COMMERCIAL AND INDUSTRIAL SWITCHING CHARACTERISTICS AND WAVEFORMS
In the switching waveforms that follow, several
abbreviations are used to indicate the specific periods
of a bus cycle. These periods are referred to as time
states. A typical bus cycle is composed of four
consecutive time states: t1, t2, t3, and t4. Wait states,
which represent multiple t3 states, are referred to as tw
states. When no bus cycle is pending, an idle (ti) state
occurs.
In the switching parameter descriptions, the
multiplexed address is referred to as the AD address
bus; the nonmultiplexed address is referred to as the A
address bus.
Key to Switching Waveforms
WAVEFORM
INPUT
OUTPUT
Must be
Steady
Will be
Steady
May
Will be
Change
Changing
from H to L
from H to L
May
Will be
Change
from L to H
Changing
from L to H
Don’t Care,
Any Change
Permitted
Changing,
State
Unknown
Does Not
Apply
Center
Line is High-
Impedance
Off State
Invalid
Invalid
Am186TMER and Am188TMER Microcontrollers Data Sheet
67
AMD [ AMD ]
