website/content/museum/tesla-pmi-80.md

---
title: Tesla PMI-80
categories:
- Computers
types:
- Home Computer
origins:
- Czechoslovakia
cpus:
- TESLA MHB 8080
params:
  name: PMI-80
  image: /media/museum/photos/tesla_pmi80_system_s2.jpg
  logo: /media/museum/logos/tesla_pmi80_logo1.gif
  company: /companies/tesla
  company_name: Tesla
  specs:
  - label: NAME
    value: PMI-80
  - label: MANUFACTURER
    value: Tesla
  - label: TYPE
    value: Home Computer
  - label: ORIGIN
    value: Czechoslovakia
  - label: BUILT IN LANGUAGE
    value: Machine language hexadecimal monitor
  - label: KEYBOARD
    value: 25 key calculator type - Hexadecimal and function keys
  - label: CPU
    value: TESLA MHB 8080 (Intel 8080 clone)
  - label: SPEED
    value: 1 MHz
  - label: CO-PROCESSOR
    value: None
  - label: RAM
    value: 1 KB
  - label: ROM
    value: 1 KB
  - label: TEXT MODES
    value: 9 digit, 7 segment, diode calculator type
  - label: I/O PORTS
    value: DIN 5-pin Power - DIN 5-pin analog I/O to tape -
  - label: POWER SUPPLY
    value: External power supply unit, +5V / -5V / +12V
  - label: PERIPHERALS
    value: Additional ROM and I/O chip sockets
  tabs:
  - photos
  - adverts
  - connectors
  forum_thread: 990
  photos:
  - title: MAIN BOARD
    subtitle: ''
    text: |-
      **(1)** Tape recorder DIN socket\
      **(2)** MHB 8080 microprocessor\
      **(3)** MH 8228 (Intel 8228 clone) - MicroBus controler, converts CPU signals into I/O, MEM, R/W signals\
      **(4)** MHB 8255 (Intel 8255 clone) - main I/O chip, 3x8-bit I/O channels, 1 channel for user, 2 channels for keyboard & display\
      **(5)** Second optional 8255 offering three additional I/O channels\
      **(6)** ROM chip holding the MONITOR program\
      **(7)**MH 8224 clock generator and MH 3205 memory controller\
      **(8)** Two MHB 2114 (Intel 1k \* 4-bit 2114 clone) RAM chips holding the 1 KB user RAM\
      **(9)** Optional I/O card connectors

      An expansion bus is also located between the microprocessor and the ROM chip.
    image: /media/museum/photos/tesla_pmi80_system_s1.jpg
  - title: COMPLETE SYSTEM
    subtitle: ''
    text: Thanks to **Horymir Marek**
    image: /media/museum/photos/tesla_pmi80_system_s3.jpg
  - title: PMI-80 CASE
    subtitle: ''
    text: ''
    image: /media/museum/photos/tesla_pmi80_case_s1.jpg
  - title: CHIPS CLOSE-UP
    subtitle: ''
    text: |-
      CPU, I/O, ROM and RAM chips.

      Thanks to **Horymir Marek**
    image: /media/museum/photos/tesla_pmi80_boardcloseup_s2.jpg
  - title: KEYBOARD
    subtitle: ''
    text: ''
    image: /media/museum/photos/tesla_pmi80_keyboard_s1.jpg
  - title: DISPLAY
    subtitle: ''
    text: Calculator type diodes display
    image: /media/museum/photos/tesla_pmi80_display_s1.jpg
  - title: 'DISPLAY #2'
    subtitle: ''
    text: |-
      When the computer starts, it displays this message.

      Thanks to **Horymir Marek**
    image: /media/museum/photos/tesla_pmi80_displight_s1.jpg
  - title: PMI-80 LOGO
    subtitle: ''
    text: ''
    image: null
  - title: I/O CARD
    subtitle: ''
    text: This card displays each bit of the data bus. It also has a digital to analog converter which allow 0V to 12V output with 256 steps. The max voltage can be adjusted, between 0 and 12V, thanks to the variable resistor.
    image: /media/museum/photos/tesla_pmi80_iocard_s1.jpg
  - title: MANUALS
    subtitle: ''
    text: |-
      The manuals were actualy a complete course on each chip which make up the computer.

      Thanks to **Horymir Marek**
    image: /media/museum/photos/tesla_pmi80_manuals_s1.jpg
  adverts:
  - title: DIAGRAMS
    subtitle: ''
    text: |-
      PMI-80 diagram located in the case cover.\
      If you are interested in more diagrams of the PMI-80, dowload this zipped file holding three diagrams of the whole system.
    image: /media/museum/pubs/tesla_pmi80_casecover_s1.jpg
  connectors:
  - title: CHIPS ARRANGEMENT
    subtitle: ''
    text: Thanks to **Horymir Marek**
    image: /media/museum/connectors/tesla_pmi80_diagram_s1.jpg
  - title: CPU
    subtitle: ''
    text: Thanks to **Horymir Marek**
    image: /media/museum/connectors/tesla_pmi80_diagram_s2.jpg
  - title: CONNECTORS
    subtitle: ''
    text: Thanks to **Horymir Marek**
    image: /media/museum/connectors/tesla_pmi80_diagram_s3.jpg
  - title: KEYBOARD, TAPE INTERFACE & POWER REGULATION
    subtitle: ''
    text: Thanks to **Horymir Marek**
    image: /media/museum/connectors/tesla_pmi80_diagram_s4.jpg
  oc_id: 1016
  source:
    url: https://web.archive.org/web/20230606190802/http://www.old-computers.com/museum/computer.asp?c=1016
    date: '2023-06-06'
---

The PMI was used for learning programing machine code in Czech and Slovakian polytechnic university from 1982 year.

It was developed and manufactured in Tesla Piestany factory which core business was to produceo active components like diode, transistor and integrated ciruits, including the MHB 8080A CPU and chip from his family.

It was a basic system, enclosed in a plastic case and precisely based on the MHB 8080A, a Tesla version the 8080 processor.

It had minimal ROM, RAM and I/O capabilities, but enough in schools, to enter, study and run small programs.

Thanks to **Jiri Cernohlavek**, from Czech Republic, for information and pictures.

---

**Martin Bruno** remembers:\
I used this computer when I was attending Industrial College Of Electrical Engineering in Eastern Slovakia, town of Michalovce at second class in 1994/95 and this computer was widely used at Slovakian technical schools for learning machine code of 8080 processor.\
It was a bit complicated because you had to write program in hex form. Actually it was computer but practically not for home use nor for some entertainment... it was a good form how to scare people about machine code programming :-)\
I must to thank my home computer [Didaktik M](/museum/didaktik-m/) at that time that I learned machine code resp. assembler in much more comfortable way :-)

**Dan Handenberg** adds:\
The computer was originally designed to control printing machines, but the processing was too slow to transfer information fast enough to the peripherals.

<table> <tr> <td></td> <td>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.</td> <td></td> </tr> </table>