Z80-based computers

Hey Lains, I've just relatively recently got into electronic DIY stuff and I've decided that my next project is going to be some kind of Z80 based computer. Maybe even ZX Spectrum clone. I've slowly started ordering parts from China (I'm definitely not paying 50 cents+ per IC, if I can get 10 from China for like 80 cents). I plan to build that $4 Z80 based computer (feels cheaty with that ATMEGA32A but w/e) and then maybe try actual ZX clone, even though number of parts and particularly ICs feels intimidating. Did any of you Lains did something like this? Any good tips how to easily solder buses? I plan on soldering it all on prototype board.

Greetings, you have just asked what I've been planning to do for a couple of years, the only thing turning me off was my lack of knowledge, which is no longer the case (though to be fair, I am very far from being an expert). I am at the moment learning 8bit AVR assembly, just for the fun of doing things the hard way and, in the future, build my own ATMega328p computer. Also to expand my knowledge in programming whit some actual hardware to test it. There is quite a lot of info in the net if you know how to look for it. I, for example, have a book, a rather old one, which is titled Build your own Z80 computer. I will upload it if you want it with some Z80 assembly manuals. My main goal is to do something pretty similar to this: https://www.youtube.com/watch?v=Cr7MO-5dX40 I hope you like it. I would be very nice to share some more info on the matter. Right now I am pondering whether I should buy a Rasp 3 to use its GPIO as a programmer (mainly for the AVR but also for whatever else comes).

you could also buy an FPGA and make your own hardware

>>539 I was planning to use an fpga dev board for graphics, but make the core of the system some microcontroller like atmega. Good idea or?

>>540 Sounds like an idea to start from. VGA is a pretty solid and easy standard to implement in hardware compared to creating a whole soft-core. Using some 8-bitter, you can gather a feel on the programming side, and with AVRs there's a good amount of support out there. You'd miss out tough if you're not planning on making your own processor someday. I'd suggest to read up on a HDL of your choice and testing things out in ModelSim before getting an FPGA.

I've been accumulating parts for my own Z80 build for a couple of years now. For the graphics chip, I would suggest using a VDP for one of the MSX computers (pictured). They were all Z80-based and there's *still* a large community built around them. However, it is probably a good idea to start with a UART. I've devised a simple MMU that uses a register file to extend the address space, as well circuitry to enforce different privilege levels. My plan is to write a multitasking Unix-like OS. I've also considered future expansion into a modular, multiprocessor system with shared memory and a cache on each module. As for construction, I've been breadboarding up to this point but I plan to wirewrap the final build. Wirewrapping has the connection quality and durability of protoboard or a PCB, but it is magnitudes easier to build and modify. The downside is that because there is little demand, the sockets will run you a few dollars per chip and basic tools are a couple hundred dollars. It makes buses a breeze, though.