An attempt to create a tick-based emulator of Z80 and related computers (starting with ZX Spectrum).
Some emulators works at "instruction level". That means that the emulated processor runs an entire instruction (like a LD A,(HL)) in a single atomic operation. When the instruction finishes, the control can return to the caller.
In a tick-based emulator, the "tick" is the smallest operation. An emulated processor instruction can last (and usually do) for more than one tick. For example, in Z80 all instructions last at minimum 4 ticks: 2 ticks for reading the next opcode from memory and 2 ticks more to decode the opcode. If more memory accesses and other I/O operations are necessary, then the instruction can take more ticks to complete. In a tick-based emulator, the control is returned to the caller at each tick, that means you can revert or change the state of the emulated system in the middle of an instruction execution.
In this emulator the communication between the processor (the emulated Z80) and other peripherals (like memory) is modelled by the processor pins (as happen in the real device). So, the only external observable state of the processor are the value of its pins. All peripherals are expected to interact with the Z80 by reading and writing its pins.
WIP, WIP, WIP, WIP. Everything is on WIP
Who knows... This is a pet project, developed in my spare time, so, to be honest, I don't know :)
Start using Allegro for creating the emulator frontend. Idea is to have a dotnet console app that launch an Allegro window with the emulated screen. In 1st versions all emulator-controls will be through the console app probably.
I am using [AllegroDotNet]/(https://github.com/sub-c/AllegroDotNet) for interacting with Allegro. In 1st iterations i will use AllegroDotNet as-is, but I suspect that I will need to add some features to it to handle all my needs... Sure will be a nice trip :)