In Western countries in the early 1980s, there was plenty of choice if you wanted an affordable computer: Apple, Atari, TRS-80, Commodore and Sinclair to name a few. But in communist-ruled Romania, mainly you’d find clones of the British Sinclair ZX Spectrum, an 8-bit computer built around the Zilog Z80A, using a CRT TV as display and a BASIC interpreter as UI. The Cobra was one such Romanian Sinclair clone. However, most people couldn’t afford even that, which lead to hackers building their own versions of the Cobra.
Making these clones was highly illegal. But that didn’t stop students at the Politehnica University of Bucharest. They made them for themselves, family and friends, and even sold them at well under market price. To keep people from building radio transmitters, the Communist government kept electronics prices high. So instead, parts smuggled from factories could be paid for with a pack of cigarettes.
Look inside an old Apple II and you’ll see a sea of chips accomplishing what can be done with only a few today. The Cobra clones looked much the same, but with even more chips. Using whatever they could get their hands on, the students would make 30 chips do the job of an elusive $10 chip. No two computers were necessarily alike. Even the keyboards were hacked together, sometimes using keys designed for mainframe computers but with faults from the molding process. These were cleaned up and new letters put on. The results are awesome hacks which fit right in here on Hackaday.
Sadly though, it often takes harsh necessity to make a culture where these inspiring hacks thrive in the mainstream. Another such country which we’ve reported on this happening in is Cuba, which found the necessity first when the U.S. left Cuba in the 60s and again when the Soviet Union collapsed in the 90s, reducing the availability of many factory produced items needed for daily life, and creating a DIY society.
From the blog of [telmomoya] we found his latest project: a hardware based multicore solution for a ZX Spectrum Emulator. It’s not the first time we feature one of his builds, last year we was working on a ARM Dual-Core Commodore C64. Luckily for Speccy fans, it seems a ZX Spectrum project was just unavoidable.
At its heart is the EduCIAA NXP Board, a Dual Core (M4 & M0) 32-bit microcontroller, based on the NXP LPC4337. It’s an Argentinan-designed microcontroller board, born from an Argentinian academic and industry joint venture. [telmomoya] took advantage of the multicore architecture by running the ZX Spectrum emulator on M4 core and generating the VGA signals with M0 core. This guarantees that the VGA generation, which is rather time-sensitive, remains isolated from emulation and any task running on other core. The VGA sync is via polling and using DMA GPIO the RGB signals can be up to 256 colors. To store the 48 kb VGA frames one AHB32 and one AHB16 memory IC are used.
On the software side, [telmomoya] adopted Aspectrum, a ZX Spectrum Emulator fully written in C, modified to his needs. Overall, the project faced many challenges and issues, like COLOR VGA generation (with GPIO DMA), TFT SPI low fps, Inter Process Communications and bus sharing.
Can you try to name all the games in the demonstration video?
Continue reading “A Multicore ZX Spectrum”
At the end of the 1970s, the 8-bit home computer market had been under way for several years. Companies like Apple and Commodore had produced machines that retain a cult following to this day, and there was plenty for the computer enthusiast to get to grips with. As always though with a new technology, the trouble was that an Apple II or a Commodore Pet wasn’t cheap. If you didn’t have much cash, or you were a young person with uncomprehending or impoverished parents, they were out of reach. You could build a computer from a kit if you were brave or technically competent enough, but otherwise you were out of luck.
As you might imagine, the manufacturers understood that there was an untapped market for cheaper hardware, so as we entered the new decade a range of budget machines that appeared to satisfy that demand. Gone were internal expansion slots, dedicated monitors and mass storage, for cheap keyboards, domestic TV monitors, and home cassette recorders. 1980s teenagers would have computers of their own, their parents safe in the knowledge they were educational while the kids themselves were more interested in the games. Continue reading “A Thoroughly Modern Sinclair ZX80”