Most of this issue is taken up with a general look at the CP/M and PCP/M Systems on Sharp computers. Here, I concentrate on the Disk Parameter Block in Microtechnology CP/M 2.2.2.15 on the MZ-80A, as displayed by DPB.COM:-

Parameters for Drive A:

80 Sectors per Track seems impossibly high until you realize that, in M-T's CP/M 2.2 on the MZ-80A, a 'Logical Track' extends over BOTH sides of a disk and there are therefore only 35 'Logical Tracks' on the disk as a whole.

Each such 'Logical Track' has a capacity of 128 * 80 Bytes = 10,240 ( 10K ), and the capacity of a whole disk is
128 * 80 * 35 = 358,400 ( 350K ).

BSH = 4 and BLM = 15 both give a block size of 2K ( 2048 bytes ).

EXM = 1 implies that, in this case, a 'Physical Extent' contains TWO 'Logical Extents' and is therefore 32K.

DSM = 169 implies that a disk contains 170 CP/M blocks ( i.e. 340K ).

DRM = 127 implies that the Directory can hold 128 entries.

AL0 - AL1 = 1100 0000 implies that the Directory is allocated the first 2 CP/M blocks ( i.e. Blocks 00 & 01, 4K ).

OFS = 1 implies that Track 0 is reserved for system use, and that the first CP/M block ( Block 00 ) is at the start of Track 1.

The 'User Area' is 340K, but 4K of this is allocated to the Directory, so the actual space available for user files is 336K per disk.

The FILES.COM program in M-T's 5.25" MZ-80A CP/M confirms this figure.

DISCMOD3 reveals the following sections of code on Track 0:-