PMD 85

The PMD 85 is an 8-bit

The production was local, due to a lack of foreign currency for purchasing systems from the West.^{[citation needed]}

They were deployed en masse in schools throughout

Several variants were developed (PMD 85-0, PMD 85, PMD 85-2, PMD 85-2A, PMD 85-3), with slightly different specifications and compatibility.[6]^{[7][8][9][10][11][12][13][14][15]}

In 1986 compatible machines were introduced by Didaktik:^[16] Didaktik Alfa 1 (a PMD 85-1 clone) and Didaktik Alfa 2 ( a PMD 85-2 clone).^[17][18][19] Didaktik Beta was a slightly improved Didaktik Alfa, having almost identical hardware.^[20] Didaktik Alfa and Beta were mostly deployed in schools to replace older PMD 85 computers.

After the Velvet Revolution of 1989 the computer market opened. The PMD 85 was not competitive in terms of quality or features to foreign machines and production stopped.

The PMD 85-2 was an inspiration for the MAŤO personal computer, released in 1989 as a self-assembly kit. It had different hardware and very limited compatibility - BASIC, memory structure and I/O were almost similar, but the tape format was different. It was intended as a home computer, but never really caught on.

The same year ZBA, a company from Brno, introduced the Consul 2717, another PMD 85-2 clone, sold to schools.^[21] Production of this machine ended in 1990.^[21]

Variants

• The PMD 85-0, a prototype produced by Tesla Piešťany (author was Roman Kišš),^[6] was originally in a white-coloured case and later in some other colours. It is quite rare today.
• The PMD 85, produced by Tesla Piešťany since 1985, was known as the PMD 85 or PMD 85-1.
  gray
  case, and was known for its keyboards with extremely tough keys. Alphanumeric keys were evaluated at the moment of a key release.
• The PMD 85-2,
  backward compatible
  .
• The PMD 85-2A,
  Kib
  RAM chips instead of 48 Kib, leading to less overheating of the memory chips, resulting in more memory available for BASIC, but was otherwise compatible with PMD 85-2.
• The PMD 85-3,
  relocation
  .

Specifications

• MHz CPU
  (clone of Intel 8080)
• 48
  KiB RAM
  (64 KiB for PMD 85-2A and PMD 85-3 )
• 4 KiB ROM (8 KiB for PMD 85-3)
• System monitor
• Tape
  utilities
• TV output (PAL for the PMD 85-3) or RGB component video
• 288×256 resolution
• 4-level attribute (Black, White, Grey, Blink) selectable per 6-pixel-wide area (8 colors for the PMD-85-3)
• Tape recorder interface
• IRPS interface (passive current loop RS-232 without modem control signals)
• Module interface. A ROM module with the
  LOGO etc. A programmer
  was also available.
• IMS-2 interface (non-standard connector and electrically partially non-conforming) based on MHB8255A
• Two 8-bit parallel buses supporting handshaking (via second MHB8255A)
• Application connector (de facto system
  I/O
  bus)

Picture gallery

• PMD 85-2 Computer
• 
  Top view
• 
  Bottom view
• 
  Inner view of the bottom case
• 
  Main PCB component side.
• 
  Main PCB solder side.
• 
  Main PCB X-Ray view.
• 
  Keyboard PCB component side.
• 
  Keyboard PCB solder side.
• 
  Keyboard PCB X-Ray view.
• 
  I/O PCB component side.
• 
  I/O PCB solder side.
• 
  I/O PCB X-Ray view.

• G-BASIC cartridge
• 
  Top view.
• 
  Bottom view.
• 
  PCB component side.
• 
  PCB solder side.
• 
  PCB X-Ray view.

• PMD 10 Power Supply Unit
• 
  Top view.
• 
  Bottom view.
• 
  PCB component side.
• 
  PCB solder side.
• 
  PCB X-Ray view.

See also

• MAŤO
• Tesla (Czechoslovak company)
• IQ 151
• Didaktik

References

External links

• Tesla PMD-85 Infoserver - Emulator PMD 85 and its clones for Windows
• DJ Martin Schotek's page
• DIY schematic and description