Tandy 6000 HD, Service Manual

Page: 216 / 416

Service Manual
TANDY 6000/6000-HD
TANDY COMPUTER PRODUCTS ------------------------------------------------------------------------
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9. CD — SDH register
This is loaded with the desired sector size, drive
number, and head number parameters using the following
form.
Bits Sector Bits Head
6 5 Size 2 1 0 Selected
0 0 256 0 0 0 HD 0
0 1 512 0 0 1 HD 1
1 0 1024 0 1 0 HD 2
1 1 128 0 1 1 HD 3
1 0 0 HD 4
Bits Drive 1 0 1 HD 5
4 3 Select 1 1 0 HD 6
1 1 1 HD 7
0 0 Drive 0
0 1 Drive 1
Location D7 should be written as a zero always.
10. CF — Command/Status
Write — The desired command is loaded here, see the
WD1010 manual for available commands.
Read — Controller Status Register
DO When set indicates an error has
occurred; error register should then be
checked.
Dl When set indicates a command is still in
progress and no new command should be
issued.
D2 Not used - forced to zero.
D3 This bit is set whenever the sector
buffer should be written to or read from
by the host, depending upon the command.
D4 This bit reflects the state of the seek
complete line from the drive.
D5 This bit reflects the state of the write
fault line from the drive.