User Manual

2.11.1 Definition of an I/O Expansion Bus
The I/O expansion bus of the 7521 series can be divided into 3 groups as
follows:
1. Power supply & reset signals: VCC, GND, RESET, /RESET
2. , Parallel Bus:
• System clock: CLOCKA
• Asynchronous ready control: ARDY
• Address bus: A0 ~ A6, A7 ( 7521 series without A7)
• Data bus: D0 ~ D7
• Interrupt control: INT0, INT1, INT4 ( 7521 series without INT4)
• Chip select & read/write strobe: /CS, /WR, /RD
3. Serial Bus: TO_0, TO_1, TI_0, TI_1, SCLK, DIO9, DIO4, DIO14
Refer to “I/O Expansion Bus for 7188X/7188E User’s Manual” for more information.
7521/2/2A/3/4/7 Series Hardware User’s Manual, Ver. 1.5 Sep/2002, 7Mh-001-15 -----58