March 26, 2009

Retro Computing, #2 – Sinclair ZX Spectrum

A Spectrum

A Spectrum

Hot on the heels of the ZX81 was the ZX Spectrum – so named because it was now capable of better colour support than its predecessors the ZX80 and ZX81.

The Spectrum was one of the mighty ‘My first computer’ triumvirate of C64, Amstrad and Spectrum that hit the height of their popularity in the 80s. While technically inferior to both the Amstrad CPC range and the Commodore 64, the Spectrum still enjoyed huge success and a massive catalogue of games, including some homebrew games that are still being developed in 2009.
The Spectrum was released in 1982 an initially sported 16KB of RAM, which had become as much as 128KB by the time the final version, the +3 was released in 1987.  Output was by an RF modulator to allow the use of a regular TV as the display (which brought the cost down, compared to the Amstrad CPC which had a proprietary monitor) and input was initially by cassette tape, though floppy drives could be connected and the +3 had the same 3″ drive as the Amstrad CPC 6128 and 664.

The Spectrum held colour as an array, meaning that particular areas of the screen had a particular colour assigned to it. This conserved memory but lead to single colour sprites and colour clashes in arcade style games. Despite this limitation around 18,000 titles (not all of them games) were released for the computer and its hardware limitation meant that designers had to be creative with their programming, leading to games that are very playable.

Thanks to modern emulators available on Windows, Linux and Mac OS, which can recreate the Spectrum hardware in software, there is still a very active homebrew scene which still produces new games, some 28 years after the original launch.

Filed under: retro
Tags: , , , ,
komakino @ 1:02 pm

March 19, 2009

Retro computing – #1, ZX81

Since their conception at the start of the 20th century, few technologies have progressed as much as the computer. The development of first the valve, then the transistor and finally silicon chips have lead to the processing power of computers approximately following Moore’s Law which states that the number of transistors that can be inexpensively placed on a chip will approximately double every 2 years.

In the 1980s computers were starting to become affordable for the average home user and among the most popular were the Sinclair range. The ZX81 was the first home computer of many people who are now around 25 years old and older.

Sinclair ZX81

Sinclair ZX81

The ZX81 was the big brother of the older ZX80 and was released in 1981 (that’s 28 years ago, if you want to feel old :D ). It had a Zilog Z80 processor, like the later Amstrad CPC range, and a wopping 1KB of RAM (try to get your Vista in THAT Microsoft!).

The screen was 32 x 24 characters which lead to some rather blocky graphics, but no one seemed to mind. Several games were released including a version of chess that fit in the 1KB of RAM.

The original price was £49.95 – but that came unassembled: you had to solder the unit together yourself. If you wanted the hard work done for you the price rose to £69.95.

Interestingly the ZX81 didn’t use the ASCII character set but instead used its own proprietary character encoding where 0 was space, 1 – 10 were block graphics and the letters and numbers were represented by other codes.

The ZX81 was eventually replaced by the ZX Spectrum which was capable of much better graphics, including colour, had at least 16KB of RAM and for which hundreds of games were released.

Filed under: retro
Tags: , , ,
komakino @ 1:49 pm

x