|The not-so-prominent storage format of the 1980s.|
The Sharp MZ-800 monitor inside the ROM has usually these few commands on offer:
M-View/Edit memory (Example: MC000)
D-View memory (Example: DC000)
B-Turn beep on/off
L-Load from tape
S-Save to tape
Shift+BREAK usually aborts any operation.
With the Quickdisk drive connected, the computer switches to a different ROM. The monitor then hosts these additional commands:
QX-Transfer file from tape
Each of the command is typed as a two-letter entry, without parameters. The monitor then asks the relevant information, such as filename, start, end and execution addresses.
It seems that DELETE/KILL is out of the question, so, at least without an operating system (Disk BASIC) the only way to make space is to reformat the disk.
The files need to have an execute address, and it is always used when the file loads. The auto-execution may be circumvented by using 00AD as the start address. Another route might be to choose a RAM address to which all the data files point to, and ensuring there's something meaningful at that address.
The Quickdisk loads 16 kilobytes in 4 seconds. On startup, the MZ800 boots to a disk file as long as there is a file on the disk, regardless of the filename. To bypass this I had to hold the disk drive cover open when resetting. The boot is rapid, which might be because the QD ensures the idle drive head position always points at the beginning of the first file. (=the boot file)
|Using the D command for displaying memory contents. QD shows three files on the disk. The machine code at C000 messes with the character display.|
C000:21 ld hl,$D000
C003:34 inc (hl)
C004:2C inc l
C005:C3 jp $C003
(I suppose the code could be even shorter, but clarity might be lost...)