View source for Mera-Elzab Meritum

[[File:Meritum I and Meritum I model 2 machines (2231620941).jpg|thumb|Meritum I (left) and Meritum I model 2 (right) machines, Unimor monitor.]]
Mera–Elzab '''Meritum''' – a family<ref name="basic_manual">{{Cite book | title = BASIC – Meritum. Podręcznik programowania i użytkowania nr 44990001 | publisher = Zakłady Urządzeń Komputerowych Mera–Elzab |lang=pl|url = http://delibra.bg.polsl.pl/dlibra/docmetadata?id=36348&from=&dirids=1&ver_id=&lp=1&QI=}}</ref> of [[Poland|Polish]] [[Personal computer|personal computers]] based on [[TRS-80]] Model I with BASIC Level II.<ref name="biuletyn_10_1983">{{cite magazine | last1 = Korga | first1 = Zygmunt | last2 = Smoliński | first2 = Andrzej | last3 = Lipowski | first3 = Jacek | last4 = Podsiadło | first4 = Paweł |title = Komputer osobisty(?) - Meritum | magazine = Biuletyn Techniczno-Informacyjny MERA | publisher = Zrzeszenie Producentów Środków Informatyki, Automatyki i Aparatury Pomiarowej "Mera" | issue = 256 | volume = 10 | pages = 3–6 | lang = pl | date = October 1983 | url = http://delibra.bg.polsl.pl/dlibra/publication?id=34111&tab=3 }}</ref><ref name="biuletyn_5_6_1984">{{cite magazine | last = Korga | first = Zygmunt | title = Mikrokomputer osobisty Meritum | magazine = Biuletyn Techniczno-Informacyjny MERA | publisher = Zrzeszenie Producentów Środków Informatyki, Automatyki i Aparatury Pomiarowej "Mera" | issue = 52, 55 | volume = 5, 6 | pages = 3–6 | lang = pl | date = May–June 1984 | issn=0239-6645 | url = http://delibra.bg.polsl.pl/dlibra/publication?id=34201&tab=3}}</ref><ref name="informatyka_1_1985">{{cite magazine | last1 = Chrześcijański | first1 = Zbigniew | last2 = Żebrowski | first2 = Jacek | title = Mikrokomputer Meritum-I | magazine = Informatyka | publisher = Wydawnictwo NOT SIGMA | volume = 1 | pages = 17–18 | issn = 0542-9951 | lang = pl | date = January 1985 | url=http://delibra.bg.polsl.pl/dlibra/publication?id=6210&tab=3}}</ref><ref name="re_5_1985">{{cite magazine | last = Górny | first = Jarosław | title = Mikrokomputer Meritum | magazine = Radioelektronik | publisher = Wydawnictwo NOT SIGMA | issue = 84 | volume = 5 | issn = 0137-6802 | lang = pl | date = May 1985}}</ref><ref name=":0">{{Cite web |title=Meritum - MCbx |url=https://oldcomputer.info/8bit/meritum/index.htm |access-date=2023-03-24 |website=oldcomputer.info}}</ref> Manufactured in the 1980s by Mera–Elzab in cooperation with ITM company.<ref name="biuletyn_10_1983" /><ref name="prospekt_1">{{citation | title = Flyer "Mera-Elzab Meritum" | url = https://polskiekomputery.pl/wp-content/uploads/2017/12/mikrokomputer-meritum-itm-prospekt-2-polskiekomputery-pl-2048x1448.jpg | lang = pl}}</ref><ref name="bajtek_1_1985">{{cite magazine | magazine = Bajtek | publisher = RSW "Prasa-Książka-Ruch" | volume = 1 | pages = 20–21 | issn = 0860-1674 | lang = pl | date = September 1985 | title = Na razie nie widać konkurencji | last = Krupa | first = Krzysztof | url = https://archive.org/details/Bajtek11985}}</ref><ref name="informatyka_10_1984">{{cite magazine | title = Mikroinformatyki coraz więcej | magazine = Informatyka | publisher = Wydawnictwo NOT SIGMA | volume = 10 | page = 25 | issn = 0542-9951 | lang = pl | date = October 1984 | url=http://delibra.bg.polsl.pl/dlibra/docmetadate?id=5718&from=&dirids=1&ver_id=&lp=2&QI=}}</ref>

== History ==
In the late 1970s and early 1980s, there was no small [[microcomputer]] available for the general public in Poland.<ref name="bajtek_1_1985" /> The Polish computer industry was manufacturing only [[mainframe]] systems but not small computers for personal use.

In the 1980s, Mera–Elzab was in the group of 500 largest Polish industrial enterprises and 100 largest exporters. It produced [[computer terminal|terminals]], monitors, and computers, but did not manufacture products for the mass consumer market.<ref name="komputer_3_1986">{{cite magazine|last=Majewski|first=Władysław|title=Oto Meritum|magazine=Komputer|volume=3|pages=14–15|date=June 1986|publisher=Krajowe Wydawnictwo Czasopism RSW "Prasa-Książka-Ruch"|issn=0860-2514|lang=pl}}</ref>

ITM was a small foreign company operating in Poland selling measuring systems. In Poland under the rule of the [[communism|communists]], all companies (including Mera–Elzab) were [[State ownership|state-owned]]. One exception was the companies owned by foreigners, often Polish emigrants.

Design of the Meritum began in 1982.<ref name="bajtek_5_6_1986">{{cite magazine | magazine = Bajtek | publisher = RSW "Prasa-Książka-Ruch" | volume = 5-6 | pages = 5–6 | issn = 0860-1674 | lang = pl | date = September 1985 | title = Swego nie znacie Meritum w Elzabie | last = Wojciechowski | first = Roman}}</ref> It was a time of major economic crisis and [[Martial law in Poland|martial law]] in Poland. Mera–Elzab analyzed existing western small computer systems and the following aspects were taken into account for a new product:<ref name="biuletyn_5_6_1984" />

* System components: [[microprocessor|processor]], peripheral and memory chips must be available in Poland or [[Comecon]].
* TV or a cheap monitor as a display.
* The software in [[read only memory|ROM]] memory.
* Tape recorder as [[mass storage]].
* Possibility to connect existing peripherals (printer, [[punch tape]] reader).

Based on the above assumptions, TRS Model I with [[BASIC]] Level II was selected. It was a computer using a [[Zilog Z80]] processor that could be replaced by the [[U880]] made in [[East Germany]]. Peripheral chips produced in Poland by CEMI factory for the MCY7880 processor ([[Intel 8080]] clone) could be used for both the Z80 and U880. Memory chips were available in the [[Soviet Union]].<ref name="informatyka_1_1985" />

The company expected that due to the price the computer would not be available for individual users. Small businesses were the primary target market, followed by research and education institutions. They expected the computer would be also used as an industrial controller.<ref name="biuletyn_10_1983" />

The fathers of the computer were Zygmunt Korga, later technical director of Mera–Elzab and Paweł Podsiadło, an employee of  ITM company.<ref name="komputer_3_1986" /> They were friends from the time of study at the [[Silesian University of Technology]].

The computer was presented to the public for the first time at the [[Poznań International Fair]] in the autumn of 1983. Production began in the summer of 1984. Preparation for production cost 10 million [[Polish złoty|PLZ]]<ref name="bajtek_5_6_1986" /> which was relatively cheap.

From 1984 to 1986 Mera–Elzab produced 2,500 units.<ref name="bajtek_5_6_1986" /> The maximum production capacity of the plant was 4000 units per year.<ref name="bajtek_1_1985" /> The computer was assembled in one room, where 5 people worked. Production of one computer consumed 20 man–hours.<ref name="bajtek_5_6_1986" /> The computer accounted for 1%<ref name="bajtek_1_1985" /><ref name="bajtek_5_6_1986" /> of the production value and at the best moment no more than 3%.<ref name="komputer_3_1986" />

In 1986 Mera–Elzab sold the licence to [[Elwro]] company and terminated production.<ref name="bajtek_5_6_1986" /><ref name="komputer_12_1987">{{cite magazine|title=Komputeryzujmy się|magazine=Komputer|volume=12|pages=10|date=December 1987|publisher=Krajowe Wydawnictwo Czasopism RSW "Prasa-Książka-Ruch"|issn=0860-2514|lang=pl}}</ref> In 1987 Elwro finished production of Meritum as it started manufacturing its personal computer for schools Elwro 800 Junior.<ref name="komputer_12_1987" />

The reception of the computer was initially positive, it was seen as the first Polish personal computer. Later opinions tend to be critical. The press pointed out technical specification is not impressive, especially lack of graphic mode.<ref name="bajtek_1_1985" /><ref name="komputer_3_1986" /> Besides, TRS-80 was an unknown computer in Poland.<ref name="komputer_3_1986" /> There was no software or technical documentation on the market.<ref name="komputer_3_1986" /> 

The computer never became popular, mostly because of a low number of units produced,<ref name="bajtek_5_6_1986" /> the price and technical specification were not competitive to other products,<ref name="bajtek_1_1985" /> and lack of software and documentation.<ref name="komputer_12_1988">{{cite magazine | title = Komputeryzujmy się "Dlaczego Meritum przegrało z Juniorem" | magazine = Komputer | publisher = Krajowe Wydawnictwo Czasopism RSW "Prasa-Książka-Ruch" | volume = 12 | pages = 12 | lang = pl | date = December 1988| issn = 0860-2514}}</ref> 

=== Comparison with other computers ===
Free market prices in 1986. The average salary in that year was 24,095 PLZ.<ref>{{Cite web|url=https://www.zus.pl/baza-wiedzy/skladki-wskazniki-odsetki/wskazniki/przecietne-wynagrodzenie-w-latach|title=Przeciętne wynagrodzenie od 1950 r.|last=|first=|date=|website=ZUS|access-date=2019-09-22|lang=pl}}</ref>
{| class="wikitable"
!Computer
!Price PLZ
!Release
!RAM KB
!Text mode
!Graphics mode
!Sound channels
|-
|'''Meritum I'''
|103,000<ref name="bajtek_5_6_1986" />
|1983
|48
|64×16
|128×48
|1
|-
|[[ZX81]]
|35,000<ref name="komputer_4_1986">{{cite magazine | title = Giełda | magazine = Komputer | publisher = Krajowe Wydawnictwo Czasopism RSW "Prasa-Książka-Ruch" | volume = 4 | pages = 48 | lang = pl | date = July 1986| issn = 0860-2514}}</ref>
|1981
|1+16
|32×24
|64×48
|0
|-
|[[ZX Spectrum]]
|120,000<ref name="komputer_4_1986" />
|1982
|48
|32×24
|256×192
|1
|-
|[[Atari 8-bit computers|Atari 800XL]]
|95,000<ref name="komputer_4_1986" />
|1983
|64
|40×24
|320×192
|4
|-
|[[Commodore 64]]
|175,000<ref name="komputer_4_1986" />
|1982
|64
|40×25
|320×200
|3
|}

== Meritum I ==
{{Infobox computer
| Photo = Zestaw podstawowy Meritum I.jpg
| Caption = 
| Type = [[Personal computer]]
| Released = {{Start date and age|1983}}
| Discontinued = 
| Processor = [[U880]]
| Memory = 16 or 17&nbsp;KB
| Media = 
| OS = TRS-80 Model I BASIC Level II
| name = Meritum I
| CPUspeed = 2.5&nbsp;MHz
| display = [[Composite video]], 64×16, 32×16 text; 128×48 [[semigraphics]]; monochrome
| caption = Meritum I with monitor. Box on the right is power supply.
| memory card = Cassette Tape
| sound = [[Intel 8253]], 1 channel
}}Based on [[U880]] processor at 2.5&nbsp;MHz. 17 KB<ref name="biuletyn_10_1983" /> of RAM (16 KB of [[dynamic random-access memory|DRAM]]<ref name="informatyka_1_1985" /> and 1 KB [[static random access memory|SRAM]]<ref name="informatyka_1_1985" />); 16 KB version was also available.<ref name="prospekt_1" />
[[File:Meritum BASIC Screenshot.gif|thumb|[[BASIC]] startup screen. [[Level II BASIC|''RADIO SHACK LEVEL II BASIC'']] message replaced to ''MERA ELZAB-ITM  BASIC PC''. Some versions displayed translated <code>MEMORY SIZE</code> as <code>ROZMIAR PAO</code>.]]
14&nbsp;KB of ROM<ref name="re_5_1985" /><ref name="biuletyn_10_1983" /> consisted of 12 KB BASIC. It was slightly modified TRS-80 Model I BASIC Level II. In additional 2&nbsp;KB, [[resident monitor|monitor]] program was stored.<ref name="re_5_1985" /> Content of ROM was provided by ITM company.

Display circuit was similar to TRS-80, it supported 64×16 or 32×16 monochrome text mode<ref name="re_5_1985" /><ref name="biuletyn_10_1983" /> only; low resolution 128×48 graphic mode simulated by [[semigraphics]].<ref name="re_5_1985" /> Character generator resided in separate ROM memory, there was also separate 1&nbsp;KB of video memory.<ref name="re_5_1985" /> Similar to TRS-80 there were no lower case characters.<ref name="basic_manual" /> No Polish-specific characters (ĄĘĆŚÓŃŁŻŹ) on the keyboard and character table.<ref name="basic_manual" />

[[Composite video]] signal available on standard [[DIN connector|DIN socket]]. Due to the lack of a built-in [[RF modulator|TV modulator]], it was not possible to connect directly to the TV.<ref name="informatyka_1_1985" /><ref name="re_5_1985" /> An external TV adapter  working in channels 1–6 was available.<ref name="re_5_1985" />

The computer was equipped with parallel and serial port not compatible with TRS-80 Expansion Interface.

[[Parallel port]] was based on MCY7855 universal [[input/output|I/O]] chip which was Polish clone of [[Intel 8255]].<ref name="re_5_1985" /> It could be used to control industrial processes or other peripherals. Although [[IEEE 1284|Centronics]] printer may be connected, there was no software support for that option in ROM.

Serial port used MCY7851 (clone of [[Intel 8251]]); transmission rates from 95 to 9600 [[baud]] were possible.<ref name="re_5_1985" />

In addition, hardware counter chip [[Intel 8253|8253]] was available. Thanks to this chip the computer could generate sound (1 channel), initially using built-in speaker later using an amplifier in a monitor.

As mass storage, only [[cassette recorder]] can be used. Transmission speed was 500 baud. 
[[File:Meritum charset with Polish letters.png|thumb|Meritum charset with Polish letters]]
At the end of the first year of production, the computer was slightly modified by adding support for Polish characters on the screen, a keyboard with Polish characters and the memory was expanded.<ref name="komputer_3_1986" />
{| class="wikitable"
|+Main components<ref name="biuletyn_5_6_1984" />
!Chip
!Equivalent
!Count
!Description
|-
|U880D
|Z80
|1
|Processor made in East Germany.
|-
|K573RF2
|2716
|7
|2&nbsp;KB EPROM made in USSR.
|-
|K565RU3
|4116
|8
|Dynamic RAM made in USSR.
|-
|2114
|
|4
|Static RAM 1&nbsp;KB + 1&nbsp;KB video RAM.
|-
|MCY7855
|8255
|2
|Universal I/O made in Poland.
|-
|MCY7851
|8251
|1
|Serial port made in Poland.
|-
|8253
|
|1
|Hardware counter.
|}

== Meritum II ==
{{Infobox computer
| Photo = Meritum II komplet.jpg
| Caption = 
| Type = [[Personal computer]]
| Released = {{Start date and age|1985}}
| Discontinued = 
| Processor = [[U880]]
| Memory = 32, 48 or 64&nbsp;KB
| Media = 
| OS = CP/M 2.2, MER-DOS
| name = Meritum II
| CPUspeed = 2.5&nbsp;MHz
| display = Composite video, 64×16, 32×16 text; 128×48 semigraphics; monochrome
| caption = Meritum II with a printer, monitor and floppy disk unit.
| memory card = Floppy disk
| aka = Meritum I model 2
}}Meritum II consists of the '''Meritum I model 2<ref name=":0" />''' computer and an external '''floppy disk unit''' with two 5¼″<ref name="re_5_1985" /><ref name="floppy_manual">{{Cite book |title = Dokumentacja Techniczno–Rozruchowa Stacja Dysków Elastycznych Meritum nr 44290000 |publisher = Zakłady Urządzeń Komputerowych Mera–Elzab| lang = pl}}</ref> drives.

=== Meritum I model 2 ===
The memory has been expanded to 32&nbsp;KB or 48&nbsp;KB.<ref name="re_5_1985" /> In the latter case, 64 KB were mounted but addresses colliding with ROM were not available.<ref name="re_5_1985" /> There were some changes in ROM adding support for disk drive, parallel printer and second timer chip as a [[sound chip|sound generator]] (which was never installed in production units).

A second universal I/O chip 8255 (MCY7855) has been added for communication with the floppy disk unit.<ref name="re_5_1985" />

Version with ROM memory to reduced to 8&nbsp;KB existed. It stored procedures to load the program automatically from disk at startup. The computer could work under the control of [[CP/M]] 2.2 or MER-DOS (compatible with [[TRSDOS]] 2.3). BASIC was provided on a floppy disk.

=== Floppy disk unit ===
Placed in a large 360×192×315 mm housing with a weight of 12.5 kg (with power supply for both devices).<ref name="floppy_manual" />

It was a separate specialized computer based on the Z80 processor @ 2&nbsp;MHz with 2&nbsp;KB EPROM and 1&nbsp;KB RAM.<ref name="floppy_manual" />

As the [[disk controller]], the 8272<ref name="floppy_manual" /> chip was used, which was able to handle single and double density disks.

It was equipped with two 5¼″ drives typically K5600 made in East Germany (users complained about the quality of these drives) with a capacity of about 100&nbsp;KB. But other manufacturers' drives could also be used, eg Bulgarian IZOT 5255E.<ref name="floppy_manual" /> Supported disk capacities are 100&nbsp;KB (single density) or 180&nbsp;KB double density.

The computer was supplied with a diskette with the Disk-BASIC which was an extension of the standard BASIC.<ref name="floppy_manual" />

The 8255 chip was used for communication with the Meritum computer. Data transmission was 250 [[kilobit|kbit]]/s for double density disks or 125&nbsp;kbit/s for single density.<ref name="floppy_manual" /> The computer and the disk unit were connected by a 25–wire cable.<ref name="floppy_manual" />

== Meritum  III ==
{{Infobox computer
| Photo = Meritum 3 (Mera Elzab) - 02.jpg
| Caption = 
| Type = [[Personal computer]]
| Released = 
| Discontinued = 
| Processor = 
| Memory = 
| Media = 
| OS = CP/M
| name = Meritum III
| CPUspeed = 
| display = RGB and Composite video<br>64 or 32×16 text; 128×48 semigraphics<br>512 or 256×192, 4 colors
| caption = 
| memory card = 
| units sold = 100-300 units were manufactured
}}Not mass-produced, only 100 to 300 pre production units were made.<ref name=":0" /> 

The graphic mode was added: monochrome 512×192 or 256×192 (4 colors). 

Additional [[RGB color model|RGB]] signal on separate DIN socket was available.

The second serial port and one joystick [[Atari joystick port|DB9 port]] were added. The keyboard layout was changed.

It could work with Meritum II floppy drive unit.

== Network version ==
In 1985, Mera–Elzab submitted to the Ministry of Education a proposal to create a network version of a computer for Polish schools. In this configuration, the Meritum II computer with a connected disk drive would act as a [[server (computing)|server]], student computers were based on Meritum I.<ref name="bajtek_5_6_1986" />

The network project was developed by scientists from the Computing Center of the [[Silesian University of Technology]].<ref name="komputer_3_1986" />

Finally, the Ministry rejected the offer. [[Elwro 800 Jr|Elwro 800 Junior]] was later selected for schools. The Meritum network variant was not produced, only experimental units were made.


==References==
{{Reflist}}

{{TRS-80 and Tandy computers}}

[[Category:Home computers]]
[[Category:Computer-related introductions in 1984]]
[[Category:Computers designed in Poland]]