---
title: Microdigital TK-85
categories:
- Computers
types:
- Home Computer
origins:
- Brazil
years:
- '1983'
cpus:
- Zilog Z80 A
params:
  name: TK-85
  image: /media/museum/photos/microdigital_tk85_system_s2.jpg
  company: /companies/microdigital
  company_name: Microdigital
  specs:
  - label: NAME
    value: TK-85
  - label: MANUFACTURER
    value: Microdigital
  - label: TYPE
    value: Home Computer
  - label: ORIGIN
    value: Brazil
  - label: YEAR
    value: '1983'
  - label: END OF PRODUCTION
    value: Unknown
  - label: BUILT IN LANGUAGE
    value: Improved version of the ZX81 Basic
  - label: KEYBOARD
    value: 40-key QWERTY rubber keyboard with up to 5 function per key
  - label: CPU
    value: Zilog Z80 A
  - label: SPEED
    value: 3.25 MHz
  - label: RAM
    value: 16 KB up to 48 KB
  - label: ROM
    value: 10 KB
  - label: TEXT MODES
    value: 32 columns x 24 lines
  - label: GRAPHIC MODES
    value: 64 x 44 dots
  - label: COLORS
    value: Monochrome
  - label: SIZE / WEIGHT
    value: 23 (W) x 14 (D) x 3 (H) cm / 500g
  - label: I/O PORTS
    value: Expansion port, Tape-recorder, RF video out, Joystick
  - label: BUILT IN MEDIA
    value: None
  - label: PERIPHERALS
    value: Microdigital printer, all ZX81 peripherals
  - label: PRICE
    value: Unknown
  tabs:
  - photos
  - adverts
  - hardware
  - docs
  forum_thread: 950
  photos:
  - title: LARGE VIEW
    subtitle: ''
    text: ''
    image: /media/museum/photos/microdigital_tk85_largesystem_s2.jpg
  - title: SIDE VIEW
    subtitle: ''
    text: ''
    image: /media/museum/photos/microdigital_tk85_system_s3.jpg
  - title: TOP VIEW
    subtitle: ''
    text: The case and keyboard design are very similar to the Sinclair Spectrum's.
    image: /media/museum/photos/microdigital_tk85_topview_s1.jpg
  - title: KEYBOARD CLOSE-UP
    subtitle: ''
    text: ''
    image: /media/museum/photos/microdigital_tk85_keyboardcloseup_s1.jpg
  - title: REAR SIDE
    subtitle: ''
    text: ''
    image: /media/museum/photos/microdigital_tk85_rear_s1.jpg
  - title: POWER SUPPLY UNIT
    subtitle: ''
    text: ''
    image: /media/museum/photos/microdigital_tk85_powersupply_s1.jpg
  adverts:
  - title: 'ADVERT #1'
    subtitle: ''
    text: |-
      From the magazine 'Micro Sistemas' of March 1983

      Thanks to **www.mci.org.br**
    image: /media/museum/pubs/microdigital_tk85_pub_s1.jpg
  hardware:
  - title: MICRODIGITAL JOYSTICKS
    subtitle: ''
    text: ''
    image: /media/museum/hardware/microdigital_tk85_joysticks_s1.jpg
  docs:
  - title: MICRODIGITAL TK-85 BASIC MANUAL (PORTUGUESE)
    url: http://www.datacassete.com.br/uploads/manuais/zx81/tk85.pdf
    cover: /media/museum/docs/couvs/tk85%20basic%20manual.jpg
    text: |-
      [**MICRODIGITAL TK-85 BASIC MANUAL (PORTUGUESE)**](http://www.datacassete.com.br/uploads/manuais/zx81/tk85.pdf)written by Microdigital

       compiled/archived by www.datacassete.com.br\
       type of document : PDF\
       size : 19.6 MB\
       source : [www.datacassete.com.br](http://www.datacassete.com.br)

      **... READ THE ONLINE VERSION BY CLICKING BELOW :**
  oc_id: 976
  source:
    url: https://web.archive.org/web/20230608085718/http://www.old-computers.com/museum/computer.asp?c=976
    date: '2023-06-08'
---

After the **TK80**, [TK82](/museum/microdigital-tk-82/) and **TK83** the TK85 was the last [ZX-81](/museum/sinclair-zx-81/) compatible machine Microdigital produced.

However it wasn't only a simple copy of the ZX-81 but featured several useful enhancements. Its rubber keyboard and case were similar to the Spectrum's and were much more pactical for intensive use. The 10 KB ROM held an improved version of the Sinclair's Basic with strings management and editing facility, as well as some primitive graphic commands.

Several additional routines allowed to record tape programs up to 4200 bits per second, manage a joystick interface and the built-in three-voice sound generator.

Thanks to the TK85, Microdigital started to lead the Brazilian home computer market, front of Sinclair and its US branch, Timex.

Thanks to **Joao Roberto** for most of the pictures and information.