--- title: Didaktik Gama categories: - Computers types: - Home Computer origins: - Slovakia years: - '1987' cpus: - Z80A params: name: Gama image: /media/museum/photos/didaktik_gamma_system_1.jpg company: /companies/didaktik company_name: Didaktik specs: - label: NAME value: Gama - label: MANUFACTURER value: Didaktik - label: TYPE value: Home Computer - label: ORIGIN value: Slovakia - label: YEAR value: '1987' - label: END OF PRODUCTION value: Unknown - label: BUILT IN LANGUAGE value: Spectrum BASIC interpreter - label: KEYBOARD value: Full-stroke keyboard, Sinclair style, 40 keys, reset button - label: CPU value: Z80A - label: SPEED value: Unknown - label: RAM value: 80 KB (16 KB + 2 x 32 KB) - label: ROM value: 16 KB - label: TEXT MODES value: 32 columns x 24 lines - label: GRAPHIC MODES value: 256 x 192 dots - label: COLORS value: '8' - label: SOUND value: Beeper (1 voice, 5 octaves) - label: SIZE / WEIGHT value: 27 (W) x 16.5 (D) x 3.6 (H) cm - label: I/O PORTS value: i8255 interface, expansion bus, TV and monitor output, tape-recorder sockets - label: BUILT IN MEDIA value: None - label: POWER SUPPLY value: External PSU - label: PRICE value: 6000,- Kcs (Kès) (1987, Czechoslovakia) tabs: - photos - hardware - links forum_thread: 458 photos: - title: GREY VERSION subtitle: '' text: '' image: /media/museum/photos/didaktik_gama_greysystem_s1.jpg - title: SIDE VIEW subtitle: '' text: '' image: /media/museum/photos/didaktik_gama_greyside_s1.jpg - title: GREY KEYBOARD subtitle: '' text: '' image: /media/museum/photos/didaktik_gama_greykeyboard_s1.jpg - title: BLACK KEYBOARD subtitle: '' text: '' image: /media/museum/photos/didaktik_gamma_keyboard_1.jpg - title: REAR CONNECTORS subtitle: '' text: |- From left to right: • Parallel I/O connector\ • Spectrum compatible I/O Bus connector\ • DIN plug used simultaneously for external power supply and tape recorder connexions\ • Monochrome composite video output\ • TV aerial output. image: /media/museum/photos/didaktik_gama_greyrear_s1.jpg - title: INSIDE EXPLAINED subtitle: '' text: |- **(1)** TV aerial output connector\ **(2)** Monochrome composite monitor output connector\ **(3)** DIN plug used simultaneously for external power supply and tape recorder connexions! (see the P.S.U. picture)\ **(4)** Ferranti ULA chipset (Same as Sinclair original version)\ **(5)** Spectrum compatible I/0 connector\ **(6)** Z80 microprocessor labelled ZILOG\ **(7)** Sinclair Operating System and BASIC interpreter 16 KB ROM\ **(8)** Parallel interface (unusual) connector\ **(9)** 8255 Input/Output dedicated chip\ **(10)** 64 KB japanese RAM chips bank\ **(11)** 16 KB East-European RAM chips bank\ **(12)** Power LED (green), Bank switching LED (red) and reset switch\ **(13)** The keyboard cable is soldered on both sides. It is thus impossible to disconnect the keyboard from the motherboard\ **(14)** TV RF modulator image: /media/museum/photos/didaktik_gamma_inside_1.jpg - title: INSIDE GREY VERSION subtitle: '' text: The desing of the motherboard is slightly different from the black one. image: /media/museum/photos/didaktik_gama_greyinside_s1.jpg - title: FERRANTI ULA CLOSEUP subtitle: '' text: Thanks to Martin Kriz for this picture image: /media/museum/photos/didaktik80_inside.jpg - title: INSIDE CLOSEUP subtitle: '' text: Thanks to Martin Kriz for this picture image: /media/museum/photos/didaktik80_inside_2.jpg - title: THE BOX subtitle: '' text: '' image: /media/museum/photos/didaktik_gama_box_s1.jpg - title: IN ITS BOX subtitle: '' text: Inside its cardoard box, the Gama was enclosed into a white plastic case. image: /media/museum/photos/didaktik_gama_greyplasticbox_s1.jpg - title: USER MANUALS subtitle: '' text: '' image: /media/museum/photos/didaktik_gama_manuals_s1.jpg hardware: - title: JOYSTICK 'MADE IN CZECKOSLOVAQUIA' subtitle: '' text: '' image: /media/museum/hardware/didaktik_joystick_1.jpg links: - title: Clube do TK90X url: http://www.tk90x.com.br text: Brazilian site dedicated to the TK90 and other Microdigital systems - title: Here, you can buy several Didaktik models and peripherals. url: http://www.kompaktservis.cz text: Site in Czech language. Try e-mail - title: Home Computer Museum url: http://www.homecomputer.de/pages/f_sinclair.html text: Stephan has a lot of Spectrum clones with wonderful pictures - title: Sinclair Nostalgia Products url: http://www.algonet.se/~rsm/zx/zxclones.html text: Impressive list of ZX Spectrum clones with useful infos - title: ZX Spectrum in the 21st Century url: http://tarjan.uw.hu/zxclones_en.htm text: Nice review of modern Spectrum clones related: - /museum/didaktik-kompakt - /museum/didaktik-m - /museum/microdigital-tk-90x - /museum/microdigital-tk-95 - /museum/robik - /museum/spica-ines oc_id: 463 source: url: https://web.archive.org/web/20230528105857/http://www.old-computers.com/museum/computer.asp?c=463 date: '2023-05-28' --- This was a Slovak Spectrum clone made by [Didaktik Skalica Ltd](http://www.didaktik.sk/i.html). in communism times (1987). It offered 80 KB RAM. As all Z80A based computers, it was not possible to address more than 64k. So the Gama computers used a bank switching technique, with two 32k additional RAMs. There was even a LED on the case, which indicated if the RAM have been switched or not! The Gama computers had a built-in paralel i8255 interface. They used the original Ferranti ULA and had russian made memory chips. The Gama computers were not fully compatible with the original [Sinclair Spectrum](/museum/sinclair-zx-spectrum/) due to some system variables differences. In fact several models were made. \- The first one was black and, as it was made in 1987, it is often called Gama'87. It had a bank switching bug : if you switched the banks and the RAMTOP variable was above 32768, then the computer simply crashed... \- In 1988, the Gama'88 was launched (grey case). It's main difference is that the bank switching bug was repaired. \- One year later, the Gama'89 (guess why) was released because the '88 model was still quite buggy. Some bugs in ROM were corrected and hardware was a little bit changed, so the compatibility was improved. It has only latin character set and a print routine was implemented in ROM. The Gama'99 was the last and the best model of the Gama serie, it was manufactured up to 1992. --- **Branislav Bekes sent us info and specs for the Gama'89 :**\ CPU Z80A, ROM 16k, RAM 80k bankswitched, graphic mode 256x192 with 8 colors, text mode 32x24. Two bottom lines were reserved for interpreter. Sound 1bit beeper.\ I/O ports : TV OUT, VIDEO OUT, TAPE IN/OUT shared with POWER SUPPLY connector. Expansion slot and 8255 interface. Power supply is external and offers +5V and +12V. **About the Ram switching, Abraham add:**\ The memory banks switching in GAMA was used for "tricks", like enabling on GAMA the AY sounds and music in games designed originally for ZX 128, taking game screenshots, enhancing the copy programs and many more things.