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Conference 7.286::atarist

Title:Atari ST, TT, & Falcon
Notice:Please read note 1.0 and its replies before posting!
Moderator:FUNYET::ANDERSON
Created:Mon Apr 04 1988
Last Modified:Tue May 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1433
Total number of notes:10312

199.0. "DISC CONTROLLER" by RDGE00::WRIGHT (I AM a member of this company) Tue Aug 16 1988 15:08

Does anyone know what disc controller the ST uses for its 3.5" drive? and if
so have you got any information about it (like an instruction set)

Tony
    
T.RTitleUserPersonal
Name
DateLines
199.1SKITZD::MESSENGERIntrusion Countermeasures ElectronicsThu Aug 18 1988 16:323
    The floppy controller is a Western Digital WD1772, which is compatible
    with 1790/2790 series.
    				- HBM
199.2Not quite ...PERIOD::CONROYSat Aug 20 1988 19:0928
    That's not quite true.
    The 1770/1772 have some built in motor control logic.
    Type I commands on 179X use bit 3 to control head loading (1=load).
    Type I commands on 177X use bit 3 to control the whole motor startup
    sequence (0=enable spin up).
    The type II settle delay (bit 2) is 30 ms, not 15 ms.
    Write commands use bit 1 to disable precompensation.
    Step rates are 2, 3, 5, 6 ms (r[1..0] = 00, 01, 10, 11).
    
    The status register is also slightly different.
    Bit		177X		179X
    7		Motor on	Not ready
    6		Write Protect	Write Protect
    5		Type/SpinUpOk	Type/WriteFault
    4		RNF		RNF
    3		CRC		CRC
    2		TR0/LostData	TR0/LostData
    1		DRQ/Index	DRQ/Index
    0		Busy		Busy
    
    There is a myth floating around that the part is a special
    one. This isn't true. The part is ordinary, and it is in the newest
    Western Digital daa books.
    I, by the way, don't have a data book. I have a copy of some of
    the pages from a data book I found in an office at SRC in
    Palo Alto.
    Just call Western Digital and ask.