ward compatibility with existing ZiLOG Z80 devices. The
er-saving modes, and EMI noise reduction.
鈩?/div>
design also incorporates additional
feature enhancements to the ASCIs, DMAs, and
56#0&$;
mode power consumption. With the addition of ESCC-like
Baud Rate Generators (BRGs), the two ASCIs offer the flex-
ibility and capability to transfer data asynchronously at rates
of up to 512 Kbps. In addition, the ASCI receiver features
a 4-byte first in/first out (FIFO) buffer which reduces the
likelihood of overrun errors. The DMAs have been modified
to allow for chain-linking of the two DMA channels when
set to take their DMA requests from the same peripherals
device. This feature allows for nonstop DMA operation be-
tween the two DMA channels.
Not only does the Z8S180/Z8L180 consume less power dur-
ing normal operations than the previous model, it offers
three modes intended to further reduce power consumption.
Power consumption during
56#0&$;
Mode is reduced to
10
碌A(chǔ)
by stopping the external oscillators and internal
clock. The
5.''2
mode reduces power by placing the CPU
into a stopped state, consuming less current while the on-
chip I/O devices still operate. The
5;56'/ 5612
mode
places both the CPU and the on-chip peripherals into a
stopped mode, reducing power consumption even further.
A new clock-doubler feature in the Z8S180/Z8L180 allows
the internal clock speed to be twice the external clock speed.
As a result, system cost is reduced by allowing the use of
lower-cost, lower-frequency crystals.
The Enhanced Z180 is housed in 80-pin QFP, 68-pin PLCC,
and 64-pin DIP packages.
0QVG
All Signals with an overline are active Low. For exam-
ple: B/W, in which WORD is active Low; or B/W, in
which BYTE is active Low.
&5</2
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