[Simh] altairZ80 floppy disk binary files

[Malcolm Macleod]

Hi Peter,

Thanks for the fast response.

That worked, when used with the SIMH command "SET HDSK1 FORMAT=SSSD8S".

Note that I needed to use altairZ80.exe downloaded from your site for this to work (ie "V3.9-0 build 1625").  The Windows executable of V3.9-0 downloaded from the main SIMH site generated errors mounting the IMD file.

FYI - I'm using altairZ80 to rebuild a Ferguson Big Board ROM from source.  AltairZ80 is a great platform for this work.  Thanks for making it available.

Malcolm.

-----Original Message-----
From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Peter Schorn
Sent: Tuesday, 23 September 2014 3:03 AM
To: simh at trailing-edge.com
Subject: Re: [Simh] altairZ80 floppy disk binary files

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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