere I have a Gemini Galaxy. I think there are 3 boards in the cardcage, CPU, video and disk (floppy + either SASI or SCSI, I forget). There is a separate board to convert that to go to an ST412-interface hard drive.

I also have the little network card that hangs off a parallel port on (I think) the CPU board. The one with a UART and not that much else on it. Somebody had scraped the numbers off the ICs on that, presumably to prevent copying, it took me all of 15 monutes to figure it out.

I also have the original keyboard and (Hantarex) mono video monitor.

Amzingly I got a Torch-branded light pen for the BBC micro that turns out would plug directly into this machine.

I believe this machine was used at Henry's Radio (as in Edgware Road), who were a Nascom dealer. It certainly shows signs of use rather than just being a bit of old stock they didn't sell Alas anything interesting was wiped from the hard disk before I got it.
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Old 20th Aug 2016, 3:42 pm   #5
JohnBHanson
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Default Re: Gemini 80 bus computers

I remember the network, attached to a PIO. Do you remember what the uart was - I suspect an 8530 - but never looked that closely.

Shame the hard disk was wiped.
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Old 20th Aug 2016, 4:04 pm   #6
TonyDuell
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Default Re: Gemini 80 bus computers

Well, at least CP/M was left on the hard disk, so I can boot it.

The UART on the network card was just one of the dumb UARTs of the AY-5-1013 type (I think a +5V only one). Not a synchronous serial chip. IIRC the network board was that, a fixed-frequency clock generator (I forget the speed) and some kind of differential line driver (RS485 kind of thing). I will have to see if I can find the schematic I traced out for it.
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Old 23rd Aug 2016, 1:15 am   #7
mole42uk
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Default Re: Gemini 80 bus computers

I have a NASCOM 2 and several Gemini cards as well as a 5½" floppy drive.
Don't remember what's there but I have a box of floppies for it if anyone cares to do copies I'll have a look and catalogue them.

I did once have an 8" hard drive attached to it but that went to the graveyard years ago.
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