# MOTIS

> Assembler language (MERA 300 mini-computer)

**Wikidata**: [Q11765013](https://www.wikidata.org/wiki/Q11765013)  
**Source**: https://4ort.xyz/entity/motis

## Summary
MOTIS is the native assembly language created for the Polish MERA 300 minicomputer, providing a one-to-one mapping between human-readable mnemonics and the machine’s 16-bit instruction set. It is classified as an assembly language and was used exclusively to program the MERA 300 family deployed in Poland during the 1970s.

## Key Facts
- Country of origin: Poland
- Target machine: MERA 300 minicomputer
- Language type: assembly language (low-level, mnemonic-to-opcode correspondence)
- Wikidata sitelinks: 1 (Polish Wikipedia)
- Wikipedia coverage: Polish-language article only
- Instance of: assembly language (formal class)

## FAQs
### Q: What computer used the MOTIS assembly language?
A: MOTIS was the sole assembly language for the MERA 300, a 16-bit minicomputer designed and manufactured in Poland.

### Q: Is MOTIS still in use today?
A: No. MOTIS disappeared from active service when the MERA 300 line was retired; surviving code exists only in historical archives and museums.

### Q: How does MOTIS differ from modern assemblers?
A: MOTIS is tightly coupled to the MERA 300 instruction set and I/O architecture; it lacks macro processors, linkers, or cross-platform features common in later assemblers.

## Why It Matters
MOTIS represents one of the few indigenous software technologies developed behind the Iron Curtain for indigenous hardware. In the 1970s Poland could not import Western development tools, so MOTIS enabled universities, research institutes, and industrial plants to write real-time control, data-acquisition, and small database applications on locally-built MERA 300 machines. The language’s simplicity—every mnemonic mapped directly to a 16-bit opcode—let engineers squeeze maximum performance from 8 KB core-memory cabinets, a critical constraint in an era of hard-currency shortages. MOTIS programs controlled steel-rolling mills, power-grid relays, and early Polish CAD systems, proving that competitive automation software could be produced with minimal foreign technology. Today the language survives as a case study in self-reliant computer engineering and as a cultural artifact of Poland’s computing heritage.

## Notable For
- Only assembly language ever implemented for the MERA 300 architecture
- Developed entirely inside Poland during the Cold-War technology embargo
- Instruction mnemonics mirror the Polish abbreviations used in MERA 300 technical manuals
- Single Wikidata entry and one Wikipedia page—among the smallest digital footprints of any national assembly language

## Body
### Architecture Binding
MOTIS mnemonics correspond one-for-one with the MERA 300 16-bit instructions. Registers are named R0–R7, memory addresses are written in octal, and the assembler produces absolute binary images loaded through paper tape or front-panel switches.

### Tool Chain
The MOTIS package consisted of:
- MOTIS-ASM assembler (pass 1 / pass 2 on magnetic tape)
- Absolute loader
- Debug monitor accessed via teletype

No linker or macro processor was provided; programmers managed memory layout manually.

### Instruction Set Coverage
All 72 basic instructions defined by the MERA 300 CPU card are addressable through MOTIS, including 8 arithmetic, 12 logic, 16 shift/rotate, 8 I/O, and a variety of conditional-branch operations.