Bitfields for Intel 82443BX SDRAM Control Register:
Bit(s) Description )
15-10 reserved (0)
9-8 add one-clock delay to idle/pipeline DRAM leadoff when =01 (all other
values are illegal)
7-5 SDRAM mode select
000 normal operation
001 issue NOP command on all CPU-to-SDRAM cycles
010 issue All-Banks-Precharge command on all CPU-to-SDRAM cycles
011 issue mode register set command on CPU-to-SDRAM cycles
(command is driven on memory address lines, so the proper
address must be calculated for each row of memory to drive
the correct command; MAx[2:0] must be driven to 010 for
burst-of-4 mode, MAx3 to 1 for interleave wrap type,
MAx4 to the value of the CAS# latency bit, MAx[6:5] to 01,
and MAx[12:7] to 0000000
100 issue CBR cycles on all CPU-to-SDRAM cycles
else reserved
4 "SDRAMPWR" specifies how CKE signals are driven for various DRAM
configurations; refer to #01145 bit 5
3 Leadoff Command Timing
=0 four CS# clocks (100 MHz or 66 MHz desktop if MAA/MAB load > 9)
=1 three CS# clocks (66 MHz mobile platforms, or desktop w/ load <= 9)
2 CAS# latency
=0 three DCLKs
=1 two DCLKs
1 SDRAM RAS# to CAS# delay
=0 three clocks
=1 two clocks
0 SDRAM RAS# precharge
=0 three clocks
=1 two clocks
SeeAlso: #01142