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View Full Version : Where to locate a custom cold bootstrap in CF compatible with CP/M and DOS?



Plasmo
February 11th, 2018, 05:29 AM
I'm working on a homebrew Z280 computer that has no ROM but boot out of compact flash instead. The cold bootstrap code is small, about 128 bytes, that copies a CF loader into memory and execute which, in turn, load & execute bigger program. My question is where to put the cold bootstrap code. The easiest location is in CF's first sector (boot sector). But there are so many different CF formats out there, I don't know what kind conflicts will result from a custom 128-byte data located in the boot sector. I did looked up Master Boot Record format and convinced myself that the Z280 cold bootstrap code is small enough to fit within the MBR structure. What about CP/M disk format? I think normally the CP/M loader is in the first 2 sectors, but is it reasonable to relocate CP/M loader to the 2nd and subsequent sectors of a CF? I'm new at this, but I wonder whether it is possible to format a CF so it can move between the PC environment (FAT) and CP/M environment?