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Professional-DOS @ D81.DE

A Floppy-Speeder from Mikrotronic for the C64 home computer, it's derivatives and peripherals.

The Professional-DOS Floppy-Speeder from Mikrotronic for the Commodore home computers C64, C128 and C128D and it's peripherals C1541, C1541-C and C1571 was one of the Super-Floppy-Speeders. This class of speeder systems were mostly equipped with hardware modification boards and a parallel cable of course. Well known products are Dolphin-DOS from Dolphin-Software, Prologic-DOS (Classic) from Jann Datentechnik, Turbo-Trans from Roßmöller and Professional-DOS from Mikrotronic.
Professional-DOS is also known as DiskDemon sold by Datel in the UK or RapidDOS Pro from Chip Level Designs located in North Amerika (as discussed in 1994, see the thread: »Can you identify this fastload HW?« ).

If you are mainly interested in the history of Professional-DOS, it's inventor Klaus H. Roreger and his company Mikrotronic, then you may want to visit Tim Schürmann's pages (unfortunately german only), who is also very interested in this speeder system.

The Story

In the second half of the 1980-ties, when I used my C64 for every day work, I always wished to have a Professional-DOS speeder system. It was tested as the fastest speeder system in most of the hardware comparisons of the C64 magazine 64'er. Well, it's not the fastest system overall, but if you only take loading programs into account and if you only look at direct disk transfers (without caching the whole disk into RAM), Professional-DOS is the brute-force attack against floppy mechanics.
But I was not able to buy such a system, I never got enough money for it. And mostly other important hardware had a higher priority (1764 RAM expansion and a more reliable 1541-II drive) to get. In the 1990-ties I tried to get a second-hand system, but never had enough luck to get one.

The time was working with me. In 2002 a good friend and long-time comp.sys.cbm-fellow bought a huge collection of different hardware speeder systems at ebay. It contained a floppy drive expansion board of Professional-DOS and a C64 expansion port board of the speeder system Floppy-Flash. He decided to sell these pieces to me, because he was mainly interested in a manual for Prospeed 1571 and a hardware of Prologic-DOS classic and already knew, that I was desperately searching for a (cheap) Professional-DOS hardware.

A short time later another german Professional-DOS user asked in the GO64-Forum for some help to repair his dead floppy speeder hardware. To potentially help him and to fulfill our curiosity, we started a little project to analyze the exact working of the hard- and software of Professional-DOS. When I got my version of the hardware, it didn't work also although my friend stated it to be working in his drive. Therefore a technical analysis became even more important to find the fault.

The workout

The whole hardware was documented as good as possible, all parts were disassembled and analyzed systematically. You can view the results of these steps at the Hardware-Area of this site. You will find a picture gallery of high quality scans of the board and some deeper looks into the ROM contents and electronics.

The user, who searched for some help for his faulty hardware provided also some scans. Because he owns a complete version of Professional-DOS (named »Professional-DOS Release«) not only the PCB could be documented, but also the german manual as well as the contents of a utility disk supplied with Professional-DOS Release. Later he made some electronic measurements, too. This makes it possible to do a fine comparison between these two hardware revisions.

You will find the contents of the documentation of »Professional-DOS Release« at the Release section of the Versions-Area. The manual will get it's own area, because it is going to be converted into eText as a contribution to the iDoc=-Project. Perhaps it will be translated into english, but only if no one can provide some scans of an english version of Professional-DOS.

Help wanted

You could help all the Professional-DOS owners, especially me and other interested people to learn more about this great speeder hardware. You could provide some more informations about the different versions and the possibilities to extend existing parallel speeders (Speed-DOS, Floppy-Flash, Turbo-Access, ...) by the Professional-DOS floppy expansion.

The following items of your desired hardware would be very welcome:

  • Scans (1200 dpi) or high resolution photographs of your hardware board, the bottom side as well as the top side with and without any removable part.
  • Any IC labeling of the smaller TTL ICs you are able to read or reconstruct. Preferrably identified by high resolution scans and some image manipulation, but you may also use the »spit onto«-method. Maybe you own a different hardware revision with other parts.
  • A crossconnection table of your hardware as shown in the Electronics section. Please use the provided IC naming scheme, if your hardware is not completely different.
  • Scans or already to eText converted docs of all the manuals, that came with your floppy speeder. Manufacturer and distributor addresses are welcome also if not already mentioned here.


Wolfgang Moser, 2003-05-25,  ,  ("contact me" form disabled due to too high demand, sorry)