Electronics hobbyist and software developer

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Old games on modern PCs


ZETOS - Zipplet's Embedded Tiny OS

ZETOS is a small OS designed for embedded systems based around the Z80 processor. The OS is designed to be easy to port to different systems, and simple to develop for. ZETOS is a single tasking operating system much like CP/M, with support for TSR-like (Terminate and Stay Resident) modules that can extend functionality known as OSM's (Operating System Module).

What is the target audience of ZETOS?

ZETOS is currently a hobby project, however it is intended to be useful for:

  • Hobby Z80 machines as an alternative to CP/M
  • Embedded Z80 machines (e.g. a home automation controller)
  • Later, an alternative to CP/M due to the development of a CP/M compatibility module

What is the current status of development?

ZETOS is currently in the early prototyping phase. I am developing it along side a hobby Z80 computer. ZETOS will eventually be an open source project.

To see progress on my Z80 computer system, please see my Z80 project page.

What are the minimum requirements?

Currently the minimum requirements are:

  • 64KB of contiguous unbanked RAM (ZETOS lives in the upper half with a vector table in low memory; OSM's load just underneath ZETOS; applications load into lower memory)
  • 8KB of bootstrap ROM that can be switched out once the bootstrap ROM copies itself to RAM
  • 64KB of block storage for the main OS
  • A timer IC such as the Z80 CTC for periodic interrupts; an RTC is not required as it can be simulated by the BIOS
  • 1 serial port for console access provided by an IC such as the Z80 SIO
  • A supervisor IC (such as a high pin count microcontroller) to access block storage or some other method

Devices are accessed via the BIOS which must be ported to each board design. It is designed to be fairly easy to port. The block storage can be anything. The recommended design is to use a small 64-128KB serial EEPROM accessed via a supervisor IC for the main OS, and some other larger form of block storage for application data and files such as an SD card (also accessed via the supervisor IC).

zetos/start.txt · Last modified: 2017/10/01 08:22 UTC by Michael Nixon