Xilinx CAST CZ80CPU User Manual

Xilinx CAST CZ80CPU User Manual


8-Bit Microprocessor


The CZ80CPU implements a fast, fully-functional, single-chip, 8-bit microprocessor with the same instruction set as the Z80.

The core has a 16-bit address bus capable of directly accessing 64kB of memory space. It has 252 root instructions with the reserved 4 bytes as prefixes, and accesses an additional 308 instructions.

The microcode-free design was developed for reuse in ASIC and FPGA implementations. It is strictly synchronous, with no internal tri-states and a synchronous reset.


The CZ80CPU is suitable for many embedded controller applications, including:

industrial control systems

point-of-sale terminals

automotive controls

Block Diagram

Programming features contain 208 bits of read/write memory that are accessible to the programmer.

The internal registers include an accumulator and six 8-bit registers that can be paired as three 16-bit registers.

In addition to general registers, a 16-bit stack-pointer, 16-bit program-counter, and two 16-bit index registers are provided.

Control Unit

o 8-bit Instruction decoder

Arithmetic-Logic Unit

o 8-bit arithmetic and logical operations

o 16-bit arithmetic operations o Boolean manipulations

Register File Unit

o Duplicate set of both general purpose and flag registers

o Two 16-bit index registers

Interrupt Controller

o Three modes of maskable interrupts

o Non maskable interrupt

External Memory interface

o Can address up to 64 KB of program memory

o Can address up to 64 KB of data memory

o Can address up to 64 KB of input/output devices

On-core dynamic memory refresh counter


The core can be used as an equivalent of the Zilog™ Z80, which due to its popularity has a variety of industry certified software ready to be used

Easy implementation in SoC designs targeted to FPGAs or ASICs

Guarantees independence from chip vendors

October 2012

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