PMD 85

The PMD 85 is an 8-bit personal computer produced since 1985 by the companies Tesla Piešťany and Tesla Bratislava in the former Czechoslovakia.[1][2][3][4]

PMD 85
PMD 85-1
ManufacturerTesla Piešťany
TypePersonal computer
Release date1985 (1985)
Operating systemBASIC
CPUMHB8080A @ 2.048 MHz
Memory48 KiB RWM, 4 KiB ROM
DisplayTV output or RGB component video; 288×256 resolution; 4-level attribute selectable per 6-pixel-wide areas
RelatedMAŤO, Didaktik Alfa and Beta, Consul 2717

The production was local, due to a lack of foreign currency for purchasing systems from the West.

They were deployed en masse in schools throughout Slovakia,[5] while the IQ 151 performed a similar role in the Czech part of the country. The first Czechoslovak video games were created on the PMD 85 (other platforms were ZX Spectrum and Atari).

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 machined ended in 1990.[21]

Variants
A 1987 Czechoslovak Tesla PMD85-2A with a MHB8080A CPU 2.048 Mhz
  • 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.[7][8][9] It was made with a dark 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,[10][11][12] produced by Tesla Piešťany since 1986,[7] introduced some improvements in BASIC, some in input routines (for instance, key autorepeat), a more ergonomic keyboard (but less mechanically reliable) and also terminal mode. Some of the changes caused it to be not completely backward compatible.
  • The PMD 85-2A,[13] produced by Tesla Bratislava since 1987,[7] used 64 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,[4][14] produced by Tesla Bratislava since 1988,[15][7] added colour TV output. Character encoding included all Czech and Slovak characters, and a Cyrillic version was also produced. System memory was enlarged to 8 KiB and monitor included routines for communication with PMD 32 floppy disk assembly, a ROM integrity test and also "PMD 85-2 compatibility mode" by relocation.

Specifications

See also

References
  1. Bórik (2014). "Intro". PMD 85 Infoserver. Retrieved 2023-03-02.
  2. Schotek (2012). "Martin Schotek a PMD 85". Martin Schotek. Retrieved 2023-03-02.
  3. Chrenko. "Urob si sám PMD-85-1". pmd85.topindex.sk. Retrieved 2023-03-02.
  4. "PMD-85". MCbx Old Computer Collection. Retrieved 2023-03-02.
  5. "PMD-85 Tesla". www.old-computers.com. Retrieved 2023-03-02.
  6. PANTHEON.tech (2018-01-16). "PMD-85 & Personal Computing in Czechoslovakia | PANTHEON.tech". pantheon.tech. Retrieved 2023-03-02.
  7. "8 bity / PMD-85 / Mikropočítač PMD 85". SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1. Retrieved 2023-03-02.
  8. "8 bity / PMD-85 / Mikropočítač PMD 85 / PMD 85". SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům. Retrieved 2023-03-02.
  9. "8 bity / PMD-85 / Mikropočítač PMD 85 / PMD 85-1". SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1. Retrieved 2023-03-02.
  10. "Tesla PMD 85-2". VintageComputer.Gallery. Retrieved 2023-03-02.
  11. "8 bity / PMD-85 / Mikropočítač PMD 85 / PMD 85-2". SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1. Retrieved 2023-03-02.
  12. "8 bity / PMD-85 / Mikropočítač PMD 85 / PMD 85-2 5V RWM". SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1. Retrieved 2023-03-02.
  13. "8 bity / PMD-85 / Mikropočítač PMD 85 / PMD 85-2A". SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1. Retrieved 2023-03-02.
  14. "8 bity / PMD-85 / Mikropočítač PMD 85 / PMD 85-3". SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1. Retrieved 2023-03-02.
  15. "PMD 85-3 Osobny Mikropocitac computer CPU". Computer History Museum.
  16. "8 bity / Klony PMD-85". SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1. Retrieved 2023-03-02.
  17. "Computer's description: Didaktik Alfa 2". 1000BiT. Retrieved 2023-01-17.
  18. "8 bity / Klony PMD-85 / DIDAKTIK ALFA 2" [8 bits / PMD-85 clones / DIDAKTIK ALFA 2]. SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1 (in Czech). Retrieved 2023-01-17.
  19. "8 bity / Klony PMD-85 / DIDAKTIK ALFA" [8 bits / PMD-85 clones / DIDAKTIK ALFA]. SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1 (in Czech). Retrieved 2023-01-17.
  20. "8 bity / Klony PMD-85 / DIDAKTIK BETA" [8 bits / PMD-85 clones / DIDAKTIK BETA]. SAPI.CZ - web věnovaný československým osmibitů, zejména počítačům SAPI-1 (in Czech). Retrieved 2023-01-17.
  21. "Consul 2717 ZBA". www.old-computers.com. Retrieved 2023-03-02.
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