Samsung WA31273A Technical Manual page 48

AT INTERFACE and ATA COMMANDS
6-2-3-11 IOCS16- (Drive 16-bit I/O)
IOCS16- indicates to the host system that the 16-bit data port has been addressed and
that the drive is ready to send or receive a 16-bit word. This is an open collector output.
• When transferring in PIO mode, if IOCS16- is not asserted, DD0-7 are used for 8-bit
transfers.
• When transferring in PIO mode, if IOCS16- is asserted, DD0-15 are used for 16-bit
data transfers.
6-2-3-12 IORDY (I/O Channel Ready)
This signal is active low to extend the host transfer cycle of any host register access
(Read or Write) when the drive is not ready to respond to a data transfer request. When
IORDY is not negated, this signal is in the high impedance state.
6-2-3-13 PDIAG- (Passed Diagnostics)
This signal is asserted by Drive 1 to indicate to Drive 0 that it has completed diagnostics.
A 10K pull-up resistor is used on this signal by each drive.
Following a power on reset, software reset or RESET-, Drive 1 negates PDIAG- within 1
msec (to indicate to Drive 0 that it is busy). Drive 1 then asserts PDIAG- within 30
seconds to indicate that it is no longer busy, and is able to provide status. After the
assertion of PDIAG-, Drive 1 will be unable to accept commands until it has finished its
reset procedure and is Ready (DRDY=1).
Following the receipt of a valid Execute Drive Diagnostics command, Drive 1 negates
PDIAG- within 1 msec to indicate to Drive 0 that it is busy and has not yet passed its
drive diagnostics. If Drive 1 is present then Drive 0 waits for up to 5 seconds from the
receipt of a valid Execute Drive Diagnostics command for Drive 1 to assert PDIAG-.
Drive 1 clears BSY before asserting PDIAG-, as PDIAG- is used to indicate that Drive 1
has passed its diagnostics and is ready to post status.
If DASP- was not asserted by Drive 1 during reset initialization, Drive 0 posts its own
status immediately after it completes diagnostics, and clears the Drive 1 Status Register
to 00h. Drive 0 will be unable to accept commands until it has finished its reset
procedure and is Ready (DRDY=1).
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4 WA31273A / WA32543A / WA33203A / WA3216A / WA31083A / WA32162A