MOS Technology 6502 (1975)

Launched September 1975

Microprocessors were expensive forty years ago. Popular processors such as the Intel 8080 and Motorola 6800 would sell for hundreds of dollars, and these high prices were a significant barrier to the development of low-cost personal computers.

A group of engineers from Motorola, including the pioneering Chuck Peddle had tried to develop a simple low-cost device while at Motorola, but had been rebuffed. Instead, they left the company to join a small firm called MOS Technology, and they set upon developing the MOS Technology 6502 processor instead.

The design philosophy of the 6502 could be summed up in about three words: “keep it simple”. Instead of loading the processor down with extra features, Peddle and his team created a processor that was much less complex than rivals. This meant that it was much cheaper than rivals. And it also meant that it was much faster.

A simpler design was cheaper, because the actual silicon part of the chip was smaller, and this led to fewer flaws during manufacturing and also increased the number of chips that could be produced on one wafer. The result of this was that MOS Technology could sell the 6502 for just $25, a fraction of what rivals were charging.

At this price point, the 6502 became an obvious choice for the many of the microcomputers that emerged in the late 1970s and early 1980s, including the Apple II, Commodore PET and VIC-20, Acorn Atom, BBC Micro and Electron, Atari 400 and 800 plus a variety of lesser-known or now-forgotten computers plus a wide range of embedded systems.

MOS Technology was eventually taken over by Commodore in 1976 and spun out into a separate company again in 1995, although that company was eventually liquidated in 2001.

You might think that an 8-bit processor from the 1970s has very little influence today, but there is a surprising twist to the tale. When the engineers at Acorn in the UK were designing their range of 6502-based computers, they were impressed by the simplicity and speed of the 6502 design. This directly influenced the development of the Acorn ARM processor that was used in their Archimedes computer in the 1980s. So successful was the ARM design, that variants of that processor are now used in millions of devices today. The smartphone or tablet you own today is probably based on an ARM core, which is directly influenced by this 40 year old device.

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DEC VT52 (1975)

Launched September 1975

Think of the exciting end of today’s technological spectrum. You might come up with smartwatches, 4K TV and internet-connected fridges. Now think of the other end. Perhaps you might think about UPS maintenance, Sarbanes-Oxley compliance and replacing the pickup rollers in your laser printer. Well, I am going to talk about computer terminals which most people will think belongs on the less-sexy end of the scale..

..but wait. Go back forty years to September 1975. If you were a grown-up back then, you might be lusting after one of those new-fangled digital watches. But it you were very lucky, then perhaps your employer would buy you something like a Digital Equipment Corporation (DEC) VT52 instead.

If you belong to the generation that puzzles over why the icon for “save” is a floppy disk but you have never seen one, then perhaps an explanation is in order. A computer terminal is a pretty simple device that connects to a bigger computer with many users, sometimes in the same building, sometimes thousands of miles away. Back in the mid-1970s, this sort of thing was the state-of-the-art. That computer would sometimes be somewhere else in the same building, or it could be hundreds or thousands of miles away. To some extent, a terminal was just the ultimate thin client.

When the VT52 was launched in September 1975, it marked a significant transition from really incredibly dumb teletypes to devices that could run something that looked rather more like a modern business application. In other words, it helped to take computing out of the realms of the geeks and put it on people’s desks in the office instead.

OK. If you are of the iPad generation then perhaps your eyes are glazing over, but before the 1970s, the most user-friendly way you could interact with a computer was by using a teletype - basically a printer with a keyboard and a computer interface on the back. Everything you typed got printed out, and every response from the computer was printed out too. These things were connected to a box of 2500 sheets of fanfold paper which would run out from time-to-time. And they were noisy. And they were slow.

Sometime in the late 1960s, somebody had the really good idea of replacing the paper with a cathode ray tube, but although they were quieter and eliminated a lot of dead trees, they were still massively dumb devices. These were called glass teletypes, and essentially they worked in the same way as paper-based ones.

But come the 1970s, not only did we have the Bay City Rollers, but also these horribly dumb devices were becoming just a bit more intelligent, which leads us to the DEC VT52. A product of the Digital Equipment Corporation (aka “Digital” or “DEC”) of Massachusetts, the VT52 and its competitors offered some revolutionary features that would help to define modern computing.

Where a glass teletype simply printed out what it received, a terminal such as the VT52 could do a lot more. The single biggest advance was that the computer could move the cursor around the screen and output whatever it wanted, wherever it wanted. And the more basic things like being able to support both uppercase and lowercase characters at the same time certainly helped.

What this all meant was the computers suddenly became much more interactive. Instead of typing something in and just getting a response, you could create forms for entering data. Or create a spreadsheet. Or edit documents. It was the VT52 and its contemporaries that helped to build recognisably modern applications. Perhaps more importantly of all, it opened the way to quite sophisticated games such as DECWAR and Rogue.

The VT52 itself came in several different versions, including one with a printer that could dump the contents of the screen onto a wet sheet of paper. Lovely. And one key design flaw with the VT52 turned out to be the relatively flat top which ended up being covered with papers and manuals.. which lead to overheating.

Typically paired with a DEC PDP-11 minicomputer, the V52 was widely adapted by other computer systems too. In 1978 the VT52 was replaced by the DEC VT100, which became the standard terminal to emulate even today. DEC was taken over by Compaq in 1998, which itself was taken over by HP in 2002. But the direct descendant of the VT52, the VT520, is still in production today.

Within a few years microcomputers such as the Apple II and Commodore PET had moved the computer away from the control of the IT department and fully onto the user's desk, and for a long time it seemed that "thin clients" would vanish. However, the emergence of the World-Wide Web in the 1990s swung the technology the other way.

These days, 1970s DEC terminals in good condition can sell for hundreds of dollars to collectors, despite being about as useful in modern computing as a chocolate teapot.

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Sinclair Black Watch (1975)

Launched September 1975

These days, a modern smartwatch is a tiny miniaturised computer that keeps us entertained, in touch with contacts and connected with the outside world as well as telling us the time. But, forty years ago manufacturers were struggling even to create a basic digital watch that didn’t cost a fortune.

Forty years ago this month we saw the launch of the Sinclair Black Watch, a low-cost digital watch costing around £25 for an assembled version and £18 for a kit (around £157 / €213 and £133 / €153 at today’s prices). Digital watches were a big thing at the time (they even featured as a running joke in the Hitchhiker’s Guide to the Galaxy), so interest in the Black Watch was high.

The Black Watch (the name was a pun on a famous Scottish regiment) was fundamentally different from a modern digital watch in that it used an LED display rather than the typical LCD display we would see today. LEDs draw a lot more power than an LCD, so it wasn’t possible to keep the display on all the time, instead the user had to press a button underneath the display to make the digits light up.

That might be seen as a minor inconvenience, but there was worse. The battery life was meant to be a year, but in practice it was only a few weeks at best or sometimes even days, and the battery was extremely difficult to replace. The watch was also sensitive to temperature (it ran a different speeds in different seasons) and was sensitive to static electricity. It also had a tendency to fall apart.

Essentially, the Black Watch was not fit to be sold, and the return rate was enormous, to the extent that it nearly bankrupted the company. In the end, Sinclair Radionics was rescued by the government and was eventually split up, although the Sinclair name lived on with Sinclair Research that pioneered low cost home computers in the 1980s.

Black Watches these days are very rare, and you can expect to pay several hundred pounds for one in good condition. In fact, this old Sinclair is about as expensive to buy as the modern all-singing-all-dancing Apple Watch. Or alternatively you can get a modern Casio digital watch for about £20 or so which will actually tell you the time in a reliable fashion.

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