ST18-AU1 STMICROELECTRONICS [STMicroelectronics], ST18-AU1 Datasheet - Page 8

• Manufacturer Part Number: ST18-AU1
• Description: SIX-CHANNEL DOLBY AC3/MPEG2 AUDIO DECODER
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST18-AU1
Table 2.2
Table 2.3
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Pin name
ED0-15
EA0-15
EIRD
EIWR
XBSE
EYRD
EYWR
XRDE_EXRD
XWRE_EXWR
Pin name
P0-7
Direct X bus extension / Bus extension through bus switch unit (39 pins)
General purpose parallel port (8 pins)
Type
Type
I/O
I/O
O
O
O
O
O
O
O
O
Description
Bus switch unit (BSU) X/Y/I data extension bus.
BSU X/Y/I address extension bus.
BSU I-extension bus read strobe EIRD output.
BSU I-extension bus write strobe EIWR output.
X_extension bus data strobe (BSU not used).
BSU Y-extension bus read strobe EYRD output.
BSU Y-extension bus write strobe EYWR output.
Multiplexed output.
In direct X-bus extension mode (BSU not used):
X-extension bus read strobe (XRDE). Active low when reading from exter-
nal X-memory.
In X extension through BSU mode:
BSU X-extension bus read strobe (EXRD). Active low when reading from
external memory (when bit I/M of XER register is ‘1’: Intel mode).
BSU extension bus data strobe (EDS). Active low when reading from or writ-
ing to external memory (when bit I/M of XER register is ‘0’ Motorola mode).
Multiplexed output.
In direct X-bus extension mode (BSU not used):
X-extension bus write strobe (XWRE). Active low when writing to external
X-memory.
In X extension through BSU mode:
BSU X-extension bus write strobe (EXWR). Active low when writing to ex-
ternal memory (when bit I/M of XER register is ‘1’: Intel mode).
Extension bus read /write signal (ERD_WR). Low during write cycle, other-
wise high (when bit I/M of XER register is ‘0’: Motorola mode).
Description
Parallel port I/O. Each pin can be programmed as input or output.
On reset, all pins are inputs.