Memotech Limited MTX 500, Service Manual

Page: 10 / 78

6
Z80 CPU
The instruction set contains 158 instructions. The 78
instructions of the 8080A are included as a subset;
8080A software compatibility is maintained.
Eight MHz, 6 MHz, 4MHz and 2.5 MHz clocks for the Z80H,
Z80B, Z80A and Z80 CPU result in rapid instruction
execution with consequent high data throughput.
The extensive instruction set includes string, bit,
byte and word operations. Block searches and block
transfers together with indexed and relative addressing
result in the most powerful data handling capabilities
in the microcomputer industry.
The Z80 microprocessors and associated family of
peripheral controllers are linked by a vectored
interrupt system. This system may be daisy-chained to
allow implementation of a priority interrupt scheme.
Little, if any, additional logic is required for daisy-
chaining.
Duplicate sets of both general-purpose and flag
registers are provided, easing the design and operation
of system software through single-context switching,
background-foreground programming and single-level
interrupt processing. In addition, two 16-bit index
registers facilitate program processing of tables and
arrays.
There are three modes of high-Speed interrupt
processing: 8080 similar, non-Z80 peripheral device
and Z80 Family peripheral with or without daisy chain.
On-chip dynamic memory refresh counter.
MTX Service Manual