
3.0 Device Architecture and Configuration
(Continued)
Revision 1.2
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P
3.9
PARALLEL PORT (PP) CONFIGURATION
3.9.1
The PC8741x Parallel Port supports all IEEE1284 standard communication modes: Compatibility (also known as Standard
or SPP), Bidirectional (known also as PS/2), FIFO, EPP (also known as mode 4) and ECP (with an optional Extended ECP
mode).
The Parallel Port includes two groups of runtime registers, as follows (see Section 10.2 on page 222):
A group of 21 registers at first level offset, sharing 14 entries. Three of this registers (at offsets 403h, 404h and 405h)
are used only in the Extended ECP mode.
A group of four registers, used only in the Extended ECP mode, accessed by a second level offset.
The desired mode is selected by the ECR runtime register (offset 402h). The selected mode determines which runtime reg-
isters are used and which address bits are used for the base address. The FDC functional block registers are shown in
Section 10.2 on page 222. All these registers are V
DD
powered.
General Description
3.9.2
Table 18 lists the configuration registers that affect the Parallel Port. Only the last register (F0h) is described here. See Sec-
tion 3.2.3 on page 40 for descriptions of the other configuration registers. All these registers are V
DD
powered.
Logical Device 1 (PP) Configuration
Table 18. Parallel Port Configuration Registers
Index
Configuration Register or Action
Type
Power Well
Reset
30h
Activate (see Section 3.3.1 on page 43).
R/W
V
DD
00h
60h
Base Address MSB register. Bits 7-3 (for A15-11) are read only, 00000b. Bit 2
(for A10) must be 0b.
R/W
V
DD
02h
61h
Base Address LSB register. Bits 1 and 0 (A1 and A0) are read only, 00b. For ECP
mode 4 (EPP) or when using the Extended registers, bit 2 (A2) must also be 0b.
R/W
V
DD
78h
70h
Interrupt Number and Wake-Up on IRQ Enable register.
R/W
V
DD
07h
71h
Interrupt Type:
Bits 7-2 are read only.
Bit 1 is a read/write bit.
Bit 0 is read only. It reflects the interrupt type dictated by the Parallel Port
operation mode. This bit is set to 1 (level interrupt) in Extended mode and
cleared (edge interrupt) in all other modes.
R/W
V
DD
02h
74h
DMA Channel Select.
R/W
V
DD
04h
75h
Report no second DMA assignment.
RO
V
DD
04h
F0h Parallel Port Configuration register.
R/W
V
DD
F2h