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Microdigital TK 85 Teardown

crwdns2935163:0crwdne2935163:0 Vinicius Rodrigues Bellini (crwdns2935087:02crwdne2935087:0)
crwdns2935165:0May 20, 2023crwdne2935165:0
  • crwdns2935167:0crwdne2935167:0 1
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Microdigital TK 85 Teardown

crwdns2935163:0crwdne2935163:0 Vinicius Rodrigues Bellini (crwdns2935087:02crwdne2935087:0)
crwdns2935165:0May 20, 2023crwdne2935165:0
  • crwdns2935167:0crwdne2935167:0 1
  • crwdns2935169:0crwdne2935169:0 0
  • crwdns2935171:0crwdne2935171:0 801

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The TK85 was a ZX81 clone made by Microdigital Eletrônica, a computer company located in Brazil.

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  1. Microdigital TK 85 Teardown, The TK 85 case and connectors: crwdns2935265:01crwdnd2935265:01crwdnd2935265:03crwdne2935265:0 Microdigital TK 85 Teardown, The TK 85 case and connectors: crwdns2935265:01crwdnd2935265:02crwdnd2935265:03crwdne2935265:0 Microdigital TK 85 Teardown, The TK 85 case and connectors: crwdns2935265:01crwdnd2935265:03crwdnd2935265:03crwdne2935265:0

    • 9V DC = Nomo P2 power supply

    • Expansão = Expansion connector 2x23 edge pins.

    • Joystick = Joystick connector DIN-6-07M.

    • Mic = audio output for a datacorder.

    • Ear = Audio input for a datacorder.

    • Video = RF chanel 3 VHF output.

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  2. Microdigital TK 85 Teardown, Inside the TK85: crwdns2935265:02crwdnd2935265:01crwdnd2935265:03crwdne2935265:0 Microdigital TK 85 Teardown, Inside the TK85: crwdns2935265:02crwdnd2935265:02crwdnd2935265:03crwdne2935265:0 Microdigital TK 85 Teardown, Inside the TK85: crwdns2935265:02crwdnd2935265:03crwdnd2935265:03crwdne2935265:0

    • Open it carefully because of the 2 keyboard flat cables.

    • Those flat cables are very problematic

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  3. Microdigital TK 85 Teardown, Keyboard removed: crwdns2935265:03crwdnd2935265:01crwdnd2935265:02crwdne2935265:0 Microdigital TK 85 Teardown, Keyboard removed: crwdns2935265:03crwdnd2935265:02crwdnd2935265:02crwdne2935265:0

    • The upper part of the case is the keyboard, but the keyboard itself is not removable.

    • The lower part of the case is just a plastic part.

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  5. Microdigital TK 85 Teardown, The circuit board: crwdns2935265:04crwdnd2935265:01crwdnd2935265:02crwdne2935265:0 Microdigital TK 85 Teardown, The circuit board: crwdns2935265:04crwdnd2935265:02crwdnd2935265:02crwdne2935265:0

    • The circuit board is a very compact circuit board with dual layer traks.

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  6. Microdigital TK 85 Teardown, Rom and Ram: crwdns2935265:05crwdnd2935265:01crwdnd2935265:02crwdne2935265:0 Microdigital TK 85 Teardown, Rom and Ram: crwdns2935265:05crwdnd2935265:02crwdnd2935265:02crwdne2935265:0

    • MM2716Q-5 => 16Kb Eprom

    • 52164KSF/N => 64kb Rom ? It is a custom Microdigital Rom compatible with the NMC2764.

    • MCM4116BC-15 => 8 x 16,348 bits Ram = 16Kb Ram

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  7. Microdigital TK 85 Teardown, The RF generator: crwdns2935265:06crwdnd2935265:01crwdnd2935265:03crwdne2935265:0 Microdigital TK 85 Teardown, The RF generator: crwdns2935265:06crwdnd2935265:02crwdnd2935265:03crwdne2935265:0 Microdigital TK 85 Teardown, The RF generator: crwdns2935265:06crwdnd2935265:03crwdnd2935265:03crwdne2935265:0

    • Just a RF Chanel 3 VHF modulator.

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  8. Microdigital TK 85 Teardown, Microchips identification: crwdns2935265:07crwdnd2935265:01crwdnd2935265:02crwdne2935265:0 Microdigital TK 85 Teardown, Microchips identification: crwdns2935265:07crwdnd2935265:02crwdnd2935265:02crwdne2935265:0

    • Microprocessor

    • Rom

    • Eprom

    • Ram

    • Oscilator 555. Works as an PWM 5 Volt power supply to the micropocessor.

    • Spare space for an audio integrated circuit. It was never implemented in producion in this model.

    • Voltage regulator 7805

    • Frequency divider = 6,5Mhz used for video and 3,25Mhz used for actual clock.

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crwdns2935293:0crwdnd2935293:02crwdnd2935293:0crwdne2935293:0

Vinicius Rodrigues Bellini

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