Hi all, The reason why I'm interested in this topic is that I recently restored a Ferguson Bigboard I with its CP/M 60K. I'd like to try different programs that are contained in third parts diskettes, but they are of course in a different formats. I am using ANADISK to identify the format and sequence of sectors on disks and 22disk133 to try to read them correctly. Despite having read the definitions of the FCB manual on CP / M, I am finding difficulty in : 1) to determine the block size chosen for different disks; 2) Identify the value AL0 Unfortunately it seems that any further calculation is dependent on the size of the block that would seem a prior undetectable, and i'd need to try different values (starting from 1024,2048,4096 and 8192). Is it in this way? Some format i'd like to determinate: A xerox SWP diskette: SSDD 9,1024 sectors sequence 1,2,3,4,5,6,7,8,9 A MK-83 diskette: DSDD 8,1024 sectors sequence 1,4,7,2,5,8,3,6 Thanks for any helpful hint. Enrico - Pisa - Italy