[Simh] altairZ80 floppy disk binary files

[Peter Schorn]

Hi

1. The file format for the AltairZ80 DSK device is basically a sequence
of 77 tracks with 32 sectors of 137 bytes (CP/M 2 can also handle disks
with 254 tracks). This is modeled after the FD-400 hard-sectored floppy
drive.

2. If you want to mount an IMD disk under CP/M 2 use the cpm2.zip from
here http://schorn.ch/cpm/zip/cpm2.zip and use the command

attach hdsk1 <yourfile.imd>

to mount the IMD file "yourfile" as disk J:

Note that the BIOS of the supplied CP/M 2.2 only supports 128 bytes
sectors. I updated cpm2.zip to include cpm2_imd which demonstrates this
- just use altairz80 cpm2_imd and a blank SSSD 8” IMD will be mounted on
drive J:

Peter
-----
peter.schorn at acm.org


On 22.09.14 14:32, Malcolm Macleod wrote:
> A couple of questions about virtual-floppy-drive files under altairZ80.exe:
> 
>  
> 
> 1.           SIMH’s file-format for representing floppy drives
> 
>  
> 
> Can anyone point me to some information about the file-format for Floppy
> Disk Drives in altairz80.exe under SIMH ??  Section A.2 of Appendix 1 of
> “simh_doc.pdf” says that: “Floppy disks are represented as unstructured
> binary files of 8b data items. They are nearly identical to the floppy
> disk images for Doug Jones' PDP-8 simulator but lack the initial 256
> byte header. A utility for converting between the two formats is easily
> written”.  However, I’ve not been able to find a description of how
> these files are structured.  For example, I’ve noticed that when I
> create a blank disk in altairz80.exe (eg by using the command “ATTACH
> DSK1 NEW.DSK”, then formatting it using FORMAT.COM on the supplied CPM2
> disk) that the floppy disk file seems to have an extra 9 bytes between
> the actual sector data, so it doesn’t seem to be just raw sector data.
> 
>  
> 
> 2.           How do I mount ImageDisk (IMD) disk images under altairz80?
> 
>  
> 
> The “AltairZ80 Simulator Usage” PDF (altairz80_doc.pdf) makes reference
> to IMD files being supported, but I’ve not been able to find any
> information about how to do this.  For example – if I want to mount an
> existing CP/M 2.2 SSSD 8” IMD image, with 26 x 128 byte sectors, as B:
> (under altairz80.exe), how do I do this?
> 
>  
> 
> Thanks,
> 
> Malcolm.
> 
> 
> 
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