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Welcome to the nostalgic history of home and game computers  

home computer for a minimum prize

In 1980 the eccentric Briton Clive Sinclair already made the impossible possible by selling a home computer, the ZX80, for less then 100 British pounds, in 1981 he again hit the headlines. The successor of this tiny white computer, the ZX81, was sold for the amazing price of 70 pounds, or 100 dollar in the United States. Thus the inventor of miniature devices made it possible for hundreds of thousands of people to get acquainted with the world of the computer. About a million ZX81 computers were sold in and outside Europe.

It was clear that the ZX80 was the mother of the ZX81. There weren't tremendous differences, although the ZX81 had some important improvements you could tell even with a minor glance at the photobooks out at the time. The 8 KB ROM (the ZX80 only had 4 KB) contained thirty extra commands of Sinclair's Basic. And the ZX81 could handle floating point numbers, an essential ability the ZX80 lacked.
Besides, it was possible to by-pass the weird ZX80 phenomenon that the display function was shortly switched off when a key was touched. By a Basic command the ZX81 could be brought into a SLOW- or a FAST-mode. In the FAST-mode the ZX81 still had the same flaw as the ZX80, but in the SLOW-mode the CPU could divert it's attention between the output to the screen and other activities. Unlike the CPU's in other home computers, the central processor in the ZX80 and ZX81 also handled the display function.

Clive Sinclair had radically changed the inside of his tiny home computers. Whereas the ZX80 contained 21 chips, in the inside of the ZX81 there were only four - an unbelievable minimum in those years. The reduction was possible because the ZX81 had and Ferranti ULA-chip, that took care for all in- and output.

On the other hand, Sinclair more or less deliberately hadn't solved some flaws from the ZX80. Its successor also had a very awkward membrane keyboard, that turned lengthy typing into a torture.
Opinions were divided on the famous multifunctionality of Sinclair's keyboard. Some people got never used to it, others considered it as very useful. Keys on the ZX81 had up to five functions. But let's be honest: with a better keyboard it had been impossible to sell this home computer for such a low price.

A flaw that also returned in the ZX81 was related to the memory expansion pack that could be plugged into the back of the computer. Even during normal use of the computer the module could start to wobble, which often resulted in a temporary crash of the ZX81 and forced the user to enter his cursed Basic listing again. In the manual Sinclair unashamedly proposed to solve the problem by putting the computer and the expansion pack together with a piece of tape.

Many extensions
While the ZX80 was a bit lonely, for the much more popular ZX81 many different extension options were developed. Manufactures, but also hobbyists themselves, quickly started to develop external keyboards that made typing a far less tiresome activity. And when you also had a memory pack, you suddenly had the disposal of an almost mature home computer.
Later in 1981, Sinclair produced the well-known thermal printer. Also in this device Sinclair had sought the absolute minimum ('a silver toilet-roll burner'), so other manufacturers started to sell alternatives. Memotech for instance developed a Centronics interface by which more common printers could be used.
The amount of extension options that appeared for the ZX81 was almost inexhaustible. The possibilities varied from graphical upgrades to 3.5 inch floppy drives.

Top computer
Actually I already regret the few critical comments I made on the ZX81. In the early eighties Clive Sinclair provided beginning computer users with a nice home computer for an absolute minimum price. For many, particular in Europe, the ZX81 was the first home computer and thus their first contact with a new, amazing world.

Specifications of the Sinclair ZX81

Manufacturer Sinclair Research
Period from March 1981
CPU Zilog Z80A or NEC D780C
Frequency 3,25 MHz
RAM 1 KB (expandable to 56 KB)
Text mode 32 x 24
Graphical mode 64 X 44 (by half characters)
Colours black-and-white
Sound none
I/O tv, cassette, extension port
Price 70 pounds / 100 dollar ready-built
50 pounds / 80 dollar self-assembly kit


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History of Home and Game Computers, by Erik Klooster, the Netherlands

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