Date   : Thu, 24 Jan 1991 04:36:18 GMT
From   : cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!src.honeywell.com!skyler.mavd.honeywell.com!rlb@rutgers.edu (Randal L. Barnes)
Subject: 8 meg limit

In article <D4J8V2w163w@cynic.wimsey.bc.ca>,
pevans@cynic.wimsey.bc.ca (Phillip Evans) writes:

> Where did/does the 8 meg limit on logical disk size in CP/M come from?

It has to do with the fact that CP/M uses a 16 bit logical block pointer,
Since CP/M also uses 128 byte logical sectors (sector blocking/deblocking
routines change the physical sector size on the disk but the logical sector
size remains at 128), the maximum logical disk size is:

        65536 * 128 = 8192K

My Molecular Series 9 system has drive B set up as an 8 meg drive.
Doing a STAT B:DSK: yields the following:

            B: Drive Characteristics
        65536: 128 Byte Record Capacity
         8192: Kilobyte Drive  Capacity
         1024: 32  Byte Directory Entries
            0: Checked  Directory Entries
          256: Records/ Extent
           32: Records/ Block
          256: Sectors/ Track
            0: Reserved Tracks

-- 
Randal L. Barnes                    rlb@skyler.mavd.honeywell.com
Tea, Earl Grey, HOT!                Honeywell Military Avionics Division
                                    612/542-5021