Theory of Operation
CMOS VERSIONS OF THE ZT 8808A/8809A
The ZT 8808A and ZT 8809A processor boards are also available in
CMOS versions, ZT 88CT08A and ZT 88CT09A, respectively. These
versions provide lower power and extended temperature operation.
Like
the
ZT 8808A
and
ZT 8809A,
the
ZT 88CT08A
and
ZT 88CT09A differ only in their processor clock speeds; they are 5
and 8 MHz, respectively. System level differences between CMOS
versions and non-CMOS versions are discussed briefly here and in
further detail in Chapter 13.
ZT 88CT09A refers to both the
ZT 88CT08A and ZT 88CT09A in the following description except
where explicitly stated otherwise.
Added Features
The ZT 88CT08A and the ZT 88CT09A extend the operating
temperature range to between -40˚ and +85˚ Celsius. All on-board
logic is CMOS and utilizes an advanced speed TTL compatible
CMOS logic family (ACT) to allow support of both CMOS and non-
CMOS STD bus boards. This is an advantage over strictly CMOS
logic (HC or AC), which must receive only CMOS logic levels on its
inputs and is therefore restricted to operation with CMOS boards only.
The ZT 88CT09A does not have this restriction and is named as such
to distinguish both CMOS and TTL compatibility.
Notice the
schematic in the back of this manual references 74ACT family parts;
these are replaced by 74ALS family parts for the ZT 8808A and
ZT 8809A.
In addition to these environmental and electrical advantages, the
ZT 88CT09A contains two added features to support very low power
applications. They are Clock Slowdown and Halt with Interrupt
Restart.
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