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---
title: MERA-ELZAB Meritum
categories:
- Computers
types:
- Home Computer
origins:
- Poland
years:
- '1983'
cpus:
- U880D CPU
params:
name: Meritum
company: /companies/mera-elzab
company_name: MERA-ELZAB
specs:
- label: NAME
value: Meritum
- label: MANUFACTURER
value: Mera-Elzab
- label: TYPE
value: Home Computer
- label: ORIGIN
value: Poland
- label: YEAR
value: |-
Model 1 : 1983\
Model 2 : 1985
- label: BUILT IN LANGUAGE
value: Basic
- label: KEYBOARD
value: |-
QWERTY full-stroke keyboard, 57 keys, arrow keys\
NMI, CTRL, SHIFT (x 2), ENTER, CLEAR, BREAK. Two keys are blank
- label: CPU
value: U880D CPU (east-german Z80 clone)
- label: SPEED
value: 2,5 Mhz
- label: RAM
value: |-
Model 1 : 16 KB\
Model 2 : 48 KB (up to 64 KB)
- label: VRAM
value: 1 KB
- label: ROM
value: 14 KB
- label: TEXT MODES
value: 32 chars x 16 rows
- label: GRAPHIC MODES
value: |-
Model 1 : 64 / 32 x 16, 128 x 48\
Model 2 : 64 / 32 x 16 (semigraphic mode), 256 x 192 (4 shades of grey), 512 x 192 (monochrome)
- label: COLORS
value: |-
Model 1: monochrome\
Model 2: at least 4 colors
- label: SOUND
value: 1 channel
- label: SIZE / WEIGHT
value: 37.2 (W) x 23.8 (D) x 7.8 (H) cm
- label: I/O PORTS
value: |-
Power Supply (DIN5), Paralell interface (DB26), Serial Interface (DIN5), Tape-recorder (DIN5, 500 baud)\
Model 2 has an external disk drive connector (DB26)
- label: OS
value: 'Model 2 : MER-DOS, CP/M 2.2'
- label: POWER SUPPLY
value: +5v/2.5A, -5v/0.1A, +12v/0.2A
- label: PRICE
value: 160,000 Zloty (Poland, 1984)
tabs:
- photos
- hardware
- links
photos:
- title: MERITUM MODEL 2
subtitle: ''
text: ''
image: null
- title: LEFT & RIGHT SIDES
subtitle: ''
text: ''
image: null
- title: KEYBOARD CLOSE-UP
subtitle: ''
text: Some keys have both the Latin and Cyrillic letters.
image: null
- title: REAR CONNECTORS
subtitle: ''
text: |-
From left to right :
• Power Supply DIN-5 socket\
• Parallel DB25 connector\
• Serial DIN-5 socket\
• Floppy drive DB25 connector\
• Tape-recorder DIN-5 socket (500 baud).
image: null
- title: ELECTRONICS
subtitle: ''
text: The internal electronics is made of two superimposed cards linked together by three connectors
image: null
- title: BOTTOM CARD
subtitle: ''
text: |-
The bottom card is the main board. East European and Japanese chips are mixed. All the standard logic circuits come from Eastern Europe.There is no RAM chips on this card, although provision is made for them.\
**(1)** Z80 processor, marked '80 CPU'\
**(2)** Character generator 2K ROM chip\
**(3)** Tape recorder leads\
**(4)** 7 x 2K ROM chips, made in Soviet Union. They hold the Basic interpreter\
**(5)** One of the three connectors providing the link between the two cards\
**(6)** The quartz is glued on the card. Notice also the unused Bus connector\
**(7)** NEC 8255 PIA (Programmable Interface Adapter)\
**(8)** Timer and I/O chips coming from Soviet Union
image: null
- title: BOTTOM CARD CLOSE-UP
subtitle: ''
text: Processor and I/O chips.
image: null
- title: ROM BANK
subtitle: ''
text: ''
image: null
- title: TOP CARD
subtitle: ''
text: |-
The top card holds the keyboard circuitry, the floppy drive interface and the RAM chips.\
**(1)** 8 x 4164 chips hold the 64 KB user RAM\
**(2)** A second 8255 PIA provides the floppy drive interface.
image: null
hardware:
- title: 5''1/4 DISK-DRIVES
subtitle: ''
text: Picture courtesy of [Kupa Zlomu](http://212.126.12.126/~mcadam/).
image: null
- title: 5''1/4 DISK-DRIVES
subtitle: ''
text: |-
Another bad picture... :-)
Picture courtesy of [Kawior home pages](http://www.niuniek.republika.pl/kawior/html/speccy.html).
image: null
links:
- title: Dziennik Mi³oœnika Polskich Komputerów
url: http://www.elwro.zafriko.pl/kat/mikrokomputery/mera_elzab_meritum_i
text: This polish museum has some information (in polish) and some pictures
comments:
- author: MCbx (Poland)
date: Tuesday 26th July 2016
text: |-
About these countries, a small correction:\
1\. Floppy disk drives were Hungarian (very high fault rate) and later German. Theoretically they could be Bulgarian, as Bulgaria manufactured FDDs and disks these times. Eastern German 5.25" FDDs were mostly quite nicely working clones of Japanese Teacs.\
2\. Keyboard and case is Polish, as well as some chips made by Unitra CEMI and rarely TOMI. Keyboard is reed switch-based.\
3\. Many Meritum units have K565RU\* memory chips, Soviet, not Bulgarian (has Bulgaria made memory chips these times?). 64K units may have Japanese/western chips as it was easier to get through bureaucracy and buy expensive western parts than to buy dense RAM from SU and slash yourself performing quality control again (Soviet export-grade chips had terrible quality control). Generally in silicon, chips in computers from Eastern block are East German (Z80-land VLSI chips), Polish (TTLs, rarely SRAM) or Soviet (all kinds), in some cases western/Japanese. Rarely Romanian (CMOS).
- author: Grzegorz (Poland)
date: Thursday 6th September 2012
text: '"A Meritum III was released and shown on Poznan fair 1986, but apparently wasn''''t produced." - it''''s not true. I have one. Elwro probably produced about 100 computers. I suppose still exist about 5-6 pcs.'
- author: Marek
date: Saturday 24th September 2011
text: |-
I have this computer with improved ROMs - experimental serial interface based network management software is added and memory is expanded to 64K. Not always Bulgarian - sometimes there were Soviet. I heard about a few ROMs in this computer:\
First one, asks "MEMORY SIZE", it''s the first one.\
Next one, asks "OBSZAR PAO", it''s the most common one.\
My version asks "MEMORY SIZE" and displays "OETO-POL.SL.NET-BASIC" or something like that - it''s an experimental networking system, maybe one shown in technological exhibition in Bulgaria (?Plovdiv?). Network extensions are started by NET command.\
Another version tries to boot from floppy and if it''s impossible jumps to monitor. I don''t know anything about it except I have a photo of it running (from internet auction).
- author: Thomsonicus (Poland)
date: Sunday 27th August 2006
text: This piece of hi-tek computing wasn't really popular/widely spread in Poland. Even in 1983 it was deemed out-of-date and the main decision to produce it was probably because of the ease of constructing it in the communist Poland at that date :( Remember all commie countries were blocked from western technologies those days. Nevertheless certain laws were bent and we had western Z80 with a changed name etc.
- author: szymex_software (Polska)
date: Tuesday 1st February 2005
text: o kurcze... nie mają polskiej stony kodowej ;)
- author: szymex_software (Polska)
date: Tuesday 1st February 2005
text: Kto by pomyślał - całkiem niezły komputerek, ale chyba zawalili sprawę że się u nas zabradzo nie przyjoł.
oc_id: 497
source:
url: https://web.archive.org/web/20230201125733/http://www.old-computers.com/museum/computer.asp?c=497
date: '2023-02-01'
---
This Polish computer was first introduced in fall 1983. As pretty much every sophisticated piece of hardware from the Eastern Block, it was copied from a western computer. The ROM is based on the [TRS-80 model II](/museum/tandy-radio-shack-trs-80-model-ii/), so the Meritum can be considered as a TRS-80 clone. It was mainly used in schools and is considered as the precursor of the polish computing industry as it was the first computer to be produced in Poland.
In fact the Meritum is not entirely Polish but rather a miracle of the eastern block industry : the keyboard and case is polish, disk-drives made in Hungary (some sources say Germany) and memory from Bulgary. 8'' disk-drives are said to be the Robotron K6500 ones...
The keyboard is quite special : left, right and down keys are situated on the right part of the keyboard whereas the up key is placed at the opposite left side !! Quite practical... Much weirder, two keys are blank !!
The Meritum has 64 graphic symbols. The Basic takes 12k of the 14k ROM. It is a Tandy Basic modified to use polish letters (Model 2). Some keyboards have Cyrillic letters for the Soviet union instead of the Latin alphabet. The system uses a U880D microprocessor which is a East-German clone of the Z80.
There are two models, the Meritum model 2 having more memory (48k RAM) and higher resolutions than the model 1. It can be connected to external disk-drives and have a built-in disk controller. It can use polish alphabetical signs and has a parallel port.
The Model 1 which had no graphical resolution (only semi-graphic symbols), no colors, small memory and very high price, was not very popular and was considered obsolete even before being marketed !
A Meritum III was released and shown on Poznan fair 1986, but apparently wasn't produced.
Among planned but never created accesories were: network interfaces ( this was actually produced for the II model ), and a expansion graphics processor that would in these days be called nothing more than a graphics accelerator :) Unfortunately, Mera was forced to suspend the productions of Meritums in favor to computer terminals etc. The whole assembly staff of the Meritum line was five people, and East Germany could not meet the demands for the 5,25" disk drives that were needed for the Meritum II. Meritum was abandoned, as it couldn't compete with private imports of C64 and Atari computers.
If you find some info or know more about the Meritum computers, please mail us.