Motorola MC68020 - Signal Summary

3- 8 M68020 USER’S MANUAL MOTOROLA
3.13 SIGNAL SUMMARY
Table 3-2 provides a summary of the characteristics of the signals discussed in this
section. Signal names preceded by an asterisk (*) are implemented in the MC68020 and
not implemented in the MC68EC020.
Table 3-2. Signal Summary
Signal Function Signal Name Input/Output Active State Three-State
Function Codes FC2–FC0 Output High Yes
Address Bus
MC68020
MC68EC020
A31–A0
A23–A0
Output High Yes
Data Bus D31–D0 Input/Output High Yes
Transfer Size SIZ1, SIZ0 Output High Yes
*Operand Cycle Start OCS Output Low No
*External Cycle Start ECS Output Low No
Read/Write R/W Output High/Low Yes
Read-Modify-Write Cycle RMC Output Low Yes
Address Strobe AS Output Low Yes
Data Strobe DS Output Low Yes
*Data Buffer Enable DBEN Output Low Yes
Data Transfer and Size Acknowledge DSACK1, DSACK0 Input Low —
Interrupt Priority Level IPL2–IPL0 Input Low —
*Interrupt Pending IPEND Output Low No
Autovector AVEC Input Low —
Bus Request BR Input Low —
Bus Grant BG Output Low No
*Bus Grant Acknowledge BGACK Input Low —
Reset RESET Input/Output Low No**
Halt HALT Input/Output Low No**
Bus Error BERR Input Low —
Cache Disable CDIS Input Low —
Clock CLK Input — —
Power Supply V
CC
Input — —
Ground GND Input — —
*This signal is implemented in the MC68020 and not implemented in the MC68EC020.
** Open-drain