FPGA Z8 Encore Project

[rstofer]

The July 2017 edition of Nuts and Volts magazine has an article re: creating an FPGA CPU similar to the Zilog Z8 Encore device.

Although the Z8 instruction set is similar to the Z80, the architecture is entirely different.  Among other things, the design is based on a Harvard architecture with separate program and data memory areas.  This is important because it allows the FPGA version to queue up instruction bytes (8 byte queue) such that all 4 bytes of long instructions are likely to be immediately available rather than having to fetch on demand.

Code for the CPU can be written using Zilog's free toolchain which includes an assembler and C compiler.

The FPGA is based on an Altera miniboard:
http://www.ebay.com/itm/Altera-EP4CE6E22C8N-Mini-FPGA-Board-Cyclone-IV/112023254939

This might be a very nice advanced beginner project.

It's important to understand that the Z8 is not a Z80, the Z8 is more like an advanced PIC or ATmega.  It has a bunch of peripherals internal to the chip so it isn't just a stand-alone CPU.

[Elf]

Very neat!

I still use the Z8 Encore XP as well as eZ80, occasionally. It was my second microcontroller after PIC, and I think they are still decent chips today although the software libraries are not as extensive as some other manufacturers. Sort of amazing that Zilog is still around after all these years, but apparently they are big into alarm sensor products? (Motion detectors, etc.)