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The SAPI-1 was a computer produced in the former Czechoslovakia by Tesla since 1980.

It was designed by Eduard Smutný (hardware) and his brother Tomáš Smutný (software), and based on the Intel 8080/2 MHz clone (and later Z80). The SAPI-86 was also developed as an 8086 clone of the PC.

The SAPI-1 had a modular construction with modules:

  • JPR-1 - processor board based on MHB 8080 processor, 1 KB SRAM, 4 KB ROM modules and 6 IO ports
  • JPR-1Z - processor board based on Z80 processor
  • ARB-1 - bus unit
  • JZS-1 - power supply with rack
  • ANK-1 - non smart, no ergonomic membrane keyboard (compatible with Sinclair ZX-80 and ZX-81)
  • REM-1 - extension board with EPROM and SRAM modules
  • AND-1 - alfanumeric video adapter, 40 columns x 24 rows, black and white with 2 KBytes of video buffer at 3800
  • AND-1A - alfanumeric video adapter, 40 columns x 24 rows, black and white with 2 KBytes of video buffer at E800
  • RAM-1 - board of 32 KB of dynamic RAM
  • DSM-1 - modem and serial interface (based on MHB 1012 UART) used to communication with tape recorder
  • BDK-1 - universal developer board
  • DPP-1 - parallel port board (based on two MHB 8255 chips)
  • DGD-1 - B/W graphic video adapter - requires second monitor, cannot output to monitor connected to AND-1
  • RPD-1 - floppy disk controller, due to its complexity (discrete glue logic) was built on two boards connected by cable. This came very late.


3 versions of SAPI-1 were produced:

  • SAPI-1 ZPS 1 (základní průmyslová sestava - basic industrial set):

integer Micro-Basic was stored in ROM, as well as simple machine code monitor, tape was used as main storage device, using single block recording.

  • SAPI-1 ZPS 2:

MIKOS (mikro kazetový operační systém - micro cassette operating system) with better machine code monitor was stored in ROM, any other programming language was loaded from tape, using blocks of 255 data bytes.

  • SAPI-1 ZPS 3:

ROM contains CP/M booting sequence, CP/M is booting from 8" Shugart floppy disk drives. Position of VideoRAM was moved from 3800 to E800 to allow CP/M running. The "Z" version of SAPI-1 ZPS 3 used Z80 processor clone instead of 8080 clone, video with 64 characters per line instead of 40.


  1. ^ Amatérské rádio B1/1983 - initial JPR-1 information
    Amatérské rádio B2/1983 - JPR-1 detailed description
    Amatérské rádio B6/1985 - JPR-1Z detailed description
    Amatérské rádio B1/1986 - JPR-1Z detailed description completion
    Amatérské rádio - old magazine available on CD-ROM
    SAPI-1 manuals published by Tesla DIZ, Prague, Czechoslovakia