Clive Sinclair died

[John Rumm]

Yup, saw that - another figure from my tech formative youth gone...

I built a ZX80, but then jumped ship to a VIC-20 later...

[Harry Bloomfield, Esq.]

pinnerite was thinking very hard :

He began, buying sub-standard transistors in bulk, testing them and reselling the usable ones.

[Jim GM4DHJ ...]

typical business UK failure...

[The Natural Philosopher]

Z12 is the only power amp I have ever seen that you could actually see the crossover distortion on, on an oscilloscope.

[The Natural Philosopher]

He began, buying sub-standard transistors in bulk, testing them and reselling the unusable ones.

[Mark Carver]

Just dragged out of storage my Sinclair Oxford 300 scientific calculator. I found it in the loft a couple of years ago, and it still worked. Today, stick a new 9v battery in and it's dead. (It draws 20mA when switched on, so not a case of the batter clip wire having fractured etc.)

[Brian Gaff (Sofa]

I built the zx 81 with my limited sight, and had a Spectrum, indeed many of them even some of the Amstrad ones. I learned a lot about computers since both machines came with excellent manuals for actually writing your own software. Yes it was slow and had blocky graphics by today's standards, but it showed the principals. I was also unfortunate enough to be at the Ally Pally launch of his C5 electrically assisted pedal car, which I think would have been a great summer recreational vehicle, but it was launched in a blizzard and it was white so the press had a field day. QL, well, never really tempted since it was a very restricted 16 bit computer with an 8bit buss. It had many incarnations of course, TheICL One per desk had the same basic innards plus a telephone and a modem. There were third party keyboards, even replacement motherboards that allowed full 16 bit versions of the Motorola processor, but it was killed off by the Atari ST and Commodore Amiga designs in the end.

It is a real shame that nobody packages an easy to understand basic programming language with their computers any more, as a lot of people are now users, but understand nothing about how the thing does what it does and are always frightened of busting it.

His other Successful computer of course being the first viable portable for Journalists etc, the almost indestructible Z88, coffee resistant machine

Long before computers he published books of circuits for home electronics projects and sold cheep audio gear aimed at the diy market. All seemed to work well, I still have a couple of his IC12 amps in my shed. I had the IC10, and his z12, and his fm tuner and stereo decoder as well.

I met him on a couple of occasions, once when he wads plugging the z88, and earlier when he visited where I worked looking for a company to build his pcbs for the diy market.

. Brian

[Brian Gaff (Sofa]

I had very little issue with Microdrives on the Spectrum, the main problems I had with them were dodgy edge connectors.The later carts were a lot better. The early ones use BASF Chrome, the later ones used Maxell hi bias tape. The latter being a better product in my opinion. Ablex who made the actual plastic bits seemed to have the reliability sussed quite fast, but being wound a bit like an 8track cart they could of course eventually seize up as the used lubricated tape. Not enough storage space killed them off, Waferdrives were a bit better, a kind of bigger version of Microdrives often found in midi instruments of that era, but loading was slower of course as there is no random access on a loop of tape!

The four tracks across such a narrow tape with such basic engineering always fascinated me. Brian

[Brian Gaff (Sofa]

Not if you followed the advice in its manual, and did not try to run it at almost its max supply volts. He always a bit optimistic about his power ratings, as they were peak power, not rms power, thus the z12 was a six watt amp really. You could also tweak the biasing so it ran closer to class A/B to remove some of the crossover distortion it could generate when cold. It used mostly Germanium transistors, and they were notorious for their drift with heat, despite a thermal probe on the heat sink, this was far too slow to make the difference other then stopping overcooking. You obviously sacrificed some power buy running the output this way, so you then probably had a 3 watt amp instead!

Brian

[Brian Gaff (Sofa]

2N3055, actually were pretty robust, it had to be a flaw in the circuit. I used to use those in my linear adjustable psus years ago. There was a Fairchild version as well which if I recall would actually run at several megahertz so pirate mw radio transmitters used them in the pa stages grin.

Brian

[Brian Gaff (Sofa]

I never killed mine. You needed to keep your psu below ever going near the so called max power rail voltage, and fit some little network of resistor and capacitor on the output as well. It was the output devices that were suspect I think. Sinclair had a track record of buying up cheap components that were out of spec and using them. Most of the time he got away with it, but in the Spectrum he bought ram chips with one half not working and put links in the pcbs to make the correct bits work. Problem was if you fitted new chips from Sinclair it might well be the other half that worked so you had to move the link. East London Robotics produced an 80k mod for thee machine by fitting non faulty chips and a piggy back board to switch banks of ram from an io port, a technique Sinclair then nicked to make his 128k Spectrum designed in Spain. Timex in the meantime made moor hi res modes on their machines instead. Brian

[Brian Gaff (Sofa]

Which was why most people put it into class AB, and sacrificed power.

Brian

[Brian Gaff (Sofa]

The later QLs had a better psu, that did not corrupt microdrives. It was just poor design. you got a transient that could write to a drive even if it was not rotating. Oddly you never had that problem with ZX Spectrum drives.

Brian

[Harry Bloomfield, Esq.]

Brian Gaff (Sofa) presented the following explanation :

I used microdrives, on my own system - a partial design of my own, before Sinclair began using them.

[Harry Bloomfield, Esq.]

The Natural Philosopher formulated on Friday :

Did he bin the usable ones? :-)

[Fredxx]

I used to do the same with LM324s. Simple pullup resistor to the +ve power supply solved the crossover.

[Steve Walker]

While it had an 8-bit bus, it was a full 32-bit processor internally. The Motorola 68008 was basically the same as a Motorola 68000, except for the 8-bit external data bus. The latter being the chip (with a 16 bit external bus) that Apple was using in its Macintoshes at the time. Internally, the full range (including those with 32 bit external buses), were the same.

The biggest restrictions were that it shared the memory with the display, so could not run at full speed without ceding priority to the display whenever both needed to access it and when talking to slower peripherals plugged into the expansion slot, many needed to momentarily slow the processor down to 1MHZ while they interacted.

There are plenty of freely downloadable BASIC interpreters (and compilers) - plus almost any other language people might want to try.

Yes, they did seem to be pretty popular for journalists.

[John Walliker]

Most of the pirate radio stations near London were mobile and used

807 or 813 beam tetrode valves power by rotary converters and lorry batteries.

John

[Max Demian]

I don't think I ever saw one actually being propelled electrically. I saw one being pedalled once, and most days I passed one being hauled on a rope up the hill leading to Beaconsfield. He must have had fun on the way down.

[The Natural Philosopher]

PROPER technology!