
80C196KB USER’S GUIDE
This feature gives very simple and flexible ready con-
trol. For example, every slow memory chip select line
could be ORed together and connected to the READY
pin with Internal Ready Control programmed to insert
the desired number of waitstates into the bus cycle.
If the READY pin is pulled low during the CCR fetch,
the bus controller will automatically insert 3 waitstates
into the CCR bus cycle. This allows the CCR fetch to
come from slow memory without having to assert the
READY pin.
Bus Control
Using the CCR, the 80C196KB can generate several
types of control signals designed to reduce external
hardware. The ALE, WR, and BHE pins serve dual
functions. Bits 2 and 3 of the CCR specify the function
performed by these control lines.
Standard Bus Control
If CCR bits 2 and 3 are 1s, the standard bus control
signals ALE, WR, and BHE are generated as shown in
Figure 15-4. ALE rises as the address starts to be driv-
en, and falls to externally latch the address. WR is driv-
en for every write. BHE and MA0 can be combined to
form WRL and WRH for even and odd byte writes.
270651 – 52
16-Bit Bus Cycle
270651 – 53
8-Bit Bus Cycle
Figure 15-4. Standard Bus Control
270651 – 79
Figure 15-5. Decoding WRL and WRH
73
数控原理与维修
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Содержание 80C196KB Series
Страница 1: ...November 1990 80C196KB User s Guide Order Number 270651 003 http www agreenleaf cn...
Страница 59: ...80C196KB USER S GUIDE Figure 11 7 Ideal A D Characteristic 270651 37 55 http www agreenleaf cn...
Страница 60: ...80C196KB USER S GUIDE Figure 11 8 Actual and Ideal Characteristics 270651 38 56 http www agreenleaf cn...
Страница 61: ...80C196KB USER S GUIDE Figure 11 9 Terminal Based Characteristic 270651 39 57 http www agreenleaf cn...
Страница 70: ...80C196KB USER S GUIDE Figure 13 5 Reset Sequence 80C196KB Reset Sequence 270651 45 66 http www agreenleaf cn...
Страница 83: ...80C196KB USER S GUIDE 270651 80 Figure 15 14 AC Timing Diagrams 79 http www agreenleaf cn...
Страница 84: ...80C196KB USER S GUIDE 270651 81 270651 84 Figure 15 14 AC Timing Diagrams Continued 80 http www agreenleaf cn...