W83L517D Datasheet, PDF (107/138 Pages) Winbond – LPC SUPER I/O

W83L517D
6.4 Extension FDD Mode (EXTFDD)
Version 0.6
In this mode, the W83627HF changes the printer interface pins to FDC input/output pins, allowing the
user to install a second floppy disk drive (FDD B) through the DB-25 printer connector. The pin
assignments for the FDC input/output pins are shown in Table 6-1.
After the printer interface is set to EXTFDD mode, the following occur:
(1) Pins MOB# and DSB# will be forced to inactive state.
(2) Pins DSKCHG#, RDATA#, WP#, TRAK0#, INDEX# will be logically ORed with pins PD4-PD0 to
serve as input signals to the FDC.
(3) Pins PD4-PD0 each will have an internal resistor of about 1K ohm to serve as pull-up resistor for FDD
open drain/collector output.
(4) If the parallel port is set to EXTFDD mode after the system has booted DOS or another operating
system, a warm reset is needed to enable the system to recognize the extension floppy drive.
6.5 Extension 2FDD Mode (EXT2FDD)
In this mode, the W83627HF changes the printer interface pins to FDC input/output pins, allowing the
user to install two external floppy disk drives through the DB-25 printer connector to replace internal
floppy disk drives A and B. The pin assignments for the FDC input/output pins are shown in Table6-1.
After the printer interface is set to EXTFDD mode, the following occur:
(1) Pins MOA#, DSA#, MOB#, and DSB# will be forced to inactive state.
(2) Pins DSKCHG#, RDATA#, WP#, TRAK0#, and INDEX# will be logically ORed with pins PD4-PD0 to
serve as input signals to the FDC.
(3) Pins PD4-PD0 each will have an internal resistor of about 1K ohm to serve as pull-up resistor for FDD
open drain/collector output.
(4) If the parallel port is set to EXT2FDD mode after the system has booted DOS or another operating
system, a warm reset is needed to enable the system to recognize the extension floppy drive.
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Publication Release Date: Apr. 2000
Revision 0.60