Memotech Limited MTX 500, Service Manual

Page: 14 / 78

10
Z80 CTC
The Z-80 CTC four-channel counter/timer can be
programmed by system software for a broad range of
counting and timing applications. The four
independently programmable channels of the Z-80 CTC
satisfy common microcomputer system requirements for
event counting, interrupt and interval timing, and
general clock rate generation.
System design is simplified because the CTC connects
directly to both the Z-80 CPU and the Z-80 SIO with no
additional logic. In larger systems, address decoders
and buffers may be required.
Programming the CTC is straightforward: each channel
is programmed with two bytes; a third is necessary when
interrupts are enabled. Once started, the CTC counts
down, reloads its time constant automatically, and
resumes counting. Software timing loops are completely
eliminated. Interrupt processing is simplified because
only one vector need be specified; the CTC internally
generates a unique vector for each channel.
The Z-80 CTC requires a 5 V power supply and
the standard Z-80 single-phrase system clock. It is
fabricated with n-channel silicon-gate depletion-load
technology, and packaged in a 28-pin plastic or ceramic
DIP.
MTX Service Manual