Monitors and displays (1)
1980s PC and not-PC displays

In my collection, different PC displays accumulated over time with computers, PCs, sometimes as part sources which have been surprisingly repaired. From simple TV-like displays with green screens, to complex monitors with digital control circuits. Here is a small travel around these. Don't forget to look at some PCs, as they also have monitors to complete a set.

PCs, in their initial form, were designed as office computers for editing text, using databases or calculating data. Such computer doesn't need a sophisticated display - monochrome screen showing letters encoded in a permanent font memory was totally sufficient. The first display card for PC called MDA - Monochrome Display Adapter, was showing text on a green-phosphor small CRT monitor connected by a cable (with separate signal and sync). PC clones used similar monochrome displays. With CGA (Colour Graphics Adapter) boards getting popularity, colour displays were still expensive. More, to display colours the circuit was far different than in colour TV - color information was sent as 4-bit TTL, marking R, G, and B colours as well as bigger or smaller "intensity". This made CGA displays work only with 16 colours. Popularization of higher-resolution raster-based graphics (like Hercules boards) made monochrome monitor manufacturers improve their products. Green CRTs became amber (what was a bit better readable in low-contrast conditions) and later white, imitating inverse-paper display. Hercules made an important step in mid-1980s, it was popular and offered a monochrome, high-resolution (720x350) graphics forcing monitor manufacturers to go up with quality. So the Big Blue shipped displays only for their computer sets, and other manufacturers made their own. Sometimes, when extended capabilities were needed, brecahing the standard. Of course there were displays made especially for some specific PC clones, which had capabilities outstanding MDA or CGA, or just had to be compatible only with these devices. A typical example can be monitor for Siemens PC-D or Robotron EC1834.

ADI DM-14+

Approx. year: 1980s
Type, connector: DB9, MDA/Hercules
CRT: 12", mono, amber screen
A generic Monochrome/Hercules monitor with small amber CRT. Underneath, it has a power switch and two sliders for brightness and contrast. Its power connector is a power supply unit plug for plugging into PC's power supply power output.
According to Commodore Monitors list, the similar monitor (but no power LED in front) was sold ca. 1987 as Commodore DM-14, to PC20/40 PC-compatibles series.

My unit comes from office, where it was used to edit text. It has even menu bar of TAG editor burned in its screen. According to stickers it was bought through German company and then imported to Poland. In 1980s it was a frequent method to buy electronics from the western Europe.


Intra IDM 12HP51T

Approx. year: 1985
Type, connector: DB9, MDA/Hercules
CRT: 12", mono, green screen
This is a really old monitor, made around 1985 in Taiwan by Intra electronics. Its 12-inch green CRT allows to view MDA image. It has a 9-pin connector and brightness/contrast controls in front. It is really simple in construction - it has even transformer-based power supply unit! These displays were common in cheaper and more accessible PC clones from Taiwan.

My unit has been used in a diagnostic instrument. It was operating since manufacturing without interruption, it got retired around 2007. 22 years of usage made its screen very dark and slow-reacting.


 Trimmers and rear.


Warning: There is a later (1987) monitor with the same designation, this is NOT this one. This later one has been also marketed asd INVES and has a nice orange power switch. It was also popular in Taiwanese PC clones.

 Let's see some images from television in 1980s:

Polish Newscast from 1987-04-26 shgowing a CAD using IBM PC with INTRA display.
Polish Newscast from 1987-05-12, 1988-09-05, 1989-04-01, 1989-05-10, our Intra with amber tube.
The last units visible in the media are from 1989 - later colour displays started to be a top-technology in media :).


Approx. year: 1986
Type, connector: DB9, MDA/Hercules
CRT: 12", mono, green screen
A monochrome unit with built-in power supply, for computer or printer. Probably for Olivetti M19 computer. Looks typical for office computer these times.

WARNING: Load the power supply before using. Just connect some old hard disk of car light bulb.

Pinout, looking into connector ( | means flat side of pin):

1  2  X|
X| 3  4
X  5  6|

1 - -12V,
2,3 - +5V,
4, 6 - GND,
5 - +12V 


Siemens WS10 Colour

Approx. year: 1985
Type, connector: DB25 female
CRT: 15" Colour
A very big unknown. This colour display has been used with Siemens WS-10 CAD workstation (see photo below), which was a PC from 1980s. This station has been introduced probably around Siemens PC-X or PC-D as a high-performance version, maybe even having a 286. The pinout of input is unknown. 
from Winkler T. - "Komputerowy zapis konstrukcji", 1989)
My unit doesn't start up, but it may be caused both by failure of circuits as well as their operation (soft-on from CPU?). It was repaired, but some parts are missing - probably previous owner tried to fix it before as values of components are written in chassis.

Hyundai HCM-1421B

Approx. year: 1990
Type, connector: DB9, TTL CGA
CRT: 14" colour
A colour CGA monitor for colour boards, one of the last. This time branded "Hyundai", as many of these lines, with 14-inch nice CRT. Although Korean or Taiwanese, this unit is based on Samsung CRT and Japanese circuits. One more thing: This unit is quite heavy as for early 1990s CRT.


Polkolor MM-14SP

Approx. year: 1990
Type, connector: DB9, TTL
CRT: 12" mono (amber)
See Elwro 801AT for photos. A Polish monitor made by Elwro in small quantities using western semiconductors and tube, Polish passive components (but only some), switches, trimmers and casing. Its production probably had something to do with Schneider cooperation around 1988-1989 which ended quickly.
What's interesting this device is extremely tolerant to input signals - can display many picture types without problems, I connected it into different MDA, CGA, Hercules and EGA variants (by converter) and it always shown something. Usually the first failure is the input filter capacitor, big red one.
In other gallery

Commodore 1402

Approx. year: 1988
Type, connector: DB9, MDA/Hercules
CRT: 12" mono (white)
See Commodore PC10 gallery for photos. This is of courde Hyundai, it was used with Commodore PC series. Commodore haven't used their original monitors for PC series, but purchased from usually Taiwanese companies. This approach was cheaper.

Commodore 1404

Approx. year: 1989
Type, connector: DB9, MDA/Hercules
CRT: 12" mono (amber)
See its description. Definitely Hyundai display, used in early PCs, as well as in some computers which emitted video in TTL standard. It was also used in Commodore PC series.
For the same unit, but branded Hyundai, see next item, Hyundai HMM-1401.

My unit is in a good shape, but has periodic sync problems in Hercules modes. What is interestnig, it doesn't happen in MDA or text mode. I suspect capacitors.


Hyundai HMM-1401

Approx. year: 1990
Type, connector: DB9, MDA/Hercules
CRT: 12" mono (amber)
See California Access CA-286 PC for photos. This is very similar to Commodore 1404 and Commodore is an OEM. It was used with a California Access PC, but was available for many PC clones. Generally the trend was that if a computer is used in DOS, text mode and for simple text editing, the best solution is a monochrome monitor, even in early 1990s.

EMC EM-1412

Approx. year: 1991
Type, connector: DB9, HGC/MDA/CGA
CRT: 12" monochrome (white)
These small monochrome monitors were made probably by Daewoo or Hyundai and sold under different brands as well as with OEM markings. They were used with Taiwanese PC clones imported to Poland in early 1990s, and usualy supported CGA and Hercules resolutions. This display has been used with ComSoft 286 PC until PC failed and it was retired. The monitor works until today, having unusually wide range of frequencies also in a low range, it is extremely useful in my "service shelf".
Its brand - EMC - is unknown to me. There indeed is an EMC (sometimes written as "EMC2") company which had its office in Poland in 1990s, but they haven't used an IBM-like logo at least in second half of 1990s. So this display can be a Taiwanese brand or from some small importer.


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