Engineering: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:

• 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.