Mera300

MERA 300 is an 8 bits architecture minicomputer of polish technology. MERA 300 was also used as a name forcontinuous series of this type computer. In 1974 was first time showed on Trade Fair and Exhibition in Poznań.

History

In 1973 in Poland was designed 8 bits minicomputer - MOMIK 8B (MERA). On a base of this minicomputer in 1974 was made MERA 300 (MERA ZSM). In 1974 on International Trade Fair and Exhibition in Poznań were showed 12 models of MERA 300.

About family

Family of MERA 300 systems includes:
* Data processing systems: MERA 300, 301, 302, 303, 304, 305, 306
* Conversations systems (programs ends): MERA 342, MERA 344
* Control-steering system (automatic control): MERA 362
* Universal and single-purpose systems: MERA 392, MERA 396

ystem structure

MERA 300 was created from units below:
* Processors: MOMIK 8b/100, MOMIK 8b/100:250 000 processes/second

et of insides facilities

* For direct work of operator
* For control and conversion
* Specializes
* Outside memory

MERA 300 computer series architecture

Set of MERA 300 (MERA 302, MERA 303) include:
* Central unit with “arytmometr” channel
* Internal memory of 8000 words (1 word=8 bits= nowadays: 1 byte); memory is divided into pages, on each 32 word. Memory of addrssing for instruction include all accessible memory by instruction indicator. Addressing of data consist of two parts: page/word.
* One class of interruptions system (32 interruptions),
* Multiplexers channel
* Outside equipment:
* printer
* typewriter
* reader
* control desktop

MERA 301 used as a medium magnetic tapes PK-1 and PK-2 with capacity of 0,5 million signs.MERA 305 was extended version with direct memory access (DMA) and system of 128 interruptions divided into 4 classes (4X32).MERA 306 was more complex extended version with:
* Internal memory divided into volumes each with capacity of 4k words, what gave possibility to extend memory size for about8,15, 24 or 32 k words (nowadays kB).
* Possibility to use voltage] disappearance system protection
* Possibility to connect Real-time clock (RTC)
* Disk memory usage MERA 9425

There where also possibility to connect other equipment like:
* Monitor and keyboard
* Specialized keyboard
* Tape memory
* Connexion equipment with measurements equipment and industrial automatically machine units. Machine code list of instructions was consisted from 34 positions, which included arithmetical, logical and control instructions.

Entering and bringing out of data

For entering data in microcomputers of MERA 300 series where used:
* Tape reader and CTK 50R card reader with control unit JS-CTK 50
* CT 1001A tape reader with control unit JS-CT 1001
* CT 2000 tape reader with control unit JS-CT 2000

For letting out data where used:
* DT 105 tape punch with control unit JS-DT 105
* DTK 50 tape and card punch with control unit JS-DTK 50

Also where used other inside-outside facilities:
* TELETYPE MODEL 390 which gave possibility to:
** Bringing out data from keyboard with printing
** Bringing out data from tape reader with printing
** Printing of data with tape punching
* FACIT 384 typewriter
* ALFA 311/M monitor, which gave possibility to:
** Project information on a screen
** Bringing out information from keyboard with recording data on a tape.

Usage

* In office
* collecting data
* data processing
* engineers counting
* cooperation and controlling measurement apparatus
* industrial processes controlling

oftware

* OS RTX Real Time eXecutive programBasic system programs:
* DDT start program
* Standards under programs
* MOTIS editor
* Programming languages
* Machine code
* Extra coding instructions implemented by programs
* MOTIS assembler
* BASIC
* FORTRANIt is important that for programmer work on MERA 300 systems Real Time eXecutive program is needed- in MOTIS assembler was self-reliant program, which was able to work without OS.

List of versions

* MERA 300
* MERA 301
* MERA 302
* MERA 303
* MERA 304
* MERA 305
* MERA 306