31
I
NULL STATE FRAME
23 15 7
s0o I ,UNOE~I.EO~ I (BESERVEOt
0
I
31
iii I
$08 Z/~
$24
IDLE STATE FRAME
23 15 7
VERSION NUMBER I $38 (RESERVEr=)
COMMAND/CONDITION REGISTER (RESERVE0)
INTERNAL
REGISTERS
(32 BYTES)
$28
$2C
$30
$34
$38
EXCEPTIONAL 0PERAND
(12 BYTES)
0PERAND REGISTER
BIU
FLAGS
$00
$04
$O8
$0C
$CC'
SO0
$D4
BUSY STATE FRAME
31 23 15
VERBION NUMBER I $D4
I
7 0
(RESERVE0)
INTERNAL
REGISTERS
(2t2 8YT'ES)
Figure 6-5. MC68882 State Frame Formats
calculations. During an FRESTORE instruction, the format word is written to the FPCP to
initiate the restore operation. When this occurs, the FPCP checks the version number and
frame size values for validity and signals a format exception if they are not valid for this
particular device. The version number is an 8-bit value that identifies the microcode version
of the FPCP, and the format of this number is defined internally by the FPCP. Future devices
will use a unique combination of the version number and frame size values in order to
guarantee that various revisions of the device cannot incorrectly utilize an internal state
frame that is not valid for that revision.
MC68881/MC68882 USER'S MANUAL FREESCALE
6-31
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