spd6722qcce Intel Corporation, spd6722qcce Datasheet - Page 98

• Manufacturer Part Number: spd6722qcce
• Description: Isa-to-pc-card Pcmcia Controllers
• Manufacturer: Intel Corporation

PD6710/’22 — ISA-to-PC-Card (PCMCIA) Controllers
15.3
15.4
15.4.1
98
Figure 16. DMA Handshake Connections to the ISA Bus
ISA Bus DMA Handshake Signal
A DMA request from the card is passed to the ISA bus as long as the socket interface FIFO is
empty. IRQ10 is used as the DMA request output to the ISA bus when bit 2 of the Misc Control 2
register is ‘1’. When bit 2 of the Misc Control 2 register is ‘1’, IRQ9 is redefined as the active-low
DMA acknowledge input from the ISA bus. This signal must remain active for all DMA transfers
through the PD6722.
to Make the PD6722 DMA-Capable
Terminal counts are passed through to the card from the PD6722 -VPP_VALID pin when bit 6 of
the Misc Control 2 register is ‘1’. For a DMA write process, the last-cycle terminal count
condition is indicated by -OE being active-low during a card DMA data read cycle. For a DMA
read process, terminal count is indicated by -WE being active-low during the last card cycle.
Configuring the PD6722 Registers for a DMA Transfer
Program the registers as follows to configure a PD6722 socket interface for DMA transfer to/from
a DMA-capable PC Card:
Programming the DMA Request Pin from the Card
The PD6722 allows selection of one from three PC Card interface inputs to be redefined as the
DMA request input, and it also allows programming of the active level of the selected input. This is
done by setting bits 7 and 6 of the Extension Control 1 register to the desired values matching
those of the DMA-capable PC Card to be used.
Once this selection of DMA request input is complete, the PC Card interface is configured at the
signal level for DMA card interfacing.
The following table shows how the PD6722 socket interface signals are redefined when a card is in
DMA card interface mode:
1. Select which pin on the PC Card interface will serve as the DMA request input.
2. Configure the socket interface as I/O-capable.
3. Prevent dual-interpretation of socket interface DMA handshake signals.
4. Set the DMA Enable bit.
Bus
ISA
-DACK
DREQ
TC
IRQ10
IRQ9
-VPP_VALID
PD6722
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