Hmm .. Missing Cromemco 168 images

[cro memcos]

So,   correct me if I'm wrong,  but is seems that on the Github I don't have a working set of Cromix 168 floppy images. I am shocked!!

I thought I'd just take a moment to review how the Github Directory structure was designed to work ...

Code images are in cromemco/code/disks

catalog.txt is the master text file indexing all floppies and hard disks I have

Subdirectories inside disks

IMD    Diskettes laboriously imaged to Dunfield Image Disk Format

DSK   Conversions of IMD to raw DSK sector format

HxC   Conversations of IMD to HxC floppy emulator format

RCOPY  Rcopy images of diskette using rcopy command

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I use and highly recommend the HxC emulator

However I just noticed whilst trying to mount HxC images for Cromemco 168, diskettes 694,695,696  I get errors like this

Luckily I have the 3.5" copies of the original 8" masters but I can't make .IMD files anymore,  but there is a potential to make .rco  rcopy files on an actual Cromemco System but then how to get them off the system to a PC   (my PCCOM does not work on current system and that was my only way back in 2009 when I did the work)

Also I notice that diskettes 525,526,527 are also missing.  Not good.

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So if anybody has .IMD imagedisk files of the 3 , 8" cromix 168 distribution diskettes I am all ears.

The HxC emulator has a Windows/Mac program that can convert from .IMD to may output formats like DSK and HxC (.hfe)

regards marcus

[Peter Higgins]

Re Cromemco 168, diskettes 694,695,696

There is a note in the catalog indicating these images are specified incorrectly as 300 RPM whereas they should be 360 RPM. This problem affects many of the system disk images in the repository, and the images need to be fixed else they will not be readable from the Gotek emulator.

Forum member Graham identified this issue in a discussion started back in December titled "Cromix Plus Installation Disk Set". These were his comments:

Some of the images with the speed issue have a comment in the catalog but not all.  Because the speed is 300rpm rather than 360rpm.  When the IMD or an HFE derived from a the IMD is viewed in the HxC software the sectors are scrunched up into about 3/4 of the disk.  This seems to then be translated into the HFE/SCP that i use for goteks/greaseweazle.

There are probably better ways to fix this but i found that if i exported the images as raw (IMG) and then re-imported them from raw then i could change the RPM to 360.  In the HxC tools you use the "Load Raw Image" button rather than the "Load" button.  This opens a dialog where you have to describe the disk format and only one format is allowed so this won't work for the boot disks which have a special boot track with a different format to the rest of the tracks.  For a large Cromix Disk i used 77 tracks, 2 sides, 16 sectors per track, 512 bytes per sector, 500k bit rate, and 360rpm. For a large Uniform Disk i used 77 tracks, 2 sides, 15 sectors per track, 512 bytes per sector, 500k bit rate, and 360rpm. Then export as whatever format you're after.  I like HFE for the goteks because it usually doesn't require a configuration file.  SCP for greaseweazle.

[Damian Wildie]

There was also an earlier discussion of the issue in 2021.

Note : The IMD specification does not include the rotational speed of the diskette.  

When importing from an IMD image, the HxC software must be deriving a best-guess rotational speed from other values.

6. IMAGE FILE FORMAT

       The overall layout of an ImageDisk .IMD image file is:

         IMD v.vv: dd/mm/yyyy hh:mm:ss          (ASCII Header)

         Comment (ASCII only - unlimited size)  (NOTE:  You can TYPE a .IMD)

         1A byte - ASCII EOF character          (file to see header/comment)

         - For each track on the disk:

            1 byte  Mode value                  (0-5)

            1 byte  Cylinder                    (0-n)

            1 byte  Head                        (0-1)   (see Note)

            1 byte  number of sectors in track  (1-n)

            1 byte  sector size                 (0-6)

            sector numbering map                * number of sectors

            sector cylinder map (optional)      * number of sectors

            sector head map     (optional)      * number of sectors

            sector data records                 * number of sectors

         <End of file>

       6.1 Mode value

          This value indicates the data transfer rate and density  in  which

          the original track was recorded:

             00 = 500 kbps FM   \   Note:   kbps indicates transfer rate,

             01 = 300 kbps FM    >          not the data rate, which is

             02 = 250 kbps FM   /           1/2 for FM encoding.

             03 = 500 kbps MFM

             04 = 300 kbps MFM

             05 = 250 kbps MFM

       6.2 Sector size

          The Sector Size value indicates the actual size of the sector data

          occuring on the track:

            00 =  128 bytes/sector

            01 =  256 bytes/sector

            02 =  512 bytes/sector

            03 = 1024 bytes/sector

            04 = 2048 bytes/sector

            05 = 4096 bytes/sector

            06 = 8192 bytes/sector

---- On Fri, 17 May 2024 07:43:20 +1000 Peter Higgins <higgin...@gmail.com> wrote ---

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[Damian Wildie]

Lines 306-360 of https://github.com/jfdelnero/HxCFloppyEmulator/blob/main/libhxcfe/sources/loaders/imd_loader/imd_loader.c shows how the HxC software derives the rotational speed for an IMD image.

---- On Fri, 17 May 2024 08:18:02 +1000 Damian Wildie <dam...@wildie.com> wrote ---

To view this discussion on the web visit https://groups.google.com/d/msgid/cromemco/18f837bd651.cc290e85308107.7480254891552823860%40wildie.com.

[Richard Muse]

I found that cromix.168ALL.ta in the repo contains a full, ftar'd set of 168 files. 

I have a set, 4 disks, made from this ftar. The 1st disk is bootable 31.68. The next 3 are the 31.68 full installation disks. A full installation from these disk using the Cromemco provided update1 followed by update2 works properly. Update 1 is intended to 'Build a new root device' on a formatted drive. update2 updates an existing 30.xx installation on a hard drive from the install floppies. Disks 2,3 and 4 could be Uniform format since you supply the floppy device name when running it.

The Cromemco Cromix-Plus System Administrators Guide 023-5020 198807 REVI in the repo is a good reference for the installation.

The 19880817 SUDS Cromix-Plus-XC-6 167 68000 023-9700 also in the repo is a good outline of the final features in 31.67 and also applies to 31.68

I also have 'raw' images of the disks made using rcopy.

The disks are formatted using fda not ufda so all contain the single density first track. The original 31.68 Cromemco supplied disks were formatted this way.

If someone needs ufd formatted disks, I'll make a set of those also. Except, of course, the boot disk still has to be non-uniform format.

Richard M

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