User guide

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This screen is accessed by keying the Read table function key in the previous screen, screen #1 (the
program entry screen), or by keying the "Exit screen" function key in screen #3 (the
formatting screen).
The Error-len: user input field may have a value from "1" to "11"; it is used by the controller when a
data error is detected during a read. If the number of data bits in error is greater than the
Error-len field value, then the controller will report the error as a hard error; otherwise, the
controller will attempt to determine the proper value for the data bits in error. It is
recommended that this field be set to a low value (such as "1", "2", or "3"). If hard errors are
subsequently detected, increase the value slightly. If the field is set to a value much greater
than 5, the likelihood greatly increases that the controller will incorrectly determine the proper
value for any data bits detected in error. This procedure allows media failures of the disk drive to
be detected early, while still allowing for the recovery of data from the disk drive.
The user may partition the hard disk drive into up to 15 partitions. The information about
partitions is stored in a partition table, along with the hard disk master boot program, on the boot
track (normally track zero). The partition table contains 15 partition entries, numbered 0 to 14 -
the partition number is only used during booting. Each partition table entry may be either
unused (assigned a category code of zero), or used by a particular operating system: Heath
CP/M (assigned a category code of 2), Magnolia Microsystems CP/M (assigned a category code of 3,
but not supported at this time), or HDOS (assigned a category code of 4, 5, 6, or 7). A partition
table entry may also be used to reserve disk space for future use (assigned a category code of
1).
The size and position of each partition on the hard disk are specified in cylinders. A cylinder
consists of all of the tracks that can be read without moving, or seeking, the read/write heads in
the disk unit. For example, on a hard disk drive with six heads, a cylinder contains six tracks. A
track contains 32 256-byte sectors or 8K of data - thus, on a hard disk drive with six heads, a
cylinder contains 48K of data. The Heads and Cylinders status fields display the number of heads and
cylinders on the hard disk drive being used. These values are fixed for each of the two systems
presently being offered by Quikdata, and for this reason another Winchester cannot be used.
Each partition may have: A 10-character name, assigned by the user; A category code, which
specifies the operating system which will use the partition; A write-protect flag; An origin, or
starting cylinder position for the partition; and a size of the partition in cylinders. The order of
partition table entries is only significant within a category code. When each operating sy stem
reads the partition table, it ignores all entries that do not have the category code that it is
searching for.
The Check drive function key (#4) is provided on all screens except screen #1 (the program entry
screen). It quickly verifies that the disk drive is functioning by reading one sector on each track on
the disk drive. The entire disk drive must be formatted for this function to complete without
error. This should be performed when setting up a new system to check for proper drive and