MERA 300 was a Polish-built 8-bit minicomputer family. It was first introduced in 1974 at the

Poznań Poznań () is a city on the River Warta in west-central Poland, within the Greater Poland region. The city is an important cultural and business centre, and one of Poland's most populous regions with many regional customs such as Saint Joh ...

Trade Fair and Exhibition.

History

The MOMIK 8-B (MERA) minicomputer had been designed in Poland in 1973. In 1974 the MERA 300 (MERA ZSM), based on the previous model, was introduced. The same year, at the Poznań International Trade Fair and Exhibition, twelve more models were displayed. MERA 300 was designed by dr. Waldemar Romaniuk and Janusz Popko.

About the family

Family of the MERA 300 systems included: * Data processing systems: MERA 300, 301, 302, 303, 304, 305, 306 * Interactive systems: MERA 342, MERA 344 *

Control systems A control system manages, commands, directs, or regulates the behavior of other devices or systems using control loops. It can range from a single home heating controller using a thermostat controlling a domestic boiler to large industrial c ...

: MERA 362 * Universal and special-purpose systems: MERA 392, MERA 396

System architecture

MERA 300 included the next units: *

Processor Processor may refer to: Computing Hardware * Processor (computing) **Central processing unit (CPU), the hardware within a computer that executes a program *** Microprocessor, a central processing unit contained on a single integrated circuit (I ...

s: MOMIK 8b/100 (250 000 instructions/second)

MERA 300 series architecture

Sets of MERA 300 (MERA 302, MERA 303) included: * Central unit with arithmetical unit * Internal memory of 8000 8-bit

word A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no conse ...

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered ...

is divided into 32-word pages. Instruction memory could be accessed using an

instruction pointer The program counter (PC), commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR), the instruction counter, or just part of the instruction sequencer, is ...

. Data could be addressed using page:word offset. * Single-level interrupt system (32 interrupts), * Channel multiplexer * External peripherals: ** printer ** typewriter ** reader ** control console The MERA 301 used magnetic tapes (PK-1 and PK-2) for data storage with a capacity of 0,5 million characters. The MERA 305 was an extended version with DMA and a four-level interrupt system, with a total of 128 interrupts (4x32).
Hard disk
(licensed CDC 9425 cartridge disk drive), fixed plate and exchangeable cartridge 2.5 megabits (3.125 megabytes) each ,connected via DMA channel * 16-bit control interface used to connect e.g. CAMAC crate controllers The MERA 306 was a more complex, extended version with features including: * Internal memory divided to 4k-word pages, with a maximum of approximately 8, 15, 24 or 32K words of memory * Power-outage protection *

Real-time clock A real-time clock (RTC) is an electronic device (most often in the form of an integrated circuit) that measures the passage of time. Although the term often refers to the devices in personal computers, servers and embedded systems, RTCs are pr ...

(RTC) interface * Hard disk (MERA 9425) In addition to the above, it was possible to attach other devices: *

Monitor Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, West ...

and

keyboard Keyboard may refer to: Text input * Keyboard, part of a typewriter * Computer keyboard ** Keyboard layout, the software control of computer keyboards and their mapping ** Keyboard technology, computer keyboard hardware and firmware Music * Musi ...

* Specialized keyboard * Tape memory * Measuring devices and industrial automation. The computer's machine language consisted of 34 instructions, including arithmetical, logical and control instructions.

Data Input/Output

Data input devices for the MERA 300 series were: * 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) Data output devices: * DT 105 tape puncher with control unit JS-DT 105 * DTK 50 tape and card puncher with control unit JS-DTK 50 Other input/output peripherals: * TELETYPE MODEL 390: ** Printing keyboard input ** Printing data while reading from tape reader ** Printing data while punching tapes * FACIT 384 typewriter *DZM 180 dot printer * ALFA 311/M monitor: ** Display onscreen information ** Displaying keyboard input while recording data on a tape

Usage

* office * collecting data * data processing * engineering computations * measurement controlling * industrial process controlling

Software

* OS RTX Real Time eXecutive program Basic system programs: * Programmable manually from the control console * DDT

bootloader A bootloader, also spelled as boot loader or called boot manager and bootstrap loader, is a computer program that is responsible for booting a computer. When a computer is turned off, its softwareincluding operating systems, application code, an ...

* Standard utilities * MOTIS editor * Software-emulated instructions *

Programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...

s: **

Machine code In computer programming, machine code is any low-level programming language, consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). Each instruction causes the CPU to perform a ve ...

** MOTIS assembler ** BASIC ** FORTRAN It should be mentioned that the MERA 300 RTX was not necessary while the MOTIS assembler ran, as it was able to work without an operating system.

Members of the family

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

Bibliography

# Piotr Misiurewicz, Andrzej Rydzewski, Minikomputer Mera 300. Instrukcja dla użytkownika. Wydawnictwa Politechniki Warszawskiej,

Warszawa Warsaw ( pl, Warszawa, ), officially the Capital City of Warsaw,, abbreviation: ''m.st. Warszawa'' is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland, and its population is officiall ...

1979 r. - Instruction of Minikomputer Mera 300 in Polish

References

{{DEFAULTSORT:Mera 300 Minicomputers 8-bit computers Science and technology in Poland