By Hi-Tech Software. ANSI. Freely available. Includes compiler, assembler, linker, librarian and debugger, library source code.
Hi-Tech Software was acquired by Microchip Technology in 2009 and most of the assets don't seem to be available any more.
Text copied from the website
HI-TECH C compiler for Z80/Z180 Architecture HI-TECH C for Z80/Z180
HI-TECH C for Z80/Z180 offers a complete ANSI C embedded compiler package with a full development system for language C and assembler. HI-TECH C supports the 64K memory model for the base Z80, plus the expanded memory on the Z180 and 64180, or even user-defined banked memory on any other Z80 device, allowing a megabyte of program memory. Interrupt functions can be defined entirely in C, including mode 2 vectors, and I/O ports are mapped as C variables with the port qualifier.
The classic Z80 microprocessor is alive and well, embedded in numerous microcontrollers from several manufacturers. HI-TECH C for Z80/Z180 is a mature, reliable tool backed by 18 years of continuous development.
Compiler Features:
- ANSI C, supporting all standard data types
- Unlimited number of source files
- Multiple optimization levels
- Comprehensive library with source code
- Floating point support (32-bit)
- Mixed C and assembler programming
- Listings showing generated assembler
- Optimizing assembler
- Full linker, with overlaying of vocal variables to minimize RAM usage
- Remote source-level debugger for low-cost in-target debugging included at no extra cost
Embedded Development Environment
HI-TECH C for Z80/Z180 an be run entirely from the HI-TECH Professional Development environment. This environment allows you to manage all of your Z80 projects. You can compile, assemble and link your embedded application with a single step.
Optionally, the compiler may be run directly from the command line, allowing you to compile, assemble and link using one command. Processors Supported: HI-TECH C compiler supports all the Z80/Z180 microcontroller families.