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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 26th Apr 2016, 2:35 pm   #101
Graham-R
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Default Re: Strangest computer you have had?

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The Intersil 6100-series: basically a " |D|I|G|I|T|A|L| PDPn-a-chip".

See https://en.wikipedia.org/wiki/Intersil_6100_family
I believe it was related - the early Weather/Rainfall radars used PDP34's to do all of the data processing - the motor servo control being a separate box of discrete electronics. Later ones used a PDP/84.

I may still have a picture somewhere of the insides of Clee Hill WxR - when it being propped up with jacks as the concrete in the building had turned to mush.
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Old 26th Apr 2016, 3:16 pm   #102
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Default Re: Strangest computer you have had?

A minor correction. There is (as far as I know) no such thing as a PDP34. This is probably a PDP11/34 (a 16 bit minicomputer built mostly from TTL chips) and the PDP/84 is a PDP11/84 (a Unibus system with a DEC J11 chip as the processor).

The Intersil 6100 is essentially a PDP8 processor on a chip. This is a 12 bit machine.
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Old 26th Apr 2016, 3:55 pm   #103
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Default Re: Strangest computer you have had?

Yup, sounds about right.
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Old 26th Apr 2016, 5:52 pm   #104
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No as exotic as many in this thread, I still have a Yamaha CX5M that I bought new in 1985.
I knew someone (musically minded) who had the CX5M - basically an MSX computer with a synthesiser module bolted on - around about the same time as I was using an Atari ST and various standalone synths and modules. The CX5M was a nice machine for its time.

The same people (brothers who were friends of mine) virtually specialised in buying computers which were decent machines but ultimately never enjoyed mainstream success in the UK.

They had a Tatung Einstein as well.
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Old 26th Apr 2016, 7:13 pm   #105
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Default Re: Strangest computer you have had?

Possibly not quite the computer but an interesting effect. While at college I came across a Zilog Z80 based microprocessor development system (I would have to search to find the model) that someone had added to with LED outputs on the ports. I remember programming it for sequential output (bit like modern LED disco lights). I found that the light sequence flashes slowed down steadily to a standstill then if left the system crashed. An easily spotted problem - The 5V IC regulator was overheating. I found that if I blew strongly on the regulator to cool it down at the point the flashing stopped things speeded up again and ran Ok until the regulator got too hot again (obviously self limiting).

It didn't half amuse me at the time as, until then, I thought digital systems ran to the clock.
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Old 27th Apr 2016, 10:20 am   #106
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Default Re: Strangest computer you have had?

The posts on the previous page referring to mechanical calculators reminded me that this is the oddest computer I have ever owned:

https://www.youtube.com/watch?v=JvJPjugtenI

I've posted about it here before, and the thread is here:

https://www.vintage-radio.net/forum/...ad.php?t=81707

As I used to make a living teaching acoustics and vibration, nearly all of which assumed linearity () and relied on Fourier, I was very glad to pull this thing from someone's bin, all the more so when the penny dropped as to what it was.
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Old 28th Apr 2016, 4:06 pm   #107
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Default Re: Strangest computer you have had?

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A minor correction. There is (as far as I know) no such thing as a PDP34. This is probably a PDP11/34 (a 16 bit minicomputer built mostly from TTL chips) and the PDP/84 is a PDP11/84 (a Unibus system with a DEC J11 chip as the processor).

The Intersil 6100 is essentially a PDP8 processor on a chip. This is a 12 bit machine.
Yes, I seem to remember the main boards in the PDP11/34 were absolutely crammed with discrete IC's, in operation we used to have to manually 'time' the rotation of the dish to start at the correct point so the clutter maps would be lined up.

The service engineer from DEC used to drive a Ford Escort Turbo, an odd juxtaposition of technology - but the curious thing was the ECU in the Ford used to cause the car to 'break down' just before the service was due....... at least that was his interpretation.

Later Weather (i.e. Rainfall) Radars used the astronomical power of the PDP11/84, Doppler versions used various Sparc based systems.

The Analogue computer used in the Wind Finding Radar (the Cossor beast) was called the Data Acquisition Unit - it was considered quite advanced....

I thought it was an impressive piece of design work considering what it had to do (and not a piece of dried seaweed in sight.)

Last edited by Graham-R; 28th Apr 2016 at 4:12 pm.
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Old 28th Apr 2016, 4:41 pm   #108
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Actually the PDP11/34 is one of the simpler TTL-based PDP11 CPUs. It's only 2 boards, so figure on around 200 ICs. My PDP11/45 has around 1000 TTL ICs for the main CPU and another 400 or so for the floating point option. That's not counting memory or peripheral controllers, of course

As an aside, the frontpanel keypad and display on the 11/34 are controlled by an Intel 8008 microprocessor.
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Old 28th Apr 2016, 5:03 pm   #109
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Default Re: Strangest computer you have had?

I have had to dredge my memory banks on this - it was over 25 years ago...

The PDP in the weather radar usage was a 6-7 feet tall rack and had a reel-to-reel tape drive and a RAM bank - I think it was this that I was thinking of when I mentioned lots of IC's.

It also had a clanky old teletype attached to it.

I really wish I had kept the photographs I took, as I can't find them means I must have disposed of them, I do have some of the Radar/DPU & DAU manuals/training materials somewhere though.
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Old 28th Apr 2016, 5:22 pm   #110
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As an aside, the frontpanel keypad and display on the 11/34 are controlled by an Intel 8008 microprocessor.
That reminds me of the Cray T3D supercomputer at http://www.epcc.ed.ac.uk/ which had an Apple Mac PowerBook concealed inside to serve as its "front panel display".

And don't forget - the original design-intention for the IBM PC was that it would serve as a console to the big 30xx-series mainframes of the day to allow a degree of command-automation!
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Old 2nd May 2016, 5:25 pm   #111
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An absolute gem. I'd have loved one of those before computers came along...
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Old 20th May 2016, 12:52 pm   #112
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Default Re: Strangest computer you have had?

I'm not sure if you can call it a computer but I remember my Dad giving me his old psion p250 from BT. There really isnt much I can do with it since he's forgotten the password but I certainly had a lot of fun fiddling about with it when I was little.
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Old 20th May 2016, 12:58 pm   #113
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I was given an old, lumbering German Lap Top....the make escapes me and it turned out the company no longer made lap tops.....but they had switched to making pornographic video film productions instead !!
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Old 22nd May 2016, 10:08 am   #114
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My Sinclair ZX81 was ordered as a kit from the UK in the early 80'ies.
One strange ting about it is that it actually worked when assembled.
Another strange thing is the Sir Clive promised it would have the brains to run a nuclear power plant.
I never got around to building one of those so I don't know if he was right

It did enable me to learn quite a lot about programming the Z80 CPU, something that came in handy later on with my New Brain with CP/M.

If you don't think a ZX81 is strange enough for this thread I also had a variant of the same, the Timex-1000.
It sported a much improved keyboard, the socalled 'Dead Flesh' type much like later Spectrums.
It wasn't the original Timex-1000 but a variant sold through supermarked-stores for the European marked (PAL Modulator) and it was labelled with a brandname that I forgot.
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Old 24th Jul 2016, 4:12 pm   #115
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Default Re: Strangest computer you have had?

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I've got all sorts of forgotten failures hanging around the place (Camputers Lynx, anyone?)
I remember the Camputers Lynx Home computer. One of the few (apart from the Ubiquitous BBC Micro) that had a Basic that when you ran a typed in program it compiled the Processes so the next run would be faster. it also had the ability to enter Line Numbers in decimal fractions and it accepted them. I had a 48k Sinclair Spectrum (later transferred into a D'Ktroniks keyboard) but my favourite was the 512k Sam Coupe. with its 8Mhz variant of the Z80 as CPU and 16 bit graphics. The sound chip was brilliant and I often rewrote 128k Spectrum programs to use the same ports the Sam used to get the sound to work properly. My oddest has to be one I still have A Sharp Pocket PC (looks like a glorified calculator). I sadly erased the Programs that were on the Ram cartridges. (Stock taking and stock control written in Sharp's Basic)
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Old 24th Jul 2016, 4:19 pm   #116
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If you don't think a ZX81 is strange enough for this thread I also had a variant of the same, the Timex-1000.
It sported a much improved keyboard, the socalled 'Dead Flesh' type much like later Spectrums.
It wasn't the original Timex-1000 but a variant sold through supermarked-stores for the European marked (PAL Modulator) and it was labelled with a brandname that I forgot.
I can go one better. Before Sinclair produced the ZX81 they did the ZX80 in the vacuum moulded white bubble case. But long before that Science of Cambridge (Sinclair's company) they released an experimenting unit for the Z80) cpu. it was called the Mk14. You "programmed"" it in Hex and read the results on the built in Led display (this was before the Sinclair Pocket Calculator). Enthusiasts of the Mk 14 were encouraged to add control modules and a thermal spark printer board.(Later used with the ZX81 and Spectrum computers) Before it was dropped in favour of the ZX80, there even came a modulator board to get a display on a black and white monitor/TV.
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Old 24th Jul 2016, 5:47 pm   #117
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Default Re: Strangest computer you have had?

I think you are getting somewhat confused. The MK14 did not use a Z80, it used the National Semiconductor SC/MP processor. It also came out long after some of the Sinclair pocket calculators like the Cambridge, Scientific, etc.

I don't recall an official spark printer board for the MK14 either. There was a cassette interface, PROM programmer and VDU, certainly. The last took up a lot of the machine's RAM for video memory (didn't you have to fit the 256 byte RAM expansion and the RAM/IO chip (8154) to use it?)
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Old 24th Jul 2016, 8:59 pm   #118
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Yes, the MK14 VDU virtually crippled the MK14 by pausing the CPU while it was reading screen data from the 512 bytes of system ram that it used as screen RAM, and by using nearly all of the system RAM (both original and optional) as screen RAM, so the only RAM left over for actual program code was the 128 bytes in the optional INS8154 RAM/I/O chip.

There was no official printer for the MK14 - I can't remember if the famous spark printer was launched with the ZX80 or the ZX81, probably the latter because it was made in matching black.

But it's good, anyway, to hear from yet another person who had, or still has, an MK14. (There are several of us here).
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Old 24th Jul 2016, 9:10 pm   #119
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Default Re: Strangest computer you have had?

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My Sinclair ZX81 was ordered as a kit from the UK in the early 80'ies.

Another strange thing is the Sir Clive promised it would have the brains to run a nuclear power plant.
I never got around to building one of those so I don't know if he was right.
I can just imagine it : "I don't care if we are in danger of a "melt down", it takes 10 minutes to re-load the program from tape" <Block Error> "oh damn" *BOOM*.
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Old 25th Jul 2016, 8:09 pm   #120
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I've just given one of my ZX81s a new lease of life by (reversably) grafting in a low-power 62256 static RAM in place of the original 1K RAM.

It gives you the undeniable aesthetic beauty of the basic ZX81 wedge design combined with the actual amount of RAM it needs to do anything useful. Looks like a 1K ZX81, but is a 16K ZX81, without the ugly, power hungry, crash prone RAM pack dangling off the back.

In its most basic form, the 62256 modification uses just half of the capacity of the 62256 to provide a reliable internal equivalent of the 16K RAM pack, with the other half not utilised.

With a couple of additional gates the other 16K can be made to appear at 48K->64K - the operating system can't use it directly but you can put your own data (machine code, etc) in it. However, this extended form of the mod is less easily reversable as it may require track cuts on the ZX81 PCB, something I just won't do.

Plenty of info about both forms of the mod around on the net.
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