title: SAPI-1
text: # SAPI-1
  
  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 (comparable 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:
  
  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.
  
  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.
  
  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.
  
  