Sinclair QL Repairs And Restoration

[Noel] was in possession of two non-working Sinclair QLs and made a series of videos about his attempts to repair and restore them. If you don’t remember the QL, it was a computer by the famous Clive Sinclair and while it was ahead of its time in some ways, it didn’t become as ubiquitous as some of its siblings or the IBM PC. It did, however, develop an almost cult-like following. You can see the trilogy of videos, below.

The machine was sophisticated for its day–after all, the QL was for quantum leap. Based on a Motorola 68008 processor running at 7.5 MHz, the QL included 128 KB of RAM and could handle up to 896 KB, a respectable amount for 1984. It even had a proprietary network interface. However, it was especially well known for having a pair of microtape drives. These were nicer than cassette tapes but perhaps not as handy as floppy disks. They were, however, cheaper to put into a computer. While there was an official operating system, it wasn’t long before most QL users switched to Minerva, a better OS.

You can really see the differences in construction techniques for 1980’s consumer electronics and today. Of course, Sinclair was known to have reasonably inexpensive gear, so that contributes, too. One interesting thing about the video: [Noel] isn’t an expert on the QL so the video documents how he approached a new problem. Even if you don’t want to fix a QL, some of the process would be useful next time you are facing an unfamiliar board.

The two computers were slightly different versions. One had an unpopulated spot for an EPROM that the newer one didn’t provide. [Noel] built a simple adapter to allow an EPROM to work with either computer. Minerva’s EPROM had a diagnostic that identifies bad chips and that was very helpful with identifying the bad RAM chips. The second video covers some of the physical restorations and the third video covers the microdrives in detail. Overall, an interesting watch.

Sinclair was pretty obsessed with the microdrives, but they never really caught on. He did have a very interesting history in the electronics marketplace.

9 thoughts on “Sinclair QL Repairs And Restoration

  1. Moreover, Sinclair QL seems to be one of the first computer owned by Linus Torvalds. It was an interesting machine, I was very curious to see one but in those days I was too young to think about buying one…

  2. Sinclair wanted the full 68000 but it was far more expensive than the 68008 at design time.

    By the time it was ready to launch, the 68000 had dropped in price very close to the 68008.

    Looking at that demo, a 16-bit data bus would have done the world of good to the computer!

    1. I would have loved to have had a proper 68K on my QL. However, surely it’s not just the CPU’s price, but associated logic too. The DRAM and dual ROMs would be OK (since16 x 64KBit DRAMs can have a 16×1 organisation as can a pair of ROMs), but a 16-bit databus would have made the PCB bigger; and the ULAs would have had to be 16-bit too and perhaps the 8049 couldn’t be used (but maybe the 68K would have been fast enough not to need the 8049).

      1. Knowing how Sinclair worked, I’m pretty sure that a 16bit bus wouldn’t be an stopper for that: he would use the lower 8 bits and discard the upper ones for I/O, and reserve the full 16 bits only for memory.

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