--- 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 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 comments: - author: baze (Slovakia) date: Saturday 25th July 2020 text: At one point there was an urban myth that Didaktik Gama had an alternative Cyrillic character set combined with Czech/Slovak diacritic marks. I guess the sentence "It has only latin character set" is meant to convey that this urban legend is not true. Didaktik Gama never had anything other than a regular Latin character set, although it used a bolder font. - author: Kubik date: Wednesday 29th June 2016 text: |- The voltages are +5V and approx +20V - the second voltage isn''t stabilized in power supply and may vary. Didaktik Gama stabilizes it to +12V used for video signal circuitry.\ The memory chips are of various origin. I have seen bulgarian CM8164P, russian KR565RU5G (transcribed from cyrilics), or Samsung KM4164B. I wouldn''t be surprised to see czech MHB4164 in some variants.\ The 16Kb memory chips are different to the ones used in ZX Spectrum. The chips used in Didaktik Gama need just one voltage, 5V. I have seen Fujitsu MB8118, or Intel D2118. - author: Martin date: Friday 13rd December 2013 text: Hello Damian, it is 5V and 12V, not 24V. - author: Damian date: Friday 22nd June 2012 text: Didaktik gamm power supply is +5v and +24v - author: Petr (Czech Republic) date: Wednesday 5th November 2003 text: Hello, I still have this cool machine and now I am working on a connection with a PC for sending a picture from Didaktik & showing it in a window on the PC. Nice time to U all! 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.