Integrated Technology Express, Inc.
Jun. 12, 2001
When the battery is installed on motherboard or the ATX power connector is plugged in the
motherboard, the bouncing glitches may be generated on 鈥淰BAT鈥?(from battery) or 鈥?VSB鈥?/div>
(from ATX power supply). Such kind of bouncing glitches may cause the initialization of
鈥淓nvironment Controller Configuration Registers鈥?of IT8700F to be unstable.
For preventing any abnormal behaviors of IT8700F, to program some bits of 鈥淓nvironment
Controller Configuration Registers鈥?to suitable value, after power-on and before POST
sequence, is necessary (We may call it as an 鈥淓arly I/O initialization鈥?sequence.).
The registers which should be programmed to suitable values in the Early I/O
initialization are described as follows;
Environment Controller Configuration Registers (LDN=04h):
Index F0h = 00h
Index F1h = 00h
Index F2h = 00h
Index F3h = 00h
Index F4h = 00h
Index F5h = 00h (Especially, must Bit 7~6 = 00)
By the way, please also set
LDN0, Index F1h/ Bit 7 = 1
LDN3, Index F0h/ Bit 3 = 1 (If the POST Data Port function is used, please
still set LDN3/IndexF0/Bit3 to 1 after POST.)
Moreover, for 720K floppy diskette, please set
LDN5, Index 2Bh = F0h
LDN5, Index 2Ch = 08h
And set FIFO threshold of FDC to 0Fh.
ITTM-AN-01019
By : Moses
Check : Gary
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