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M > MICRODIGITAL > TK-90X   


Microdigital
TK-90X

The TK90X was the first Sinclair 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

_______________________

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.

ShareThis


 

Hey, is there any other version of the board? I had one of these, and I changed the ROM version and it was running a genuine ZX Spectrum ROM. But funny I don't remember where the hell is the slot... Looking at the pictures, seems to me that in the place that is the I/O chip, it used to be the ROM eprom. Can anybody help me?

          
Tuesday 10th June 2008
Marcelo Santos (Sao Paulo / Brazil)

 

NAME  TK-90X
MANUFACTURER  Microdigital
TYPE  Home Computer
ORIGIN  Brazil
YEAR  1985
BUILT IN LANGUAGE  Sinclair BASIC
KEYBOARD  Rubber keyboard - 40 keys
CPU  Z80A
SPEED  3.58 MHz
RAM  16K and 48K versions
ROM  16 KB
TEXT MODES  32 chars. x 24 lines
GRAPHIC MODES  256 x 192 dots
COLORS  8 with two tones each (normal and bright)
SOUND  1 voice / 10 octaves (via TV set)
SIZE / WEIGHT  Unknown
I/O PORTS  Expansion port, tape-recorder (1200 bauds), RF video out, Joystick
POWER SUPPLY  External 9V DC power supply unit
PERIPHERALS  Sinclair (not all) and third sources peripherals
PRICE  16K Cruzeiros 1.499.000, US$ 214 (1985)
48K Cruzeiros 1.749.000, US$ 249


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