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MC68EN302 Module Bus Controller
2-6
MC68EN302 REFERENCE MANUAL
MOTOROLA
2.7 PARITY CONTROL AND STATUS REGISTER (PCSR)
This register controls and gives the status of the parity checking portions of the parity
circuitry. This register is set to 0x0000 upon hardware reset.
PIE—Parity Error Interrupt Enable. This bit determines if an interrupt is generated when a
parity error is detected.
0 = No interrupt is generated.
1 = Either a level 3 or level 5 interrupt is generated, depending upon the encoding of
the MIL bit in the IER register.
OPAR—Odd Parity. This bit is used to determine if odd or even parity is used.
0 = Parity is even.
1 = Parity is odd.
PEC—Parity Error Chip Selects (PEC3–PEC0). These status bits indicate that there was a
parity error in the corresponding Chip Select Bank. If one of the three bits is set to one, a
parity error is detected in the corresponding bank. If the PIE bit is set, a level 5 (or 3) interrupt
is driven to the processor as long as one of the PEC3–PEC0 bits are set. PEC3–PEC0 are
sticky bits which are cleared when a one is written to them or upon hardware reset. Writing
a zero does not change the value of the PEC bits. The PARITYE pin is asserted until the
PEC3–PEC0 bits are all cleared.
NOTE
If the Parity Pin Enable bit (PPE in MBC CSR) = 0 and parity is
enabled with CSPE in CSER3–CSER0, then a parity error will be
reported on the associated PEC bit.
PED—Parity Error DRAM (PED1–PED0). These status bits indicate that there was a parity
error in the corresponding DRAM bank. If one of the two bits is set to one, a parity error is
detected in the corresponding bank. If the PIE bit is set, a level 5 (or 3) interrupt is driven to
the processor as long as one of the PED bits is set. PED are sticky bits which are cleared
when a one is written to them or upon hardware reset. Writing a zero does not change the
value of the PED bits. Writing a zero does not change the value of the PED bits. The
PARITYE pin is asserted as long as a PED bit is set.
NOTE
If the Parity Pin Enable bit (PPE in MBC CSR) = 0 and parity is
enabled on the DRAM interface (PE1 and/or PE0 = 1 in DCR)
then a parity error will be reported on PED1–PED0.
PIV—Parity Error Interrupt Vector (PIV7–PIV0). If the PIE bit is set, a parity error generates
a level 5 (or 3) interrupt. The PIV bits determine what interrupt vector is returned in response
to a level 5 (or 3) parity error interrupt.
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14
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12
11
10
9876543210
PIE
OPAR PEC3 PEC2 PEC1 PEC0 PED1 PED0
PIV7
PIV6
PIV5
PIV4
PIV3
PIV2
PIV1
PIV0