#: 10283 S10/OS9/6809 (CoCo)
    15-Apr-91  17:52:18
Sb: #10239-#hard drive format
Fm: Lee Veal 74726,1752
To: Hugo Bueno 71211,3662 (X)

Here are the parameters that I use for my B&B setup:

 dmode /hx

 drv=01 stp=03 typ=80 dns=02 cyl=0267 sid=04
 vfy=00 sct=0022 tos=0022 ilv=16 sas=10

 ...which is a 20MB Miniscribe


 dmode /hd

 drv=00 stp=03 typ=80 dns=02 cyl=0354 sid=06
 vfy=00 sct=0022 tos=0022 ilv=16 sas=10

..which is a 40MB Miniscribe

Note that the SCT= and TOS= parameters are both set to 0022 instead of 0020
like yours (and mine used to be). I read a spec on drive capacities and it said
thrt the Sectors per track (IBM-sized; 512 bytes) was 17. I said, "Hmmmm, if
you can get 17 of the 512-byte sectors on a track, then you should be able to
get 34 of our (OS-9's) 256-byte sectors.

     Calculations for 20MB Miniscribe Drive

  Cylinders      Heads   Sec/Trk  Sec. Sz
        615   x    4   x   32   x   256   =   20,152,320
        615   x    4   x   34   x   256   =   21,411,840

                                     Extra=    1,259,520

 ----------

    Calculations for 40MB Miniscribe Drive

  Cylinders      Heads   Sec/Trk  Sec. Sz
        852   x    6   x   32   x   256   =   41,877,504
        852   x    6   x   34   x   256   =   44,494,848

                                     Extra=    2,617,344

     The specs for the 40MB Miniscribe drive was somewhat less than 852.
     I noticed the highest cylinder that the specs listed as formattable
     was quite a distance from the "landing zone" (park track). It did not
     take a brilliant deduction but I figured that the space between the
     park track and the highest track was usable. So, I modified my
     descriptor to format it, too. It formatted fine, and I've been using
     that space (and the 2 extra OS-9 sectors per track) nor about a year.
     It turned out that using the documented high track made the calculations
     come out to a size that more closely  matched what a typical 40MB hard
     drive was supposed to be on an IBM or clone system. OS-9 WINS AGAIN!!!!

 Try it out.

 Lee



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