ZT 88CT08A/88CT09A CMOS Boards
FUNCTIONAL DIFFERENCES
Logic Family (CT vs. C)
There are two main logic families to choose from when using fast
CMOS logic: CMOS with TTL-compatible inputs and CMOS with
CMOS-compatible inputs.
If your system uses CMOS logic with other CMOS logic, the inputs
need only be CMOS-compatible. Such parts are designated by a "C"
in the device name; for example, 74AC573. On the other hand, if
your system uses CMOS logic with TTL logic as well, the CMOS
logic must have TTL-compatible inputs to guarantee proper logic
levels seen from the TTL devices. These parts are designated by a
"CT" in the middle of the device name (for example, 74ACT573), and
they are compatible with both CMOS and TTL logic input levels.
Both the "C" and the "CT" part types drive CMOS logic levels on the
output.
The ZT 88CT08A/88CT09A are so named to indicate that the logic
family used is CMOS with TTL-compatible inputs (CT). The boards
may be used with any fully CMOS STD bus boards, as well as with
all existing STD-80 compatible non-CMOS boards. All "ALS" family
logic devices on the non-CMOS version of this board are replaced by
"ACT" devices for the ZT 88CT08A and ZT 88CT09A. The bipolar
LSI devices such as the Interrupt Controller and Counter/Timers are
replaced by CMOS versions, as are the PAL devices. The 16C452 and
the RS-232-C serial drivers and receivers are CMOS on all versions
of the ZT 8808A and ZT 8809A.
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