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Signal Descriptions
5-14
MPC821FADS-DB USER’S MANUAL
MOTOROLA
47
SDRMCS
SDRMCS
I/O, L
SDRAM Chip-Select signal. CS4 on the
MPC821. Used as chip-select for the
synchronous DRAM. Pulled up. When the
SDRAM is disabled via the BCSR, this signal
can be used off-board via the daughterboard.
48
GND
GND
—
49
GPL3
GPL3
I/O, L
General-Purpose line 3 for UPMA or UPMB.
Used as WR signal for the SDRAM.
50
GND
GND
—
51
GPL2
GPL2
I, L
General-Purpose Line 2 for UPMA or UPMB.
Used with the SDRAM as a CAS signal.
52
GND
GND
—
53
WE3
WE3
I, L
GPCM Write Enable 3 or PCMCIA WE signal.
Selects the LSB within a word for the Flash
SIMM or qualifies writes for a PC card.
54
GND
GND
—
55
WE2
WE2
I, L
GPCM Write Enable 2 or PCMCIA OE signal.
Selects the offset two bytes within a word for
the flash SIMM or open data buffers for read
from PC card.
56
GND
GND
—
57
WE1
WE1
I, L
GPCM Write Enable 1 or PCMCIA I/O Write
signal. Used to qualify write cycles to the flash
memory and as I/O write for the PCMCIA
channel.
58
GND
GND
—
59
BS2A
BS2A
I, L
Byte Select 2 signal for UPMA. Selects offset
two bytes within a word. Used for DRAM
access.
60
GND
GND
—
61
WE0
WE0
I, L
GPCM Write Enable 0 or PCMCIA I/O Read
signal. Used to qualify write cycles to the flash
memory and as I/O reads from the PC card.
62
GND
GND
—
63
SPARE1
SPARE1
I,O, L
Spare line 1. Pulled up, but otherwise unused
on this board.
64
GND
GND
—
65
EDOOE
EDOOE
I,L
EDO Output Enable signal. It is the
general-purpose line 1 for UPMA and UPMB.
Used for output enable with EDO DRAM
SIMMs that have this input (most of them do
not). Used also as RAS signal for the SDRAM.
66
GND
GND
—
67
BS0A
BS0A
I, L
Byte Select 0 signal from UPMA. Selects offset
zero bytes within a word. Used as one of the
CAS lines for DRAM access.
68
GND
GND
—
Table 5-9. PM1 Interconnect Signals (Continued)
PIN
MOTHERBOARD
SIGNAL
DAUGHTERBOARD
SIGNAL
INPUT/
OUTPUT
DESCRIPTION
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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