Mera EC7915

Called "Independent monitor", EC-7915 (or 7950) was a complete terminal with Z80 CPU and firmware allowing to do basic things in text buffer. It was made on Swedish licence - in Sweden it was known as Stansaab Alfaskop. It was quite rough construction even in 1980s, as Mera purchased licence in 1976 or 77. 7915 was expensive, but it used no other circuits than simple logic and EPROMs. Later models had 8255 circuit to control keyboard, allowing to drop Keyboard Module. The device used amber CRT, and was complete Z80 system working in modular technology - module for CPU and data processing, module for text output, in earliest models (I don't know if these were made outside Sweden) module for keyboard handling.
These units were used with many computers, starting from Mera 60 RT system up to ComPAN 8 CP/M machine.

Manufacturer: Mera-Elzab

Model EC-7915 (EC-7950)
Year: 198?
CPU: Z80
Memory: 6kB (12x2114 chips)
Display: Monochrome amber CRT
Keyboard: Dedicated Hallotron keyboard.
Main port: RS/232 serial
Additional ports: Printer port
Keyboard port
Internal: System bus expansion
Internal: CRT, LEDs and brightness/contrast trimmers (3 connectors)
Internal: Mainboard power (DB25)

Peripherals in collection:
 - Keyboard - NOT original one, or too much original - from German terminal (also western Mini  Bee Terminal, keyboard manufactured by Micro Switch as SW1139, see schematic), which was used with first units of Mera and abandoned because of rare parts used.



My unit comes from Cracow's waterworks authority. It was used there probably with Mera 60 computer (see picture). As they dismantled the computer, they removed back cover to disconnect keyboard - it's missing.
My unit isn't in good condition - as logic part works perfectly, the display is heavily damaged. Centering rings on CRT are shattered and some CRT circuitry is bad too. As I tried to diagnose it (I don't have a schematic) I figured out that there may be problems with CRT filament voltage or the CRT itself.

Mera-60 was a RT computer system for industrial measurements. It was based on 8080 CPU, battery-backed RAM and had modular construction allowing to install additional interfaces (digital, such as DZM-180 printer interface, 1.8MB 8" floppy disk controllers or digital measurement inputs, counters, static inputs etc.), RAM, EPROMs, paper tape reader/puncher etc.
It was working in Bosman operating environment (it has nothing in common with Bosman 8 CP/M machine!) had built-in text editor, assembler and MacroBasic interpreter.
It had also Logel language (not to be confused with Loglan Pascal-like language invented by the end of 1970 in Warsaw University and implemented in Mera 400 computer), a process modelling language invented in Poland. It was used to program parts of Mera-60/80 system, and resulting binary code was burned to EPROMs of Mera system. If you want to analyse binaries, you can download a few pieces of it here.
The first step in Logel modelling, was to design the model using Logel tools: dependency tables, logic expressions/schemmas and consecutivity diagrams. The program was compiled on JS (Jednolity System - Unified System, not JavaScript!) computers and resulting binary code was punched on paper tape. This tape was fed to Mera 60/80 system, which burned its EPROMS with the code. These EPROMS were used to drive a whole industrial system. There were "single" and "double" cards, "double" ones had twice more 2716 EPROMS and manual switch to switch banks. It allowed to, for example, change supervised process very quickly, which was useful where different shifts manufactured different things on the same production line.

Later terminals had Czechoslovakian keyboard made by Konsul Zbrojovka Brno, which was similar to Alfaskop 3500's. Early units, shipped with Mera 60 or 80, had Polish one, enclosed in case similar to Meritum computer. First ones used Western German keyboards manufactured under American brand Micro Switch and used in some American terminals. Meritum took the casing from it.

After Elzab bought licence to manufacture these units, they became wide-spread across Eastern block countries. Similar units were made in Hungary, in Czechoslovakia (Tesla) and in Soviet Union.

Mera 60
(source: Mera catalogue)

Mera 60
(source: "1000 słów o komputerach i informatyce")

Original Alfaskop
(source: Frigoscandia catalogue)

Picture on the right shows modular-type terminal used with Odra 1305. It's later one, with Zbrojovka keyboard. The printer-keyboard unit is probably D-180KSRE or similar. These "printing terminals" were used with Odra machines and other applications.

(source: Bajtek, 1986)

Source: IKS, 1986 - using mainframe with Mera terminals

Source: IKS, 1987 - Terminal used with Mera 400 computer in Nuclear Physics Institute.

Original Alfaskop units were used in Elwro for testing. You can see them in film "Jak działa komputer" (How the computer works) from 1970s. Here are some images from this film:

Alfaskop displaying OS/360 failure

Alfaskop dumping core after OS/360 crash at boot
(1.8MB 640x480 animated GIF!)

Similar cases were used for comPAN 8 computer, it was produced in small quantity by PAN IT division.

Source: IKS, 1987 - probably comPAN 8 or similar unit in Mera modular casing. Photo from Komputer 87 computer show.

Source: IKS, 1986 - probably comPAN 8 or similar unit in Mera modular casing. Photo from Wilkasy '86 computer clubs meeting.



Internal power connector pinout:

View  from mainboard solder side!

13,12,11,25,24,23 - +5V DC
10,9 - +12V DC
8,7 -  -12V DC
6,5 - +35V DC
4 - "S+5" signal from power supply
3,2,1,14-22 - GND + "SMK" signal from PSU

Links: - picture of an original Alfaskop. - I have NO IDEA what it is. It's in Swedish, I don't speak Swedish, but it looks like an article from one of original Alfaskop creators, who wrote his rememberings with computer industry.