Bitfields for Intel 82437VX,82439HX/TX DRAM extended control register: Bit(s) 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: 82439HX: 82439TX: 00 reserved 00 8mA 00 10mA/10mA (MA/MWE#) 01 10mA (default) 01 8mA/12mA (MAA/MWE#) 01 10mA/16mA (MA/MWE#) 10 16mA 10 12mA/8mA (MAA/MWE#) 10 16mA/10mA (MA/MWE#) 11 reserved 11 12mA 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 SeeAlso: #01099,#01108,#01098,#01116