OF-Link allows one (or more) instances of the TSC 6809 FLEX operating system to run under OS-9/6809 Level II (or NitrOS-9/6809 Level 2) on the Radio Shack Color Computer 3 (CoCo 3).
OF-Link is an OS-9 module that acts as an interface between the FLEX and OS-9 operating systems. An actual copy of the FLEX operating system runs concurrently with the (Nitr)OS-9 operating system, but OF-Link translates all FLEX disk and console and printer I/O calls to OS-9 system calls. (This is different from the Wine compatibility layer that lets Microsoft Windows applications run on Linux, but doesn't use the actual Windows operating system code.) OF-Link allows you to run many of your existing FLEX programs under (Nitr)OS-9 without requiring you to obtain OS-9 versions of them. This is especially useful where a program was only available in a FLEX version.
OF-Link was first advertised in RAINBOW magazine in the September 1988 issue. It was enthusiastically reviewed on pages 16-17 in the April 1989 issue of '68' Micro Journal. The review had a few minor errors, and subsequent updates eliminated some reported problems:
Only version 0.5 was developed and distributed. Sales of OF-Link were so few that I couldn't afford to spend the required time to finish implementing the planned enhancements to create version 1.0. OF-Link was an interesting and useful product, but a marketing and financial flop.
GIMIX O-FLEX from GMX was a similar software package that ran under OS-9 GMX II and GMX III versions of OS-9 Level II on SS-50 bus computers.
Programs that run under FLEX can be downloaded from various sites such as here and here. Archived issues of '68' Micro Journal have much useful information on FLEX and programs for FLEX, several FLEX manuals can be downloaded, and you can read about the history of FLEX. You can even find source code (well commented disassembly) for FLEX v3.01 (files FLEX.TXT and FLEXFMS.TXT in flex_srces.dsk).
Peter Stark developed an operating system called SK*DOS (originally called STAR-DOS) that was mostly compatible with FLEX, and also works with OF-Link:     
Since the TSC FLEX operating system may now be freely distributed, as may the NitrOS-9 operating system, and now also the SDisk3 floppy disk driver, I am able to supply an Ease of Use (EOU) disk image (see below). This is much easier to use than the software on my original distribution disk which required many installation steps. The EOU disk is bootable and ready to run, and includes the SDisk3 driver pre-installed in the NitrOS-9 OS9Boot file, a shell procedure file that calls a pre-configured version of OF-Link, and a FLEX virtual disk containing the linked FLEX v3.01 operating system and related utilities. This EOU image runs just fine on the VCC 2.0.1b and 126.96.36.199 CoCo 3 emulator. One user has reported successfully running it on a real CoCo 3, although he used a CoCo SDC instead of real floppies.
The format of the FLEX virtual disk images (contained in OS-9 files) used by
OF-Link is unique to OF-Link and is not supported by any other software except
for my UFDR program, which runs under Windows.
FLEX DSK image files can be opened by the VCC CoCo 3 emulator (also running
under Windows) as emulated physical disks. Linux users can't run either of
these programs (except maybe under Wine?). OF-Link running on real CoCo 3
hardware can use the CoCo SDC floppy disk emulator to open FLEX DSK image files,
but CoCo SDC doesn't support many of the common FLEX disk configurations. This
makes it difficult for non-Windows users to get files from FLEX DSK images for
use with OF-Link. Ideally I would enhance OF-Link with the ability to directly
open an OS-9 file containing a FLEX DSK image in any configuration and/or write
a program (for Windows, Linux, and macOS) that could convert a DSK image into
the OF-Link format.
((( dsktool ))) ===
The source code for OF-Link won't be available for a while. I haven't yet found a copy that matches the distributed binaries, and the most recent copy of my source code contains lots of modifications that are incomplete and probably not runnable. (I had started working on version 1.0 but never finished it.)
When you read the two manuals shown below, display them at a large size. The Letter Gothic font I used makes it very hard to distinguish between a period and a comma when displayed at a reduced size. If anyone knows of a better version of this font, please let me know. (I found the similar Financial font which is better, but not perfect, either.) The Letter Gothic font that was printed on daisywheel printers in the 1980's was much better.
OF-Link User's Manual.
OF-Link Additional Notes.
DSK image (35T/SS/DD CoCo OS-9 format) of original OF-Link
DSK image (40T/SS/DD CoCo OS-9 format) of EOU version of
OF-Link that is ready to boot NitrOS-9 and FLEX, with instructions.
DSK image (40T/SS/DD CoCo OS-9 format) of source code for
OF-Link and related programs.
(not available yet)
"FLEX" was a trademark of Technical System Consultants (TSC).
"OS-9" is a registered trademark of Microware LP.
"Radio Shack" and "Color Computer" are trademarks of Tandy Corp.
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Last revised 2022-Jun-23 10:33 PDT.
Copyright 2018-2022 David C. Wiens.