Didaktik

TheDidaktikwas a series of8-bithome computersbased on the clones ofIntel 8080andZilog Z80processorsproduced by Didaktik inSkalica,in the formerCzechoslovakia.

Initially the company producedPMD 85compatible machines aimed at schools, then switching to the home market withZX Spectrumclones.

Didaktik's glory diminished with the falling price of the16-bitcomputers, such as theAtariandAmiga,around the middle of the 1990s until it was finally steam-rolled by thePCsoon after. The production of Didaktik computers stopped in the year 1994.

Didaktik Alfa

Didaktik Alfa

Didaktik Alfawas produced in 1986, as a "more professional" clone ofPMD 85.It featured 2.048 MHzIntel 8080CPU, 48KBRAM,8 KBROMwith built-inBASIC,good keyboard (compared with PMD 85), monitor video output (but no TV output) with 288×256 resolution and four possible colours. Despite some changes in ROM, it was mostly compatible with PMD 85.Didaktik Alfa 1was a clone of PMD 85-1,Didaktik Alfa 2of PMD 85-2.

Didaktik Beta

Didaktik Beta

Didaktik Betawas a slightly improved version of previous Didaktik Alfa, having almost identical hardware.Didaktik Alfa and Beta were mostly deployed in schools to replace older PMD 85 computers.

Didaktik Gama

Didaktik Gama

Didaktik Gamawas a ZX Spectrum clone with 80 KB RAM divided into twoswitched32 KB memory banks and 16 KB of slower RAM containing graphical data for video output, while the size of ROM was 16 KB.A peripheral interface with a8255chip was added, providingcentronicsplotter and printer connections and aKempston joystickport.

The case was similar to that of the ZX Spectrum+, a grey or black box inA5size, with a flat plastickeyboardand connectors mounted on the rear side. The Gama uses a standardULAchip made by Ferranti. All games developed for the ZX Spectrum 48K were generallycompatiblewith this computer. Anaudio cassettewas used as data storage and aTVserved as amonitor.It is generally said the Gama was unreachable to buy and there were waiting lists several years long.

Didaktik Gama was produced in three variants: the first,Gama '87,fixed somebugsin the original ZX Spectrum ROM (thus breaking compatibility with some software) and introduced its own bugs effectively inhibiting the use of the second 32 KB memory bank from BASIC.Gama '88fixed the original ZX Spectrum bugs in a more compatible way, and also fixed the memory switching bug. The final and the more compatible model wasGama '89.

The computer was expensive but available on the market and could be purchased in Czechoslovak currency outside specializedTuzexstores, unlike other foreign home computers. Production of Didaktik Gama computers ceased in 1992.

Didaktik M

Didaktik M

TheDidaktik Mintroduced in 1990, was cheaper and simple in design than the Gama. The case was more modern, with anergonomic-like shape and separate arrow keys (however, the keyboard was of poorer quality). Inside there was only 64 KB of total memory (16 KB ROM and 48 KB RAM) which was a disappointment in comparison to the Gama.

The computer was considerably redesigned. Instead of the originalULA,a custom circuit from Russian companyAngstremwas used, giving a square screenaspect ratio,instead of a typical 4:3 rectangle. In addition, the wholeRAMwas implemented by a single set of 64 KB chips, from which only 48 KB were used. There was no difference between fast and slow memory regarding video content. System timings were different to the original ZX Spectrum, which prevented some software from displaying timing dependent visual effects.

There were two separated connectors forjoysticksand one connector for additional hardware, such as a printer interface. Unlike the previous version of Didaktik, these connectors were proprietary, with no compatible peripherals available inCzechoslovakia.Thus, users were forced to develop and produce various homemade interfaces to satisfy their needs.

A 5.25-inch floppy disk drive, called D40, was introduced in 1992 and featured a "Snapshot" (seehibernation) button that stored the current memory contents on diskette. It was then possible to later load this memory image and continue the software from its previous state.

A 3.5-inch floppy disk drive, called D80, was also introduced later in 1992, simultaneously to the release of the Didaktik Kompakt.

Didaktik Kompakt

TheDidaktik Kompaktfrom 1992 was basically a Didaktik M with a built-in 3.5-inch 720 KB floppy drive and a parallel printer port.

External links

• Didaktik computers
• Didaktik computers on old-computers.comArchived2011-06-05 at theWayback Machine
• PCB scans
• A schematic including the inside of the modulator
• Didaktik družstvo Skalica– the website of the company(in Slovak)
• Т34ВГ1– an article in the Russian Wikipedia about the Russian ULA replacement(in Russian)