After Zilog ceased production of the 8-bit Z80 processors on April 15, enthusiasts initiated the creation of an open clone of this processor. The goal of the project is to develop a replacement for the Z80 processors that will be compatible with the original Zilog Z80 CPU, maintaining pin compatibility and usable in the ZX Spectrum computer. Schematics, descriptions of hardware blocks in Verilog, and the necessary production documentation are distributed under the Apache 2.0 license. The production of the first trial batch of FOSS Z80 processors is scheduled for June 2024.
The FOSS Z80 chip development utilizes the OpenROAD framework, which is being developed to automate the open chip design process, as well as the Skywater PDK (Process Design Kit), which describes the 130nm manufacturing process used at the SkyWater factory, allowing for the preparation of the necessary design files for chip production. To reduce costs for the testing and design of the chip, the Tiny Tapeout project infrastructure is being utilized.
The rapid readiness of the chip is due to the fact that instead of designing from scratch, the development used the previously evolving open project TV80, which provides a Verilog description of a core compatible with the Z80 CPU, distributed under the MIT license. After the first batch is produced, the project developers plan to compare the chip with other implementations, such as A-Z80 — an FPGA-based implementation (Altera, Xilinx, and Lattice) supplied under the GPLv2 license, and Z80Explorer — a chip simulator that reproduces the Zilog Z-80 at the electronic circuit level.
The Z80 processor was introduced in 1976 and was produced for 48 years. The chip gained fame through home computers like the ZX Spectrum, gaming consoles like Sega and Game Boy, calculators from Texas Instruments, and its support in the CP/M operating system. Additionally, the Z80 CPU was widely used in industrial equipment, various controllers, modems, cash registers, measuring equipment, and peripheral devices.
Source: opennet.ru
