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Bitfields for Intel 82437VX,82439HX/TX DRAM extended control register

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Bit Description

7

reserved

6

(VX/TX) refresh RAS# assertion length
0 = 4 clocks
1 = 5 clocks

5

(VX/TX) Fast EDO Path Select

4

Speculative Leadoff Disable

3

(82439HX) Turn-Around Insertion Enable
1 = insert one extra clock of turnaround time after asserting MWE#

2 - 1

Memory Address Drive Strength 
82437VX: 
00 = reserved
01 = 10mA (default)
10 = 16mA
11 = reserved

82439HX: 
00 = 8mA
01 = 8mA/12mA (MAA/MWE#)
10 = 12mA/8mA (MAA/MWE#)
11 = 12mA

82439TX:
00 = 10mA/10mA (MA/MWE#)
01 = 10mA/16mA (MA/MWE#)
10 = 16mA/10mA (MA/MWE#)
11 = 16mA/16mA (MA/MWE#)

0

 (82437VX) DRAM Symmetry Detect Mode (used to force some memory address lines to fixed value for detecting DRAM symmetry row-by-row)

0

 (82439HX) 64MBit Mode Enable
1 = enable support for 64M SIMMs

0

 (82439TX) reserved

See Also:

 #01099,#01108,#01098,#01116