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Dear 8080A CPU Builders,
I call them Virtual Disks, but they are the binary files in FAT16 that create a virtual disk in CP/M. What would you call them? Harold has asked how to change disks in CP/M. The firmware, on boot up, defaults to opening the following files for the first 4 virtual disks. DISK-A.BIN, DISK-B.BIN, DISK-C.BIN and DISK-D.BIN. You can at the boot up time redefine the files to be opened. Your options at the first boot screen is "M" for Monitor Mode, "C" to boot CP/M from the first virtual disk or pressing the numbers 1 through 4 will allow you to enter a different file to be opened for that drive (1=A, 2=B, etc). The process of opening the (fat16) file for use as a virtual disk involves finding the file in the directory, then setting various pointers to indicate the starting cluster, starting sector, the current relative cluster, sector within that cluster, etc. This is all handled in a routine that remains resident in BIOS. I intend at some point to write a CP/M utility to change the disks while CP/M is running. Another project on the back burner! :) I was thinking of adding more FAT16 file functions. Namely I was thinking to have a config file that would store your selections of files for Disks A to D. Also, I would like to add the option to load and execute a hex file directly from the SD Card. Open to more suggestions.... Regards, Josh Bensadon |