Owing a piece of computer history: PRAVETZ 8D – ORIC ATMOS retro vintage computers


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Oric was the name used by the Tangerine Computer Systems in UK for a series of home computer.

As you can see from the company name they were inspired by the very successful Apple Computer 🙂

Tangerine first released Oric-1 in 1983 and after they sold 160 000 pcs in UK and 50 000 in France they made Oric-Atmos in 1984 which was much improved version with better keyboard and more memory (48KB of RAM).

Oric-Atmos was a bit more sophisticated than Apple ][ as it had GI8912 programmable sound generator.

Oric-Atmos inspired lot of clones, one of them was Pravetz-8D, produced in Bulgaria from 1985 to 1991.

Pravetz computers were Bulgarian personal computers brand. They were designed by Ivan Marangozov in ITKR (Institute for Technical Cybernetics and Robotics) which was part of Bulgarian Academy of Science.

First computer designed by ITKR was IMKO2 in 1980 an Apple ][ clone with Mostek 6502 at 1Mhz processor, the processor was also cloned and produced in Bulgaria under the name CM630.

These computers were great success and good opportunity to export them to all around Ex-communist economy zone. Statistics says that in the period 1980-1990 around 40% of all computers sold in ex-communist countries in Eastern Europe were made in Bulgaria.

Pravetz computers had several modifications:

  • Pravetz-8M – dual processor computer with both 6502 and Z80A which could be selected by motherboard jumper so you could run Apple DOS or CP-M on same computer
  • Pravetz-8E – upgrade of original Pravetz-82 with more RAM memory (E=extended memory)
  • Pravetz-8A – based on CM630 with up to 1MB RAM divided in 64KB memory banks
  • Pravetz 8С – cut down Pravetz-8А version, 128Kb RAM integrated, but not expandable, less number of slots, integrated Centronics, FDD controllers, Joystick and sometimes RS-232.
  • Pravetz 8S – 128Kb RAM integrated, exapandable to 1080KB, less number of slots, integrated Centronics, FDD controllers, Joystick and sometimes RS-232. Could control 3.5″ floppy disk drive and a 5MB HDD.

as you can see ITKR did not blindly copy the Apple computers, but also improved the hardware, there were also team of software developers which had released lot of system software including DOS, compilers etc which support Cyrillic alphabet, also talking program which add voice to Pravetz and many other originally developed software.

The major problem with Pravetz 82 and etc to become real home computer was it price, the computer with the special monitor cost about 1600-1800 Bulgarian Leva which was about 6 average salaries at that time and not many people could afford to have at home.

This was changed with Pravetz-8D which was copy of Oric-Atmos and could connect to any normal TV and was with sale price only 420 Leva. This is why many students at that time had Pravetz-8D as their first computer.

The production of Pravetz-8D started in 1985 (!) i.e. it was cloned one year after Tangerine released it to the market.

Initially Pravetz-8D had no floppy interface but only cassette interface, but later Borislav Zahariev wrote DOS-8D operating system and there were lot of amateur hacks how to attach floppy disk from Apple ][ / Pravetz-82 to Pravetz-8D. Borislav also was famous at that time with his text to speech program for Pravetz which was performing pretty well for that time.  Checking where Borislav is now found it in Linkedin http://ca.linkedin.com/in/borislavzahariev  seems he is now in Canada and working for local company and enjoying playing guitar in his free time http://www.youtube.com/watch?v=3Jsap__e8sA .

I’m still keeping my Pravetz-8D and recently I bought on e-bay the original Oric-Atmos, so there they are:

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at left side is Oric-Atmos at right side is Pravetz-8D

As you can see Pravetz-8D is bit bigger but have integrated power supply inside, while Oric need external power adapter.

Let’s see what is under the box in Pravetz-8D:

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In the upper left corner is the RF TV modulator, then the composite video output, cassete interface, parallel port/printer interface and phone modem interface. The power supply is inside the box with large aluminum heatsink.

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here is side view of the connectors

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on the back we can see the year of manufacture 1986 and serial number 03163.

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the keyboard is on separate board with ribbon cable connected to main board.

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Oric-Atmos is with very compact size as power supply is with external adapter. This way UK company makes it easy to export to European countries which use different style of power supply plugs.

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to open it I had to remove the warranty label 🙂

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this is the main board assembly

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the keyboard is on separate board again connected with ribbon cable:

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side view show TV connector, then composite video, cassete interface modem connector (hiden with red tape for some reason) and the parallel printer port and power supply adapter.

Both computers although at 27 years age are still in working condition and in good order 🙂 I have still some cassetes with retro games which run on both

With the years I collected a lot of vintage computers from 1980s and next week will show you something else from my collection.

16 Comments (+add yours?)

  1. josealun
    Jun 24, 2013 @ 17:36:03

    Loved this!Eagerly awaiting your next entries. I really like the unknown (for me) eastern retro computer scene

    Reply

  2. cybor808
    Jun 24, 2013 @ 21:10:56

    Very interesting read, I’m also a collector of 8-bit home computers and consoles, never heard of the Pravetz, Has a nice design some sort of cross between apple II and the latter commodore 64 model.

    Reply

  3. loller
    Jun 25, 2013 @ 11:08:58

    Wow, 555 series Soviet IC’s.

    Reply

  4. Max
    Jun 25, 2013 @ 13:18:09

    Still have my CIP03 Spectrum clone, but I haven’t fired it up in a long time… some really, really fond memories there. They were of course running on the Romanian-made MMN80 (Z80 clone) processor, much the same way as the Pravetz did with the CM630. Back then it seemed like everyone (and their uncle) was doing 8-bit micros – we had the mentioned CIP series, the HC series, the TIM-S, the Prae…

    Reply

    • OLIMEX Ltd
      Jun 25, 2013 @ 14:53:10

      would be cool if you can post some info about it 🙂

      Reply

      • Max
        Jul 02, 2013 @ 11:57:16

        Sure, what would you like to know? 🙂 A general description of the specs can be found here: http://ro.wikipedia.org/wiki/CIP .

        It was a pretty straightforward clone, with the distinction that the first versions had no BASIC in ROM (but did have 64KB of RAM), therefore one HAD to load BASIC from tape after every power-on. The version I had (03) already had ROM-based BASIC (so thankfully no loading from tape all the time), but kept the 64KB RAM which allowed an awesome trick – while one could READ the ROM, one could WRITE the section of RAM behind it – and by switching a specific D-flip-flop on a specific I/O, the ROM could be switched out, so now the RAM was being read.

        Imagine the cool stuff one could do after realizing that the OS could basically be rewritten as desired… One of the first things I did was fix the known broken Spectrum NMI handler, and rig up a POKE-injector to it. The workflow was basically: load OS modifier from tape, enter value(s) of RAM locations you wish to poke (=infinite lives etc.), reset, load the game you want to play, then whenever necessary, push the button rigged to the NMI signal on the extension connector – instant POKE! 😉

        Another quite useful application for this was a memory dumper – load anything from tape, push the button – the running software would freeze up, the NMI handler would kick in and dump the upper 48K of RAM out a parallel cable going to a PC LPT port, on which a Turbo Pascal program saved all of it as a Spectrum emulator dump image – loaded back in the emulator, the software sprung right back to life and resumed running as if nothing happened. What can I say – good times…

  5. Lincoln R.
    Aug 26, 2013 @ 07:46:12

    It’s interesting to see so many US brand ICs in the Pravetz and so few Soviet clones. Also interesting that the ULA has the same markings on it. Did the makers of the Pravetz 8D actually license some technology from Oric?

    Reply

  6. Andrew
    May 18, 2015 @ 02:30:34

    I had an Oric – not the Atmos but the earlier Oric-1 (yes, with the horrid clicky keyboard) and I still have it.

    Re title: Don’t you mean “Owning…” a piece of Computer History?

    Reply

  7. Andrew
    May 18, 2015 @ 02:33:33

    And I forgot to say what an interesting article. I had no idea the Oric had been cloned. Was it under licence or unauthorised?

    Reply

  8. Hans
    Feb 12, 2016 @ 19:52:48

    Nice read. Thank you. The Prawez machines are stil on my hunt list 🙂 Desprite doing the German wiki page about (https://de.wikipedia.org/wiki/Prawez_(Computer) ) I only own parts of a damaged 8M 😦

    Reply

    • Hrisimir
      Jul 27, 2017 @ 11:12:04

      Dear Hans,
      I still possess a working and well stored Pravetz machine. The model is Pravetz 16. In case you are interested, send me an e-mail and we could deal. 🙂

      Reply

  9. SS
    Jan 02, 2019 @ 12:20:11

    Hello, I found old Pravetz 8D but the chip 6522 is missing 😦 . Can I test without this chip?

    Reply

    • Mickael Pointier
      Nov 16, 2019 @ 12:19:30

      The VIA 6522 is a fundamental piece of the system, but it’s normally easy to find.
      Maybe ask on one of the Oric forums or Facebook pages, on the defence-force forums at least there are some people who own Pravetz computers who could help if you need advice.

      Reply

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