Your First Computer versus Your REAL First Computer

Episode #45 of the “Retrocomputing Round Table” podcast posed an interesting topic:

The first physical computer you used versus your spiritual/emotional first computer… and this can be split into “owned” verus “had access to” to make upto two topics.

First Physical:

The first physical computer I had to use was a Research Machines 380Z at school in 1980. These things seemed to have leeched their way into a huge number of high schools in the UK (I keep running into people that remember them fondly), but had absolutely *zero* presence outside the UK. And as at most schools, there was just the one unit, which had to be timeshared amongst the entire computer studies class. There was quite a black market trading “time at the console” in return for lunch tickets, sweets, do-your-homework-for-you and so on!

The really neat feature of the RM380Z, for it’s time, was the bitmapped/vector graphics capability – once trusted as “senior” class members, we got plenty of console-time playing Lunar Lander in glorious high-res monochrome graphics (oops, I mean plenty of time completing educational programming project work). The school also had a CBM PET of course, but we didn’t pay it much attention. Around that time, I did also muck about with a friends personal ZX80 (yeah, he actually *owned* a computer – WOW).

Spiritual Computing Home:

My emotionally first computer was another I didn’t own – at my first job working for a software house in 1983, we used British-designed and manufacturered Integrated Micro Products’ IMP-68 computers with dumb ASCII terminals.

The IMP-68 was an odd beast: an S100 bus 8-slot backplane with a custom 8MHz 68K CPU board, custom memory boards, a Cromemco (remember them?) C3 floppy controller, a dAVID Konan Junior MFM disk controller, and a 6Mb, 12Mb or trully massive 20Mb hard-disk drive – running a UNIX V6 clone (Idris) that didn’t require memory-translation hardware (unlike AT&T UNIX). Idris could take advantage of an MMU if present, but did not absolutely require one. The IMP-68 could also run a ported version of AT&T UNIX v7, thanks to work done by Uniplus.

More wierdness, the custom MMU boards that slotted into the 4MHz backplane were connected to the CPU board by a dedicated 8MHz ribbon-cable: a “local bus” some 10 years before the PC world went “local bus” crazy.

Mind you, there were risks – the internal unshielded power-supply unit included a *house-brick-size* pair of eletrolytic capacitors. Considering that tiny 0.5″ capacitors can be decidedly harmful to humans, these suckers could have turned you into a humanburger if you weren’t *very* careful with your fingers and screwdriver! They even *looked* threatening.

The Recovery and Repair Adventure:

Eventually, when the company had no further use for the IMP-68s, a colleague and I took ownership of the two (mostly) surviving units, and managed to locate another unused one in London. I flew across the water to London to salvage components from it, and carried them back in my luggage – including a 20Mb 5.25-inch full-height disk drive which airport security took an immediate dislike to – a hermetically sealed large metal box with elecronic components on the base – they thought it was a bomb!

After a considerable amount of time haggling, and eventually borrowing a mains-to-5VDC adaptor from another passenger, and a bit of custom on-the-fly wiring, I managed to demonstrate it flashing it’s LEDs to the security personnel, at which point they lost interest in it – either their bomb-identification procedures weren’t too clever, or I had bored them into submission šŸ™‚

But by this time the airport gate for my flight home had closed, ouch!

Fortunately, I managed to persuade one of the airline personnel (who just happened to be wandering past on their way to a different gate) to eyeball my boarding-card and get me onto my flight, but I had to travel out to the plane on the last of the baggage cars, sitting on top of my suitcase full of computer parts with the wind blowing in my hair. The steward had to reopen the passenger door to let me onto the plane!

End of the story – we managed to restore two IMP-68s into fully-working condition using the components I had brought back.


Around 1990, we were asked by the British Museum if we could donate one to their collection, as the very first British-designed and British-manufactured UNIX system. I don’t know if it is still in their collection…

As you may imagine, after all that shenannigans, I still have a place in my heart for the slightly wacky IMP-68.

Your Turn:

If you want to let others know the distinction (if any) between your first physical-versus-spiritual computers, and the reasons, go add your comment to the “First computer vrs first REAL computers” thread in the “Retro Podcasts” section of the Vintage Computer Forums.

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