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Bootblock for CP/M

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Neelix

New Member
Joined
Jun 27, 2019
Messages
8
Hello,

I please to help. I tried to make a CPM floppy image booting. I often download floppy disk content for CPM softwares as zip files But I now want to create a bootable CPM disk image I'm familiar with cpmtools. It's possible to create bootable boot images with it. But, therefore, I need a bootblock file Could someone tell me where to find any ?

Or, maybe other possibilities to create boot floppy images from a CPM system floppy zip file.
 
In cpmtools, you define the geometry of the disk. The "boottrk" entry defines the number of tracks not used by CP/M. How these are used is not specified.

There is no standard boot block for CP/M, because booting depends on the hardware. On a PC, the BIOS (running from ROM) will read the boot sector, but CP/M systems do not necessarily have such a ROM. So you need to specify the actual hardware you want to use, i.e. its floppy controller and how it runs code after turning on power.
 
Neelix,
Since you already have cpmtools, do you know if it was built with libdsk included? If so, DSKTRANS can write
your floppy in various formats.

Here is a good guide: http://forums.debian.net/viewtopic.php?f=16&t=112244
Search for "LIBDSK - SUPPORTS" and start reading there about DSKTRANS, as the beginning
posting just describes how to prepare and install cpmtools with libdsk.

If your .ZIP files contain *.TD0, *.IMD, *.RAW, files the above guide explains how to get those file types to floppy
as a bootable image. it shouldn't take long to do that, assuming you have the proper cpmtools & libdsk definitions.

If you give us a clue as to what manufacture and model of CP/M machine it is, there may already be definitions pre-defined
that you can use.

Larry
 
Since you already have cpmtools, do you know if it was built with libdsk included?
Click to expand...
It is. I compiled cpmtools with libsdk.

Here is a good guide: http://forums.debian.net/viewtopic.php?f=16&t=112244
Click to expand...
I followed this tutorial, but I'm unable to convert IMD images to other formats, there become unreadable.

If you give us a clue as to what manufacture and model of CP/M machine it is, there may already be definitions pre-defined
that you can use.
Click to expand...
I would run Cromemco CPM on a Cromemco emulator.
 
Neelix said:
I would run Cromemco CPM on a Cromemco emulator.
Click to expand...

IIRC, Cromemco never had an official CP/M, they had CDOS which was their workalike. I don't remember how compatible they were.

In addition to knowing it's a Cromemco, we'll also need to know the floppy controller type. There were three, the 4FDC, 16FDC, and 64FDC.
 
Are you trying to find an existing bootable CP/M or build and boot your own ?

The 16FDC at least simply loads 128 bytes of memory at 0x0080 from the FDC and jumps to it. The rest is up to you. The disk format is a bit weird because with double density disks not all tracks are double density.

You might find http://www.hartetechnologies.com/manuals/Cromemco/ useful as it includes the 16FDC boot and BIOS code.

Z80Pack has a Z1 emulator and the relevant CP/M 2.2 disks as well as CDOS and Cromix. The emulator is pretty good in some areas (very good on disk, nice pretty front panel, does dazzler) but weak on others. The serial emulation in particular is very very incomplete and inaccurate - but good enough for emulating the existing products.

Alan
 
It's a 16FDC boot disk image (.IMD image), but I don't know the type of floppy used by the emulator.
 
If you have DOSBOX installed in Windows or Linux, use it to se if the .IMD file has more information in the .IMD file.
Copy the *.IMD files to your /home/user/path/to/dosbox/
then copy the IMDA.*, IMDU.* utilities form Imagedisk there also.
execute DOSBOX. then from within DOSBOX use the following command

C:\>IMDA YOUR.IMD > YOUR.TXT

View YOUR.TXT to see if any drive size is mentioned.


If you use IMDU to create a .RAW file that piped information to the YOUR.TXT file can also give
some good clues. An example is:

Assuming 1:1 for Binary output
0/0 250 kbps DD 10x512
1 2 3 4 5 6 7 8 9 10
D D D D D D D D D D
0/1 D D D D D D D D D D
1/0 D D D D D D D D D D1A
1/1 D D1A D D1A D D1A D D D D
2/0 D D D D D1A D D1A D D D


Larry
 
If it's the same as the one shipped with Z80Pack then the cpmm2.2 disk for the 16FC is an utterly generic 128 bytes/sector 26 sectors/track 8" disk single sided single density disk.
 
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