DMA to AT-Bus, On-Board I/O, and ROM
Tables 12-34 through 12-36 shows the DMA to AT bus, on-board I/O, and ROM
accesses.
Table 12-34.
197DMA to AT-Bus, On-Board I/O, and ROM----Output Responses
Symbol
Parameters
Min.
Max.
t190
-DACKn or -DACKEN delay from BUSCLK rise
----
46
t191
ALE rise from HLDA rise
----
70
t192
DMA Address delay from BUSCLK rise.
Note: DMA address refers to A0-23, MODA0, MODA20, and -BHE
----
35
t194
Command fall from BUSCLK rise
----
40
t195
Command rise from BUSCLK rise
----
40
t197
TC rise from BUSCLK rise
----
40
t198
TC fall from BUSCLK rise
----
35
t199
LOMEGCS delay from A16-23
----
35
t200
HOLD delay from PROCCLK rise at start of T-state
5
25
t201
DSELA, B delay from OSC2 rise (MRA mode)
----
35
t202
DACKA, B, C valid before DACKEN fall
(MRA mode)
0
----
t203
DACKA, B, C hold after DACKEN rise (MRA mode)
0
----
Table 12-35.
DMA to AT-Bus, On-Board I/O, and ROM----Formula Specifications
Symbol
Critical Path
Formula
Max.
te194
Command low time
t194-t195
10
te195
Command high time
t195-t194
10
Table 12-36.
DMA to AT-Bus, On-Board I/O, and ROM----Input Requirements
Symbol
Parameters
Min.
Max.
t210
HLDA setup before BUSCLK rise
DREQ setup before BUSCLK rise
DREQ hold after BUSCLK rise
IOCHRDY setup before BUSCLK rise
IOCHRDY hold after BUSCLK rise
15
----
t212
15
----
t213
15
----
t214
10
----
t215
5
----
These parameters are nonrestrictive. The signal may not be recognized until the subsequent clocking
parameters are violated. The parameter specifies only the condition needed to guarantee recognition
a particular clock edge.
period if these
of the signal on
I
AC Characteristics 25MHz
System Characteristics
12-18
Revision 3.0
P R E L I M I N A R Y
Chips and Technologies, Inc.