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11−3
11.3 Command Register
The command register provides control over the PCI7x21/PCI7x11 interface to the PCI bus. All bit functions adhere
to the definitions in the PCI Local Bus Specification, as seen in the following bit descriptions. See Table 11−2 for a
complete description of the register contents.
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name Command
Type R R R R R RW R RW R RW R RW R RW RW R
Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Register: Command
Offset: 04h
Type: Read/Write, Read-only
Default: 0000h
Table 11−2. Command Register Description
BIT FIELD NAME TYPE DESCRIPTION
15−11 RSVD R Reserved. Bits 15−11 return 0s when read.
10 INT_DISABLE RW
INTx disable. When set to 1, this bit disables the function from asserting interrupts on the INTx signals.
0 = INTx
assertion is enabled (default)
1 = INTx
assertion is disabled
9 FBB_ENB R
Fast back-to-back enable. The flash media interface does not generate fast back-to-back transactions;
therefore, bit 9 returns 0 when read.
8 SERR_ENB RW
SERR enable. When bit 8 is set to 1, the flash media interface SERR driver is enabled. SERR can be
asserted after detecting an address parity error on the PCI bus.
7 STEP_ENB R
Address/data stepping control. The flash media interface does not support address/data stepping;
therefore, bit 7 is hardwired to 0.
6 PERR_ENB RW
Parity error enable. When bit 6 is set to 1, the flash media interface is enabled to drive PERR response
to parity errors through the PERR
signal.
5 VGA_ENB R
VGA palette snoop enable. The flash media interface does not feature VGA palette snooping;
therefore, bit 5 returns 0 when read.
4 MWI_ENB RW
Memory write and invalidate enable. The flash media controller does not generate memory write
invalidate transactions; therefore, bit 4 returns 0 when read.
3 SPECIAL R
Special cycle enable. The flash media interface does not respond to special cycle transactions;
therefore, bit 3 returns 0 when read.
2 MASTER_ENB RW
Bus master enable. When bit 2 is set to 1, the flash media interface is enabled to initiate cycles on the
PCI bus.
1 MEMORY_ENB RW
Memory response enable. Setting bit 1 to 1 enables the flash media interface to respond to memory
cycles on the PCI bus.
0 IO_ENB R
I/O space enable. The flash media interface does not implement any I/O-mapped functionality;
therefore, bit 0 returns 0 when read.