Freescale Semiconductor MC68881 - Move Control Register Instruction Dialog

7
When any of these conditions occurs, the dialog shown in Figure 7-20 applies. Otherwise,
when the operand data format is single, double, or extended, the MC68882 issues the
evaluate <ea> and transfer
data primitive with CA=0 instead of CA= 1. Figure 7-21 shows
the MC68882 dialog.
MC68020/MC68030
MCB8882
ii°
_ ~ ~ ~ ~ =
C0NW~T / i I ~ w t
L---.--J L----J L----J
Figure 7-21. MC68882 Register-to-External Instruction Dialog (S, D, and X Formats)
7.5.1.4 MOVE CONTROL REGISTERS (OPCLASS 100 and 101). This dialog is utilized for
the move single or multiple floating-point system control registers instructions. The dialog
for this instruction type is shown in Figure 7-22. The first primitive of the dialog requests
that the main processor evaluate the effective address and transfer the appropriate number
of bytes to or from the operand CIR. The read of the first primitive causes the response
CIR encoding to be changed to the null primitive, thus avoiding spurious request primitives
in non-MC68020 or non-MC68030 based systems. When the transfer data primitive service
is complete, the main processor is released to begin execution of the next instruction. Note
g E
I | I --l*| ----
L I I I I L__J L__J I I
. ~ ".---__---.---.---.--. =-
~ ~ I R I W ] R I W I R I W Ic~
~ ~ ' , , ,_
A ~ (DR=O)
Figure 7-22. Move Control Register Instruction Dialog
FREESCALE
7-26
MC68881/MC68882 USER'S MANUAL