--- title: Microdigital TK-90X categories: - Computers types: - Home Computer origins: - Brazil years: - '1985' cpus: - Z80A params: name: TK-90X image: /media/museum/photos/microdigital_tk90_system350_1.jpg logo: /media/museum/logos/microdigital_tk90x_logo_2.gif company: /companies/microdigital company_name: Microdigital specs: - label: NAME value: TK-90X - label: MANUFACTURER value: Microdigital - label: TYPE value: Home Computer - label: ORIGIN value: Brazil - label: YEAR value: '1985' - label: BUILT IN LANGUAGE value: Sinclair BASIC - label: KEYBOARD value: Rubber keyboard - 40 keys - label: CPU value: Z80A - label: SPEED value: 3.58 MHz - label: RAM value: 16K and 48K versions - label: ROM value: 16 KB - label: TEXT MODES value: 32 chars. x 24 lines - label: GRAPHIC MODES value: 256 x 192 dots - label: COLORS value: 8 with two tones each (normal and bright) - label: SOUND value: 1 voice / 10 octaves (via TV set) - label: SIZE / WEIGHT value: Unknown - label: I/O PORTS value: Expansion port, tape-recorder (1200 bauds), RF video out, Joystick - label: POWER SUPPLY value: External 9V DC power supply unit - label: PERIPHERALS value: Sinclair (not all) and third sources peripherals - label: PRICE value: |- 16K Cruzeiros 1.499.000, US$ 214 (1985)\ 48K Cruzeiros 1.749.000, US$ 249 tabs: - photos - links forum_thread: 921 photos: - title: TK90X subtitle: '' text: thanks to Thomas Conté for this picture image: /media/museum/photos/microdigital_tk90x_thomas-conte_1.jpg - title: TOP subtitle: '' text: '' image: /media/museum/photos/microdigital_tk90_system450_1.jpg - title: 'KEYBOARD CLOSE-UP #1' subtitle: '' text: '' image: /media/museum/photos/microdigital_tk90_keybcloseup_1.jpg - title: 'KEYBOARD CLOSE-UP #2' subtitle: '' text: '' image: /media/museum/photos/microdigital_tk90_keybcloseup_2.jpg - title: 'CLOSE-UP #3' subtitle: '' text: Thomas Conté image: /media/museum/photos/microdigital_tk90x_closeup_1.jpg - title: KEYBOARD PARTS subtitle: '' text: the keyboard is made of a sheet of rubber including all the keys, placed onto a printed circuit. When a key is pressed, a small conductive washer located below each key touches the circuit board and connects two tracks. image: /media/museum/photos/microdigital_tk90_keybparts.jpg - title: REAR SIDE subtitle: '' text: |- From left to right:\ • DC power connector\ • Expansion connector\ • 9-pin joystick connector\ • Tape recorder In/Out jacks\ • RF video output to TV set image: /media/museum/photos/microdigital_tk90_back_1.jpg - title: CONNECTORS CLOSE-UP subtitle: '' text: thanks to Thomas Conté for this picture image: /media/museum/photos/microdigital_tk90x_rear_2.jpg - title: BOTTOM SIDE LABELS subtitle: '' text: '' image: /media/museum/photos/microdigital_tk90_labels_1.jpg - title: MAIN BOARD subtitle: '' text: |- **(1)** RF modulator and chinch jack\ **(2)** Tape recorder In/Out jacks\ **(3)** Joystick DB9 plug\ **(4)** Extension connector\ **(5)** 5V DC power regulator\ **(6)** External 9V DC jack\ **(7)** I/O chip\ **(8)** Keyboard connector\ **(9)** Zilog Z80A processor\ **(10)** Seems to be a copy a the Spectrum ULA custom chip (more info needed!)\ **(11)** 48 KB RAM chips. The RAM chips are separated in two banks, 16KB in 8x4116 chips shared with video on a separated bus (framed) and 32KB in 4x4416 chips (right side of the frame) image: /media/museum/photos/microdigital_tk90_mainboard_1.jpg - title: MAIN BOARD CLOSE-UP subtitle: '' text: Custom chip and Z80A processor. image: /media/museum/photos/microdigital_tk90_mainboard_2.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-gama - /museum/didaktik-kompakt - /museum/didaktik-m - /museum/microdigital-tk-95 - /museum/robik - /museum/spica-ines oc_id: 945 source: url: https://web.archive.org/web/20230618221029/http://www.old-computers.com/museum/computer.asp?c=945 date: '2023-06-18' --- The TK90X was the first [Sinclair Spectrum](/museum/sinclair-zx-spectrum/) clone produced by Microdigital. At the time, a special Brazilian regulation allowed local industry to produce and sell copies of foreign computers only to domestic market, however Microdigital computers were also sold in several south American countries. Despite the case was quite the same as the original Spectrum, the TK90 wasn't fully compatible with it because of some additions to the software in ROM (User Defined Graphics editor, TRACE function, error messages in portuguese), and also some differences in I/O ports configuration and addresses. As a result a few games couldn't run on the TK90X, and some Sinclair peripherals could not be used. The TK90X met a large success in Brazil thanks to a vast amount of pirated copies of Spectrum games available in the country. Microdigital announced a **Microdrive clone** but it was never released. However, four other small companies (C.A.S., C.B.I., Syncron and Arcadia) released floppy disk drive interfaces. All interfaces were BetaDisk compatible. Except for the C.A.S. interface, all models had a built-in parallel printer interface.\ Other famous and very popular peripheral was the **Multiface 1** interface. Most brazillian M1's were produced by C.A.S. One year later, Microdigital launched an improved version, the [TK-95](/museum/microdigital-tk-95/) --- **Martin Revert** reports to us:\ In Argentina, it was possible to contact "pirate reverse engineers" who sold games adapted for the TK-90. They knew the Z80 assembler very well and also had a map with the ROM differences between the Spectrum and TK-90.\ I bought some games that worked fine in original Spectrum but not in TK-90. One example was Batman from the Ocean company. 3 weeks after the official release I've got the TK version running smoothly.\ I heard from them that the major problem was a NMI (Non Maskable Interruption). Aparently that thing was liberated in TK-90 and not in the Spectrum.\ The proliferation of Spectrum software piracy in South America have two explanations: The lack of distribution of official games and the strong presence of the Commodore 64 in the market. Thanks to **Sebastian Rho** for all the pictures.
We need more info about this computer ! If you designed, used, or have more info about this system, please send us pictures or anything you might find useful.