Note that this will build a disk image that has no operating system on it.
See the Z80 Retro! CP/M repo for information on how to format
an SD card and install a bootable image into drive A which we normally refer to as "slot zero".
The image created by this Makefile is intended to be stored into any slot OTHER than slot zero.
Below is a discussion of how and where things are stored on an SD card suitable for use
in a Z80 Retro! system. By default, the Makefile has been configured to function
out-of-the-box if you are using a Raspberry PI as your development platform as seen
in the
Z80 Retro! Playlist
on the John's Basement YouTube channel.
If you are using a different system, you will want to create a Make.local file to
override the defaults as needed by your platform. You should not have to alter
any of the other Make* files unless you are adding or removing programs from the
filesystem.
If you find this to be untrue then you are either doing it wrong or there is an error in how this project has been prepared. Please post comments to let the maintainers know!
We can use the cpmtools package to do this. On a Debian-derived linux system we can install it like this:
sudo apt install cpmtools
It is not documented, but a diskdefs file in the current directory will be searched my the cpmtools commands for the given -f format:
mkfs.cpm -f generic-8k-8m retro.img
Note that the above will save 0xe5 bytes into the directory are of the disk and accomplish nothing more.
Once a filesystem has been initialized by the mkfs.cpm command, files can be added to it like this:
cpmcp -f generic-8k-8m retro.img myprog.com 0:
We can also look at what files are on the CP/M filesystem with the cpmls command like this:
cpmls -f generic-8k-8m retro.img
We consider the one SD partition as a series of 8 megabyte slots.
The goal is to write one disk image (filesystem) to each slot on the disk partition
using the dd command by specifying where on the SD card to put each one.
We consider the slots to be numbered 0-15.
Each slot is 16384 blocks in size (0x4000). seek=01x16384 - 16384 in decimal is the start of the second disk slot. (You don't need the seek statement for disk 0, but it's included for consistency.)
CP/M can can support up to 16 8MB disks. The Z80 Retro! BIOS can be configured to map zero or more of each such disk to a "slot" on the SD card.
sudo dd if=0.img of=/dev/YourPartitionHere bs=512 seek=00x16384 conv=fsync # slot 0
sudo dd if=1.img of=/dev/YourPartitionHere bs=512 seek=01x16384 conv=fsync # slot 1
sudo dd if=2.img of=/dev/YourPartitionHere bs=512 seek=02x16384 conv=fsync # slot 2
sudo dd if=3.img of=/dev/YourPartitionHere bs=512 seek=03x16384 conv=fsync # slot 3
Note that you must replace the YourPartitionHere with the disk partition representing your SD card.
It is different depending on your system configuration.
On a generic Raspberry PI, it is typically /dev/sda1.
Also note the different seek values and filesystem names on each of the above dd commands.
You don't have to write to each slot in any order. For instance if you wanted a new disk image in slot 3, you could just write the new image to slot 3. It won't effect the other slots. The image in slot 0 must contain the BIOS (retro.bin) or it won't boot.
See the above examples of using cpmtools for clues on how to put files of your choice onto the disk images.
For more apps that can run on your Retro! board, search the Internet for variations of cp/m software downloads and 'cp/m game download' etc.
Some big archives that might keep you busy for a while can be found here:
http://cpmarchives.classiccmp.org/
https://ifarchive.org/indexes/if-archiveXgamesXcpm.html
https://deramp.com/downloads/mfe_archive/040-Software/Digital%20Research/CPM%20Implementations/COMPUPRO/GAMES/
If you want something to cook on your CPU and test every instruction, you can try
zexall.com and zexdoc.com files found in the CPM.zip file located here:
https://mdfs.net/Software/Z80/Exerciser/