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Microdigital TK 85 Teardown

Written By: Vinicius Rodrigues Bellini (and one other contributor)
Published: May 20, 2023
  • Comments: 0
  • Favorites: 0
  • Views: 534

Microdigital TK 85 Teardown

Written By: Vinicius Rodrigues Bellini (and one other contributor)
Published: May 20, 2023
  • Comments: 0
  • Favorites: 0
  • Views: 534

Teardown

TK85 was a <a href=https://www.ifixit.com/"https:////en.wikipedia.org//wiki//ZX81/">ZX81 clone made by <a href=https://www.ifixit.com/"https:////en.wikipedia.org//wiki//Microdigital_Eletronica/">Microdigital Eletr\u00f4nica<\/a>, a computer company located in <a href=https://www.ifixit.com/"https:////en.wikipedia.org//wiki//Brazil/">Brazil."},"subscribed":false,"isFavorite":false,"favoriteCount":0,"isCompleted":false,"completedCount":0,"guideData":{"title":"Microdigital TK 85 Teardown","mainImage":"https:\/\/guide-images.cdn.ifixit.com\/igi\/ahX3pDrD4s33XC3s.140x105","mainImageUrl2x":"https:\/\/guide-images.cdn.ifixit.com\/igi\/ahX3pDrD4s33XC3s.200x150","mainImageUrlFull":"https:\/\/guide-images.cdn.ifixit.com\/igi\/ahX3pDrD4s33XC3s.large","published_date":"May 20, 2023","modified_date":"June 21, 2023","isTeardown":true,"commentCount":0,"viewCounts":{"today":2,"week":13,"month":98,"all":534},"author":{"url":"https:\/\/www.ifixit.com\/User\/4230952\/Vinicius+Rodrigues+Bellini","name":"Vinicius Rodrigues Bellini","image":"https:\/\/guide-images.cdn.ifixit.com\/igi\/epHCrwDIRJVhGTJU.thumbnail","authorCount":2,"historyUrl":"\/Guide\/history\/161276"},"difficulty":3,"difficultyName":"Moderate","timeRequired":"30 minutes","flags":[{"flagid":"GUIDE_USER_CONTRIBUTED","title":"Member-Contributed Guide","text":"An awesome member of our community made this guide. It is not managed by iFixit staff.","privilegeid":1,"icon":"user"}],"mainImageWidth":"140","mainImageHeight":"105","totalTimeIso":"PT1800S","stepCount":7}}">

Introduction

The TK85 was a ZX81 clone made by Microdigital Eletrônica, 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

    • Expansão = Expansion connector 2x23 edge pins.

    • Joystic = Joystic 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 are not demountable.

    • The lower par of the case is just a platic 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 1 other contributor

Vinicius Rodrigues Bellini

Member since: 12/12/22

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