Fix Your Stuff Community Store

Microdigital TK 85 Teardown

Written By: Vinicius Rodrigues Bellini (and 2 other contributors)
Published: May 20, 2023
  • Comments: 1
  • Favorites: 0
  • Views: 813

Microdigital TK 85 Teardown

Written By: Vinicius Rodrigues Bellini (and 2 other contributors)
Published: May 20, 2023
  • Comments: 1
  • Favorites: 0
  • Views: 813

Teardown

Introduction

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

This teardown is not a repair guide. To repair your Desktop PC, use our service manual.

  1. Microdigital TK 85 Teardown, The TK 85 case and connectors: step 1, image 1 of 3 Microdigital TK 85 Teardown, The TK 85 case and connectors: step 1, image 2 of 3 Microdigital TK 85 Teardown, The TK 85 case and connectors: step 1, image 3 of 3

    • 9V DC = Nomo P2 power supply

    • ExpansĂ£o = 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.

    Edit

  2. Microdigital TK 85 Teardown, Inside the TK85: step 2, image 1 of 3 Microdigital TK 85 Teardown, Inside the TK85: step 2, image 2 of 3 Microdigital TK 85 Teardown, Inside the TK85: step 2, image 3 of 3

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

    • Those flat cables are very problematic

    Edit

  3. Microdigital TK 85 Teardown, Keyboard removed: step 3, image 1 of 2 Microdigital TK 85 Teardown, Keyboard removed: step 3, image 2 of 2

    • 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.

    Edit

  5. Microdigital TK 85 Teardown, The circuit board: step 4, image 1 of 2 Microdigital TK 85 Teardown, The circuit board: step 4, image 2 of 2

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

    Edit

  6. Microdigital TK 85 Teardown, Rom and Ram: step 5, image 1 of 2 Microdigital TK 85 Teardown, Rom and Ram: step 5, image 2 of 2

    • 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

    Edit

  7. Microdigital TK 85 Teardown, The RF generator: step 6, image 1 of 3 Microdigital TK 85 Teardown, The RF generator: step 6, image 2 of 3 Microdigital TK 85 Teardown, The RF generator: step 6, image 3 of 3

    • Just a RF Chanel 3 VHF modulator.

    Edit

  8. Microdigital TK 85 Teardown, Microchips identification: step 7, image 1 of 2 Microdigital TK 85 Teardown, Microchips identification: step 7, image 2 of 2

    • 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.

    Edit

Author

with 2 other contributors

Vinicius Rodrigues Bellini

Member since: 12/12/22

956 Reputation

6 Guides authored

Badges: 6

+3 more badges

0 Comments

Add Comment

View Statistics:

Past 24 Hours: 3

Past 7 Days: 14

Past 30 Days: 45

All Time: 813