Signal Summary - Motorola MC68020 User Manual

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