View Full Version : TurboDos - diskette configuration

November 10th, 2010, 02:43 PM
I hope moderators agree that this is the place to post about TurboDos, which is not Digital Research but is a functional superset of CP/M and MP/M.

I'm trying to install TurboDos 1.3 from distribution disk files onto a machine (IMS 5000SX) with different diskette drives to the original. TurboDos was always sold pre-configured by OEMs for specific hardware, and without driver sources.

Diskette parameters are located in individual REL modules for each drive. These modules were "supplied by vendor" but without source code. TurboDos is highly modular but has no monolithic BIOS with source that can be read and adapted. A system is generated by linking selected modules.

This version of TurboDos is configured for 96tpi 5.25" floppies ("quad density"), I have only 48tpi DSDD Tandons.

Track format is 1024-byte records, 5 records per track, no interlace.

Any ideas or experience on how I can deduce the information I need to patch/remake a suitable FDD driver module? Or hidden trove of source files?

I've trawled the usual online resources, to no avail.

Thanks for anything,

November 10th, 2010, 03:38 PM
You can't read 96 tpi floppies with 48 tpi drives.

You can refit your machine with an appropriately-jumpered 1.2MB 5.25" drive and probably be able to read the disks.

If you have a PC with a 1.2MB drive, you can copy the disks to 3.5" 720K media and retrofit your system with 3.5" drives.

If you need to grab just the files, 22Disk has several TurboDOS definitions, including one for an IMS 5000 with 96 tpi drives.

November 11th, 2010, 02:31 AM
Thanks, Chuck.

My problem isn't just getting the TurboDos files onto my machine. I can do that with 22Disk as you say - in fact I have already done it.

My problem is how to modify the TurboDos FDD driver module to drive 48TPI hardware. I know TurboDos could run in that environment, and I am not planning to change the original FDD hardware that I am preserving.

But I don't have the ASM sources to make an appropriate driver, nor enough information on driver structure to patch the 96TPI driver. I'm hoping someone with TurboDos installation experience will know how it can be done.


November 13th, 2010, 08:59 AM
Hi Rick! Are the TurboDOS source code files available anywhere? They are not available in my recollection. Do you know if anyone has contacted the original authors to release the code under a free/open license? If the source code is not available then it is very difficult to make the changes. I suppose it is still possible but certainly not easy.

If you need 96TPI drives it may be easier to convert some TEAC-55GFR floppy drives to work in DSDD 96TPI mode. I've read your thread on comp.os.cpm and it would be neat if TurboDOS could be resurrected but without source code it is nearly impossible.

Thanks and have a nice day!

Andrew Lynch

November 13th, 2010, 09:20 AM
Have you tried searching the images for a CP/M DPB for the 96 tpi drives? For the IMS 5K box, it should start off as 04 0F...

Can you get TurboDOS to load from a 48 tpi drive? As long as you use only half the drive, it should work, at least to load.

November 13th, 2010, 03:19 PM
According to the IMS TurboDos Implementation Guide (courtesy Bitsavers) there are two ways to generate a customised TurboDos system:

1. From within an existing TurboDos system using TurboDos utilities, or
2. From files located on a CP/M system - but ONLY if you are using the same diskette format for both systems. But this level system generation is just a linking of pre-assembled REL files "provided by vendor", including the specific configured diskette and console drivers. You can only re-configure these drivers if you have Assembler source OR you know exactly which bytes to patch.

So I already have, on a CP/M diskette, all the REL files provided for a system very similar to mine, except for the disk configuration. I know which REL files contain the configurations for FDD A and FDD B, but I don't know how to interpret this data so as to reconfigure for my FDC/FDD hardware. I'll try to disassemble and look for recognisable port setup and I/O sequences and values.

Unfortunately, the OSLOAD.COM loader is also specifically configured for the incompatible disk format, so that will have to be generated as well.


February 10th, 2011, 05:17 AM
Hi! According to this posting on comp.os.cpm, the owners of TurboDOS are no longer enforcing their copyright


This is very good news so if anyone reading this has access to TurboDOS information (documentation, source code, configuration scripts, etc) please scan it in and post. I recommend http://cpm.gaby.de the "unofficial CPM homepage" since TurboDOS is closely associated with CP/M and from the same vintage.

Thanks and have a nice day!

Andrew Lynch