ZLoader and ZIOS

ZLoader really comprises two elements:

• ZIOS - Z80 I/O system. A set of libraries that provide a foundation for building and running other applications
• ZLoader - a user interface and set of tools, including a debugger, to manage the system

ZLoader is a low level 'monitor' programme that can be used to provide a base operating environment for other applications. The code structure is documented along with the code in the zloader directory in the Git repository.

These Wiki pages document how the system works rather than discussions of the code.

The loader provides the following user features:

• a basic command line interface accessed via SIO port A
• an underlying memory management system
• auto-boot code
• ability to load code in to memory from:
  • an Intel hex file pasted from the command line
  • via a block protocol from a Raspberry Pi attached to SIO port B
  • from a suitably formatted SDCard
• A disassembler
• A basic debugger

Topics:

• Command Line
• Boot process
• Memory management
• Services

Status: ZLoader is an evolving application that's grown somewhat along with the hardware. It needs a fairly thorough restructure and simplification so expect changes! There are a number of features that are required but not yet available:

• Code to write to/manage SDCard data (currently it can read data in a specific format)
• Replace the Interrupt Mode 0 (IM0) interrupt model with a mode 2 (IM2) vectored interrupts
• Make use of the CTC
• Add support for the second SDCard