fhTstPat
#include <Slots.h>
typedef struct FHeaderRec { Size Offset Description long fhDirOffset; 4 0 Offset to directory
long fhLength; 4 4 Length of ROM
long fhCRC; 4 8 CRC
char fhROMRev; 1 12 Revision of ROM
char fhFormat; 1 13 Format - 2
long fhTstPat; 4 14 Test pattern
short fhReserved; 2 18 Reserved
char fhByteLanes; 1 20 ByteLanes
typedef FHeaderRec *FHeaderRecPtr;
Notes: The fHeader record exists at the highest address of a card's declaration
ROM, and should therefore be visible at the highest address in the card's slot
space. The Slot Manager uses the fHeader record to verify that a card is installed in the slot, to determine its physical connection to NuBus ( which
byte lanes are used), and to locate the sResource directory.
The fhDIROffset field of the fHeader record is a self-relative signed
24-bit offset to the sResource directory. The high order byte must be 0, or
a card initialization error occurs.
The fhLength field gives the cyclic redundancy check (CRC) value of the
declaration ROM. The CRC value itself is taken as zero in the CRC
calculation.
The fhROMRev field gives the revision level of this declaration ROM.
Values greater than 9 cause a card initialization error.
The fhFormat field identifies the format of the configuration ROM. Only the
value 1 ( appleFormat) is currently recognized as valid.
The fhTstPat field is used to verify that the fhByteLanes field is correct.
The fhReserved field must be zero.
The fhByteLanes field indicates what NuBus byte lanes are used by the card.
Byte lanes are described in the "Access to Address Space" chapter of
Designing Cards and Drivers for Macintosh II and Macintosh SE.