82091AA Datasheet, PDF (88/204 Pages) Intel Corporation – ADVANCED INTEGRATED PERIPHERAL (AIP)

82091AA
6 2 Parallel Port Operations
The parallel port can be placed in ISA-Compatible
PS 2-Compatible or EPP mode by hardware config-
uration or by writing to the 82091AA’s configuration
registers (PCFG1 Register) If access to the configu-
ration registers is not disabled by hardware configu-
ration a hardware configured parallel port mode can
be changed by programming the PCFG1 Register
ECP mode is entered by programming the ECP Ex-
tended Control Register (ECR) Writing to this regis-
ter changes any previously selected parallel port
mode (via hardware configuration or writing the
PCFG1 Register) to one of the ECP ECR Register
modes selected via ECR 7 5 Note that ECP mode
cannot be entered by hardware configuration or pro-
gramming the 82091AA configuration registers
6 2 1 ISA-COMPATIBLE AND PS 2-
COMPATIBLE MODES
The ISA-Compatible mode is used for standard ISA-
type parallel port interfaces Figure 39 shows the
parallel port interface for ISA-Compatible mode
STROBE AUTOFD INIT and SELECTIN
are controlled by software via the PCON Register
and the status of SELECT PERROR FAULT
ACK and BUSY are reported in the PSTAT Regis-
ter PD 7 0 are outputs only Note that for a reverse
data transfer using the Nibble protocol the peripher-
al device supplies data 4 bits at a time using the
BUSY SELECT PERROR and FAULT signals
Figure 39 ISA-Compatible Mode
290486 – 39
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