ROM/RAM Part 1 – addressing basics

So we are ready to start connecting ROM and RAM to the CPU, but before we do this, we will have an look at the address bus of the MC68010 Wait, there is only 23 address lines? This must mean that the CPU can only address 8 MB […]

High, low, active low and what not

When starting with logic design, there are alot of expressions that you will encounter that can be confusing. Let us start by breaking down the most common expression when it comes to computers: “it’s all ones and zeroes”. But what does it means? Well, in reality, it is […]

MC680x0 asyncronous bus

The Motorola 68010 CPU has what is called an asyncronous bus. Fancy word, but what does it mean? In simple terms there is two ways of doing things; syncronous or asyncronous. Syncronous means that all involved peaces needs to be in sync in such an way that when […]

CPU and addressing schemes

So, after putting the CPU in an breadboard, it’s time to start thinking about how memory, ROM and peripherals should be addressed. Now, there are som considerations here that makes things more or less complicated. For this, we need to understand what the CPU does when powered on. […]

First things first….an reset circuit

All CPUs needs to be powered on correctly, and m68k is no different. Just supplying power is not enough, and the CPU needs some things to ensure registers are cleared, and CPU prepared to start executing. But before that, let us look at how an CPU actually do […]

What basic tools do i need?

When embarking into these kinds of projects, there is of course stuff you need. In this post I will descibe tools that I feel is really neccessary to build stuff without going insane. I will not talk about the chips themselves, but the tools around them that make […]

An Motorola 68010 project

So, I started this blog to share my homebrew computer project. Initially it was a small project just to learn some stuff, but as usual, especially as working in the IT business, the fanged, ugly head of “scope creep” turned up. This post is to summarize my project […]

Once upon a time…..

…i was a hell of an engineer. Classical words from the movie Contact. A movie I have probably watched a hundred times. Since childhood space, rockets and technology have been a passion of mine. That and fishing…. No wonder I ended up in the IT/computer business as an […]