Hi at all. I have few questions on how the geometry is calculated.
1) I would like to understand. this table represents an 3740 IBM standard disk D: Drive Characteristics 1944: 128 Byte Record Capacity 243: Kilobyte Drive Capacity 64: 32 Byte Directory Entries 64: Checked Directory Entries 128: Records / Extent 8: Records / Block 26: Sectors / Track 2: Reserved Tracks Its DPT is: 1A00 03 07 00 F200 3F00 C000 1000 0200 Or: SPT = 001A = The number of 128 byte records per track. BSH = 03 = The block shift count. BLM = 07 = The block mask. EXM = 00 = The extent mask. DSM = 00F2 = Disk storage maximum (the largest block number). DRM = 003F = Directory maximum (the largest directory entry). DAB = 00C0 = Directory Allocation Block AL1: = 00 & AL0: = C0 [0C0H] CKS = 0010 = Directory check size. OFF = 0002 = Track offset (number of reserved tracks). I already know there are 26x128x77 = 256256 bytes But how does this table represent them? 1944 sectors x 128 bytes = 248832 bytes = 243x1024 is the capacity actually available for the files The system takes 26 sects/track x128 bytes/sect x2 sects= 6656 bytes So 256256 - 248832 = 768 bytes They are for the directory but how does this number come out? 2) I have instead this table of a BASF 6104 Floppy Disk Drive managed through a Shugart SA-1403 SASI Controller: B: Drive Characteristics 9216: 128 Byte Record Capacity 1152: Kilobyte Drive Capacity 64: 32 Byte Directory Entries 64: Checked Directory Entries 2048: Records / Extent 128: Records / Block 512: Sectors / Track 1: Reserved Tracks Its DPT is: 0002 07 7F 0F 4700 3F00 8000 1000 0100 SPT = 0200 = The number of 128 byte records per track. BSH = 07 = The block shift count. BLM = 7F = The block mask. EXM = 0F = The extent mask. DSM = 0047 = Disk storage maximum (the largest block number). DRM = 003F = Directory maximum (the largest directory entry). DAB = 0080 = Directory Allocation Block AL1: = 00 & AL0: = C0 [0C0H] CKS = 0010 = Directory check size. OFF = 0001 = Track offset (number of reserved tracks). Oddly, the controller seems to manage the drive as 32 sect/tracks x256 bytes/setc x77 trakcs x2 heads In this case I don't know exactly the parameters of the diskette 9216 sectors x 128 bytes = 1.179.648 bytes = 1.152x1024 is the capacity actually available for the files The system takes 512 setcs/track x32 bytes/sect x1 tracks = 16.384 bytes In case 1 the gross capacity is 256256 while in case 2 which is it? 3) what could be the correct parameters to insert in 22disk in order to transfer files between a type 2 disk and msdos? Thanks a lot at all who will wish to answer to me. Enrico
