AppleCD SC: Device Driver Status Calls



My questions concern the AppleCD SC's SCSI driver. In my application
(written in C), I do a Status Call #98 (called GET SIZE). I receive back 11
words (22 bytes):

08 00 00 4A DA
23 00 3C 85 C8
00 4A F9 B8 20
00 00 4B 01 1A
20 24

1) Is this the standard size to be returned by this call?

2) Is there a minimum and maximum size?

3) What is the format of this response?


The information you're looking for is in the AppleCD SC Developer's Guide,
available from APDA. It describes all of the device driver Status calls for
the AppleCD SC, including the inputs and the outputs for each Status call.

In response to your specific questions about Status call 98 (GetSize):

1) The default block size is 2048 bytes.

2) The legal block sizes (in bytes) for the AppleCD SC driver are:
512, 256, 1024, 2048, 2336, and 2340

3) The GetSize Status call will return in scParam + 0 the currently assigned
logical block size of the AppleCD SC. In other words, in the first two
bytes (one word) it returns the logical block size, which by default is
2048.

In your example, the first two bytes are 08 00. 0800 in hex translates
to decimal 2048 -- the default size set for the AppleCD SC. The
remaining 20 bytes are not used for this call.



Published Date: Feb 18, 2012