PMD 85
Encyclopedia
The PMD 85 was an 8-bit personal computer
produced from 1985 by the companies Tesla
Piešťany
and Bratislava in the former Czechoslovakia
.
They were deployed en masse in schools throughout Slovakia
, while the IQ 151
performed a similar role in Czech part of the country.
PMD 85s were famous for their overheating problems, and were jokingly referred to as "coffee machines".
This computer was produced locally due to a lack of foreign currency
with which to buy systems from the West
. After the fall of socialism
in 1989, production of the PMD 85 was stopped. PMD 85 was not competitive in quality or features compared to foreign PCs available at that time.
The PMD 85-2 was an inspiration for the MAŤO
personal computer, also sold as a self-assembly kit. It had different hardware and very limited compatibility with PMD; its BASIC, memory structure and I/O were almost, but not completely the same, but tape format was different. It was intended as a home computer, but never really caught on.
Later, the Didaktik
Alfa and Beta were produced as more reliable clones.
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
produced from 1985 by the companies Tesla
Tesla (company)
TESLA was a large, state-owned electrotechnical conglomerate in the former Czechoslovakia....
Piešťany
Pieštany
Piešťany is a town in Slovakia. It is located in the western part of the country within the Trnava Region and is the seat of its own district. It is the biggest and best known spa town in Slovakia and has around 30,000 inhabitants.-History:...
and Bratislava in the former Czechoslovakia
Czechoslovakia
Czechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992...
.
They were deployed en masse in schools throughout Slovakia
Slovakia
The Slovak Republic is a landlocked state in Central Europe. It has a population of over five million and an area of about . Slovakia is bordered by the Czech Republic and Austria to the west, Poland to the north, Ukraine to the east and Hungary to the south...
, while the IQ 151
IQ 151
The IQ 151 was a personal computer produced by ZPA Nový Bor in the former Czechoslovakia.It had a Tesla MHB8080A CPU / 2 MHz, 32 KB RAM , 4 KB ROM, with video output and the BASIC programming language as external modules...
performed a similar role in Czech part of the country.
PMD 85s were famous for their overheating problems, and were jokingly referred to as "coffee machines".
This computer was produced locally due to a lack of foreign currency
Currency
In economics, currency refers to a generally accepted medium of exchange. These are usually the coins and banknotes of a particular government, which comprise the physical aspects of a nation's money supply...
with which to buy systems from the West
Western world
The Western world, also known as the West and the Occident , is a term referring to the countries of Western Europe , the countries of the Americas, as well all countries of Northern and Central Europe, Australia and New Zealand...
. After the fall of socialism
Velvet Revolution
The Velvet Revolution or Gentle Revolution was a non-violent revolution in Czechoslovakia that took place from November 17 – December 29, 1989...
in 1989, production of the PMD 85 was stopped. PMD 85 was not competitive in quality or features compared to foreign PCs available at that time.
Specifications
- MHB 8080AIntel 8080The Intel 8080 was the second 8-bit microprocessor designed and manufactured by Intel and was released in April 1974. It was an extended and enhanced variant of the earlier 8008 design, although without binary compatibility...
2.048MHz CPUCentral processing unitThe central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in... - 48 KBKilobyteThe kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...
RAM - 4 KB ROMRead-only memoryRead-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
- System monitorSystem monitorA system monitor is a hardware- or software- based system used to monitor resources and performance in a computer system.Software monitors occur more commonly, sometimes as a part of a widget engine. These monitoring systems are often used to keep track of system resources, such as CPU usage and...
- TapeCompact CassetteThe Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply tape, is a magnetic tape sound recording format. It was designed originally for dictation, but improvements in fidelity led the Compact Cassette to supplant the Stereo 8-track cartridge and reel-to-reel...
utilities - TV output
- 288×256 resolutionDisplay resolutionThe display resolution of a digital television or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is controlled by all different factors in cathode ray tube , flat panel or projection...
- 4 levels of grayscaleGrayscaleIn photography and computing, a grayscale or greyscale digital image is an image in which the value of each pixel is a single sample, that is, it carries only intensity information...
or colours, changeable in 6 pixel wide stripes - tape recorderTape recorderAn audio tape recorder, tape deck, reel-to-reel tape deck, cassette deck or tape machine is an audio storage device that records and plays back sounds, including articulated voices, usually using magnetic tape, either wound on a reel or in a cassette, for storage...
interface - ROM module interface. A ROM module with the BASIC programming language was a standard part of the computer, but there were more ROM modules designed and produced, containing Pascal, LOGO and more.
Variants
- The PMD 85, first version, produced by Tesla Piešťany (author was Roman Kiss), was originally in a whiteWhiteWhite is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be...
-coloured case and later in some other colours. It was more of a prototype and is quite rare today. - The PMD 85, second version, produced by Tesla Bratislava, was known as "the" PMD 85, and sometimes labeled as PMD 85-1. It was made with a dark gray case, and was famous for its keyboardComputer keyboardIn computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
s with extremely tough keys. Alphanumeric keys were evaluated in the moment of a key release. - The PMD 85-2 introduced some improvements in BASIC, some in input routines (for instance, key autorepeat), and a much more ergonomic keyboard (but much less mechanically reliable). Some of the changes caused it to be not completely backward compatible.
- The PMD 85-2A used different hardware, leading to less overheating of the memory chips, an additional 8 KB RAM and more memory for BASIC, but was otherwise compatible with PMD 85-2.
- The PMD 85-2B had 64 KB memory modules instead of 16 KB
- The PMD 85-3 added colour TV output – former versions had colour output only when used with a monitor – and some more hardware changes, including mapping all the address space into RAM, which meant it could be made almost 100% compatible with previous models by loading their ROM in appropriate memory locations. Character encodingCharacter encodingA character encoding system consists of a code that pairs each character from a given repertoire with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the transmission of data through telecommunication networks or storage of text in...
included all Czech and SlovakSlovakiaThe Slovak Republic is a landlocked state in Central Europe. It has a population of over five million and an area of about . Slovakia is bordered by the Czech Republic and Austria to the west, Poland to the north, Ukraine to the east and Hungary to the south...
characters, and a Cyrillic version was also produced.
The PMD 85-2 was an inspiration for the MAŤO
MATO
The Maťo was an 8-bit personal computer produced in the former Czechoslovakia by Štátny majetok Závadka š.p., Závadka nad Hronom. Their primary goal was to produce a personal computer as cheaply as possible, and therefore it was also sold as a self-assembly kit. It was basically modified PMD 85,...
personal computer, also sold as a self-assembly kit. It had different hardware and very limited compatibility with PMD; its BASIC, memory structure and I/O were almost, but not completely the same, but tape format was different. It was intended as a home computer, but never really caught on.
Later, the Didaktik
Didaktik
The Didaktik was a series of home computers based on the Intel 8080 and Zilog Z80 processors produced in former Czechoslovakia.-Didaktik Alfa:Didaktik Alfa was produced in 1986, as a "more professional" clone of PMD 85...
Alfa and Beta were produced as more reliable clones.