Memotech MTX 512 (MTX512)
The MTX512 (64k, expandable to 512, originally sold for £315) was part of a series of Z80A based computers produced by Memotech.
The other computers in the series were the MTX500 (32k, originally sold for £275) and the RS128 (128k expandable to 768).
These machines had some notable differences from their contempraries. Externally, they were all housed in an alluminium case, which acted as both a heat-sink and RF shielding, not to mention being extremely rugged and visually pleasing.
They all have full size, full travel keyboards, with a reputation for being reliable and feelsome, though after around 27 years, I have to say that mine feels a little rough in it's movement.
Internally, they had a very impressive 32k rom, which included such features as a built in assembler, built-in disassembler/debugger called Panel, a forerunner of HyperCard called Noddy, support in BASIC for windowing, and more hadrware sprites than many contemporary machines of the day.
The computer can accept ROM cartridges housing alternative programming languages, the most popular being tthe very speedy PASCAL from HiSoft.
There was a very expensive peripheral called the FDX system, which added 5.25" floppy disk drives, Winchester hard disks and the CP/M 2.2 operating system. I have never seen one of these myself, and suspect they are extremely rare in working order today.
In benchmark tests the MTX performed better than TRS-80 Model 4, Atari 400 and 800, Commodore 64, and TI 99/4a, though was slower and slightly less accurate than the Acorn BBC Micro.
This test was using a BASIC program, so was not only a test of CPU power, but also of the efficiency of the built in programming language. The performance of machine code programs would quite possibly be different.
Memotech were an Oxfordshire based company, founded in the early 80s, who's first products were ram expansions and other peripherals for the Sinclair ZX81.
They went on to produce the MTX line of computers, the first of which was released in 1983.
These systems were commercially unsuccessful, and the company went into receivership in 1985.
It is generally perceived that poor sales of the MTX series was the cause of the company's demise, but there is more to the story than this.
Memotech were working on a deal to sell 64,000 (red) MTX512 computers, with the very expensive FDX, system to the Russian education system.
As the deal progressed, Memotech borrowed heavily from the banks, and received financial support from the UK government, to put the machines into full production, but then at the last minute, the Russians decided the system was too expensive and pulled out.
Memotech collapsed, financially ruined, and the UK govt, having had its fingers burned, ceased investing in UK computer manufaturing companies.
Possibly the most notable occurrance in the history of the MTX was its appearance in the 80s film Weird Science, where it was used by a pair of teen hackers to break into the Pentagon computer network. (Don't try that one at home kids... the Americans don't like it.)