System Integration Module (SIM60)
MOTOROLA
MC68360 USER’S MANUAL
6-47
NOTE
The table is true for the case SIZM=1.
Breakpoint will be asserted ONLY if the programmed address is
actually accessed.
Table 6-7 shows which combinations of A0-A1 and SIZ1-SIZ0, on eitherthe external bus or
the IMB bus, assert the BKPT pin.
NEG—Negative Breakpoint Match
This bit allows the breakpoint match to occur, using negative address matching logic,
when a block address is selected. If this bit is set, the rest of the address and address
match logic define when a breakpoint match is notto occur. The R/W, size, and FC com-
pare logic are not affected by the NEG bit.
0 = Assert a breakpoint when the memory cycle matches the programmed values.
1 = Assert a breakpoint when the memory cycle does notmatch the programmed block
address. NEG is ignored if the MA bits are 00.
MA1–MA0—Mask Address
The address mask bits allow the breakpoint logic to assert the breakpoint on a memory
block boundary.
00 = No address bits are masked, 32 address bits are compared.
01 = Mask address bits 10–0; the block size is 2K.
10 = Mask address bits 12–0; the block size is 8K.
11 = Mask address bits 14–0; the block size is 32K.
NOTE
Using the NEG bit, the breakpoint can be asserted for accesses
that fall into the block range or for those that fall out of the block
range.
AS8–AS0—Address Space Bits
The address space field allows particular address spaces (function code combinations) to
be masked during the breakpoint match decision. If an address space is masked, an ac-
cess to this space will NOT assert the BKPT pin. To ignore function codes in the break-
point match decision, program these bits to zero. The address space bits are:
AS8—Mask DMA space address space (FC3–FC0 = 1xxx)
AS7—Mask CPU space address space (FC3–FC0 = 0111)
AS6—Mask supervisor program address space (FC3–FC0 = 0110)
AS5—Mask supervisor data address space (FC3–FC0 = 0101)
AS4—Mask [Motorola reserved] address space (FC3–FC0 = 0100)
AS3—Mask [user reserved] address space (FC3–FC0 = 0011)
AS2—Mask user program address space (FC3–FC0 = 0010)
AS1—Mask user data address space (FC3–FC0 = 0001)
AS0—Mask [Motorola reserved] address space (FC3–FC0 = 0000)