PRG/LNX/SDA/SFX
	original load address in first two bytes (ignored)
	loaded to MEMBOT+1
	BASIC lines
	two zero bytes (end of basic program)
	binary data (if any)
	where the basic program is:
		16 bit	pointer to next line (wrt original load address)
		16 bit	line number
		BASIC expressions (tokenized)
		one zero byte (end of line)
	typical values of MEMBOT:
		801h (C64).
P00
	26 byte header:
		ix	sz	desc
		00h	07h+1	C64File\0
		08h	10h+1	original 16 character c64 filename, padded with 00h (!!!!)
		19h	01h	record size for rel files (00h otherwise)
		1ah	...	original file image with load address (same as PRG)
		data blocks are 254 bytes each, excluding the NEXT pointer.
D64
	174848 for 683 blocks of 256 bytes each.