CPC700 User’s Manual—Preliminary
2-5
2.3 Memory Interface Signals
Signal Name
Active
Level
I/O
Description
M_DATA[0:63]
High
I/
O
Memory Data: 64-bit memory data bus. If configured for a 32-bit memory
interface, M_DATA[0:31] are used.
ECC[0]
High
I/
O
Error Correction Code Data[0]: Bit [0] of the 8-bit Error correction code
data bus. Bits [1:7] are multiplexed with the DQM bus bits [1:7]. If ECC is
enabled a single DQM (bit 0) is connected to all DQM inputs on all DIMMs.
DQM[0]
High
O
SDRAM Data Mask[0]: Data byte mask bus bit 0. This bit is connected to all
DQM inputs of all DIMMs if ECC is used in the system. If ECC is not used,
then ECC/DQM[1:7] lines make up the remainder of the 8-bit DQM bus.
DQM[0] corresponds to Memory Data Lane 0. During reads, the CPC700
asserts DQM high to cause the SDRAM to tristate the SDRAM output. If
DQM is low, the SDRAM drives the data onto the output.
During writes, DQM high commands the SDRAM to mask the data. The input
data is ignored and the previous contents of the SDRAM are retained. When
DQM is low during a write, the SDRAM data is updated as usual.
ECC/DQM[1:7]
High
I/
O
ECC[1:7] / DQM[1:7]: Multiplexed ECC and DQM bit [1:7]. The use of either
ECC or the additional DQM lines are governed by a pin strapping option.
DQM7 corresponds to Memory Data Lane 7
MA[12:0]
High
O
Memory Address[12:0]: Memory address bus. Memory address bit 10 also
functions as the auto-precharge bit. Signal range is in little endian notation.
BANK_SEL_N
[0:4]
Low
O
Memory Bank Select[0:4]: Five Banks are supported with bank 0 required
to contain the boot ROM device. The remaining 4 banks may be programmed
for SDRAM, ROM/Flash, SRAM, or peripheral devices.
WE_N Low
O
Write Enable: SDRAM Write Enable.
CKE
High
O
Clock Enable: SDRAM Clock Enable.
RAS_N
Low
O
Row Address Strobe: SDRAM Row Address Strobe.
CAS_N
Low
O
Column Address Strobe: SDRAM Column Address Strobe.
BA[1:0]
High
O
Bank Address[1:0]: SDRAM Bank Address. The Bank Address accesses
one of up to 4 internal banks within an SDRAM chip. Signal range is in little
endian notation.
ROM_OE_N
Low
O
ROM Output Enable: Output enable for ROM / Peripheral devices.
ROM_WE_N
Low
O
ROM Write Enable: Write enable for ROM / Peripheral devices.
ROM_RD_N
Low
O
ROM Read: Read signal for ROM / Peripheral devices.
ROM_WR_N
Low
O
ROM Write: Write signal for ROM / Peripheral devices.
ROM_RNW High
O
ROM Read-Not-Write: The ROM_RNW signal may be used as a direction
indicator for external data bus transceivers in the event that the system
designer chooses to isolate the ROM / Peripheral bus from the SDRAM data
bus.
Содержание CPC700
Страница 1: ...CPC700 Memory Controller and PCI Bridge User s Manual Version 1 1 Issue Date 3 22 00 Preliminary...
Страница 10: ...Table of Contents x Table of Contents...
Страница 16: ...Tables xvi List of Tables...
Страница 28: ...1 12 CPC700 User s Manual Preliminary...
Страница 72: ...3 36 Processor Interface...
Страница 132: ...4 60 Memory Controller...
Страница 184: ...5 52 PCI Interface...
Страница 194: ...6 10 Clock Power Management and Reset...
Страница 224: ...8 18 IIC...
Страница 244: ...10 10 Interrupt Controller...
Страница 246: ...I 11 2 JTAG...
Страница 250: ...12 4 Processor Local Bus PLB...
Страница 262: ...14 10 Register Summary...
Страница 267: ...CPC700 User s Manual Preliminary...