Method for Compact Disk-Read Only Memory Drive to Detect Resume Without System Intervention
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2005-Apr-04
Disclosed is a method for a CD-ROM drive to detect system Resume without system notification.
Method for Compact Disk-Read Only Memory Drive to Detect
a method for a CD-ROM drive to detect system
Resume without system notification.
Conventionally, a dedicated control signal or a vendor unique
host command had been used to notify the CD-ROM drive to resume from
Suspend Mode. The control signal method requires unique signal pin
on the interface, but it gives prompt notification to the drive. On
the other hand, the host command method requires no unique hardware,
but will take some time for the drive unit to become ready to accept
host commands. It delays the beginning of Resume process.
described here enables the CD-ROM drive to begin
Resume process promptly after POR (Power On Reset) and yet requires
no additional hardware.
CD-ROM drive receives Suspend command, the drive not
only saves it's current drive parameters, but also sets the Suspend
flag to TRUE to save the information that the last drive power off
was a System suspend and not a System power-off.
At the next
power-on, the drive first refers to this Suspend
flag. If it is set to TRUE, the drive immediately proceeds with
Fig. 1 schematically shows the suspend entering
process. When CD-ROM Drive receives SUSPEND (C3) command, the drive
begins storing drive parameters into flash memory. When the drive
completes the storing process, it sets the Suspend Flag and enters
READY TO SUSPEND mode. In READY TO SUSPEND mode, power can be shut
down at any time. The status register shall be set to Busy during
SUSPEND IN PROCESS.
If the Host
System fails to suspend for some reason, and
accordingly decides to cancel suspend operation, the Host will then
issue a RESUME/CLEAR-FLAG (C4) command.
drive is powered off during SUSPEND IN PROCESS mode,
the drive is powered off without setting the Suspend Flag. In this
case the drive shall perform regular power-on process at the next
drive receives a C4 command during READY TO SUSPEND
mode, the drive will reset the Flag, and r...