PARALLEL PORT FLOPPY DISK CONTROLLER
The following parallel port pins are read as
In this mode, the Floppy Disk Control signals
are available on the parallel port pins. When
this mode is selected, the parallel port is not
available. There are two modes of operation,
PPFD1 and PPFD2. These modes can be
selected in the Parallel Port Mode Register, as
defined in the Parallel Port Mode Register,
Logical Device 3, at 0xF1. PPFD1 has only
drive 1 on the parallel port pins; PPFD2 has
drive 0 and 1 on the parallel port pins.
follows by a read of the parallel port register:
1. Data Register (read) = last Data Register
(write)
2. Control Register read as "cable not
connected" STROBE, AUTOFD and SLC =
0 and nINIT =1
3. Status Register reads: nBUSY = 0, PE = 0,
SLCT = 0, nACK = 1, nERR = 1.
The following FDC pins are all in the high
impedence state when the PPFDC is actually
selected by the drive select register:
When the PPFDC is selected the following pins
are set as follows:
1. nPDACK: high-Z
2. PDRQ: not ECP = high-Z, ECP & dmaEn =
0, ECP & not dmaEn = high-Z
3. PINTR: not active, this is hi-Z or Low
depending on settings.
1. nWDATA, DENSEL, nHDSEL, nWGATE,
nDIR, nSTEP, nDS1, nDS0, nMTR0,
nMTR1.
2. If PPFDx is selected, then the parallel port
can not be used as a parallel port until
"Normal" mode is selected.
Note:
nPDACK, PDRQ and PINTR refer to
the nDACK, DRQ and IRQ chosen for
the parallel port.
The FDC signals are muxed onto the Parallel
Port pins as shown in Table 46.
109
SMSC [ SMSC CORPORATION ]
