[Simh] altairZ80 floppy disk binary files

[Gregg Levine]

Hello!
Malcolm, what is a Ferguson Big Board ROM? I mean obviously its the
board's ROM array, but what is a  Ferguson Big Board to begin with? Is
it a computer that ran the OS back when such things were more
commonplace?
-----
Gregg C Levine gregg.drwho8 at gmail.com
"This signature fought the Time Wars, time and again."


On Mon, Sep 22, 2014 at 7:14 PM, Malcolm Macleod <malcolm at avitech.com.au> wrote:
> 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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