3-30
Computer Group Literature Center Web Site
PCCchip2
3
SCC Receive Interrupt Control Register
IL2-IL0
Interrupt Request Level. These three bits select the
interrupt level for SCC Receive Interrupt. Level 0 does
not generate an interrupt.
AVEC
When this bit is high, the PCCchip2 supplies the interrupt
vector to the MPU during an IACK for SCC receive
interrupt. When this bit is low, the PCCchip2 obtains the
vector from the SCC and passes it to the MPU. The use of
the AVEC mode is not recommended.
IEN
Interrupt Enable. When this bit is high, the interrupt is
enabled. The interrupt is disabled when this bit is low.
IRQ
Interrupt Status. This status bit reflects the state of the
SCC-IRQ3 pin of the CD2401 (qualified by the IEN bit).
When this bit is high, an SCC receive interrupt is being
generated at the level programmed in IL2-IL0 (if
nonzero). This status bit does not need to be cleared,
because it is not edge-sensitive.
SC1-SC0
Snoop Control. These control bits determine the value that
the PCCchip2 drives onto the local MC68040 bus SC1
and SC0 pins, when the CL-CD2401(SCC) performs
DMA accesses. During SCC DMA, when bit SC0 is 0,
Local Bus pin SC0 is low, and when bit SC0 is 1, pin SC0
is high. The same relationship holds true for bit and pin
SC1. See the M68040 and MC68060 user’s manuals for
details on how it uses the Snoop Control signals.
Note
On the MVME177P, which uses only SC1, the SC0 bit must
be 0.
ADR/SIZ
$FFF4201F (8 bits)
BIT
7
6
5
4
3
2
1
0
NAME
SC1
SC0
IRQ
IEN
AVEC
IL2
IL1
IL0
OPER
R/W
R/W
R
R/W
R/W
R/W
R/W
R/W
RESET
0 PL
0 PL
X
0 PL
0 PL
0 PL
0 PL
0 PL
Summary of Contents for MVME1X7P
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Page 90: ...1 64 Computer Group Literature Center Web Site Programming Issues 1 ...
Page 248: ...3 50 Computer Group Literature Center Web Site PCCchip2 3 ...
Page 286: ...4 38 Computer Group Literature Center Web Site MCECC Functions 4 ...
Page 288: ...A 2 Computer Group Literature Center Web Site Summary of Changes A ...
Page 316: ...Index IN 14 Computer Group Literature Center Web Site I N D E X ...