Mode 2, Long Read/Write With Early Address - Intel 8XC196NT User Manual

XTAL 1
CLKOUT
T
CHLH
ALE/ADV#
RD#
Bus Read
AD15:0
8- and16-bit
Bus Mode
WR#
Bus Write
AD15:0
8- and 16-bit
Bus Mode
BHE#
AD15:8
INST

14.8.4 Mode 2, Long Read/Write with Early Address

Mode 2 (Figure 14-24) is similar to mode 1 in that RD#, WR#, and ALE begin ½ T
the bus cycle and the widths of RD# and WR# are 1 T
mode 1 in that the address is also placed onto the bus ½ T
timing is 1 T longer, the T
OSC
than in mode 3. This mode trades a longer T
T
OSC
T T
CHCL CLCL
T
CLLL
T
LHLL
T
LLRL
T T
AVLL LLAX
Address
T
AVDV
T
LLWL
Address Out
BHE Valid
AD15:8 Valid 8-bit Bus Mode
INST Valid
Figure 14-23. Mode 1 System Bus Timing
timing is ½ T
AVDV
AVDV
INTERFACING WITH EXTERNAL MEMORY
T
LHLH
T
RLRH
T
RLDV
T
RLAZ
Data In D15:0
T
WLWH
T
QVWH
Data Out
longer than in mode 3. It differs from
OSC
earlier in the bus cycle. The T
OSC
longer, and T is ½ T
OSC RHDZ
for a shorter T .
RHDZ
T
XHCH
T
RHLH
T
RHDZ
T
WHQX
T , T
WHBX RHBX
T , T
WHAX RHAX
T , T
WHIX RHIX
A3098-01
earlier in
OSC
RLDV
shorter in mode 2
OSC
14-37