Sardis Technologies ST-2900 FLEX Conversion Package

The ST-2900 FLEX Conversion Package allows the user to create a FLEX system disk, fully configured for the ST-2900, from the "General" version of FLEX, or from versions of FLEX supplied for some other systems. It was released in September 1984.

FLEX Conversion Package features:

One of the very useful features is the ability to set various values for each floppy disk drive and media: step rate, single vs. double sided, 48 vs. 96 tpi, maximum tracks, at which track to enable write precompensation, and number of sectors per side. It even has optional error logging.

Why did I supply a FLEX Conversion Package rather than a licensed copy of FLEX customized for the ST-2900? I don't remember what the licensing terms were from TSC for FLEX, but for a low volume reseller like Sardis Technologies they probably weren't viable. Then when Frank Hogg and Data-Comp started selling versions of FLEX adapted for the Radio Shack Color Computer, but at a fraction of the normal list price of FLEX, I decided to rather provide a way to use these lower cost versions. This saved my customers lots of money, even after also buying the conversion package from me. It also eliminated the need for me to buy multiple copies of FLEX (in order to get a reseller discount), with the risk that some would remain unsold. And I avoided having to ship stacks of heavy manuals all over the world.

Although STAR-DOS/SK*DOS from Star-K Software is supposed to be compatible with FLEX, I experienced problems running it on the ST-2900, especially when using printer spooling, so do not recommend it at this time. I suspect it is due to my drivers and STAR-DOS/SK*DOS both using some of the same memory locations that TSC indicated were not used by FLEX, so could be used by other software. If anyone finds and fixes these issues, please let me know, and I will update this note.

I have found source code files and assembler listings showing I was working on an improved version of the FLEX Conversion Package at the end of 1985. One of the new features was a caching floppy disk driver that could read and write an entire track in one revolution. This would significantly speed up reads and writes regardless of the sector interleaving on the disks. The 8KB track buffer was to be located on the RAM-512 board to avoid reducing main memory available for user programs. This software was also going to allow the user to re-assign any of the four FLEX logical drive numbers to any driver and physical drive from the pool of all available drivers and drives. This would be especially useful when more than four drives (including RAM-Disk and similar virtual drives) are installed. But this software was never finished or documented.

icon to link to FLEX Conversion Package User Manual ST-2900 FLEX Conversion Package User's Manual.
(2.6MB .pdf scanned image)
icon to link to additional notes for FLEX Conversion Package -- not available yet Other notes for the ST-2900 FLEX Conversion Package. Includes addendum/errata to the manual, etc.
(not available yet)
(??KB .txt)
icon to link to DSK image file for FLEX Conversion Package Bootable DSK image (35T/SS/SD FLEX format) of ST-2900 FLEX Conversion Package, as distributed.
(12KB .zip)
icon to link to DSK image files of source code for FLEX Conversion Package Two DSK images (35T/SS/SD FLEX format) of source code for ST-2900 FLEX Conversion Package components.
(39KB .zip)

"FLEX" was a trademark of Technical System Consultants (TSC).
"OS-9" is a registered trademark of Microware LP.

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Last revised 2022-Oct-13 13:15 PDT.
Copyright 2018-2022 David C. Wiens.

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