First cuts from the MPCNC

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Working on the MPCNC has been a bit of a background project. It’s hard to believe I started printing the parts for it about four months ago. Here is a little about the MPCNC for some context. The project is the brainchild of “Ryan” at v1engineering.com. It  is a set of 3D printable part designs, given away freely, and other… Read more »

68000 SBC bring up

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Five MINI000 boards arrived just after Christmas. Annoyingly I got stung for the import duty, but fair enough. They were still very cheap! The quality looks fantastic, though its hard to tell from a camera-phone shot: The following was done over the course of a few weeks. Unlike the MAXI09 board bringup, I took my time and found I enjoyed… Read more »

Designing a 68000 SBC

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I have decided to be a little brave and have opted to build a 68000 SBC instead of one based off a 68008. Specification wise it is similar to the 68020 design: 68000 clocked at 16MHz 1MB static RAM (2 x AS6C4008 (PDF)) 64KB EEPROM (2 x AT28C256 (PDF)) DUART (XR88C681 or, in its place, a SC2681 (PDF))) Expansion connector… Read more »

Being sensible: a 68008 computer on breadboard

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After writing about building a 68020 computer I feel slightly silly for going back on my word: I have built up a 68008-based computer on breadboard. For one thing going right to a 68020 felt a bit like I’d be missing out; the pleasure is in exploring not the end result. I’d have left out on the other MPUs in… Read more »

Design of a 68020-based SBC

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My interest in the 68000 family of MPUs stems from two things: it’s use in my all time favourite computer, the Amiga. And the fact that it’s generally considered a very clean design compared to its then main competition. Not that this is a high bar; anything prior to the 386 is dreadful and the later CPUs are not much… Read more »

Keyboard debouncing and designing a case

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One critical issue arises when attaching mechanical switches, as found in computer keyboards, to digital electronics: switch bounce. When switches are opened and closed, the connection across the switch contacts does not cleanly transition from its previous state to its new state. Instead the switch contacts will (literally) bounce between the old state and new state before finally, after a… Read more »

Switching to WordPress

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This is completely “off topic” but worthy of a post. You may have noticed that this blog has been moved off Google’s blogspot platform onto a blog running in WordPress. I’ve never been particularly happy with blogspot. It largely works, but… The big problem (by far) is the post editing control is just awful. Unspeakable bad, in fact. And I… Read more »

An analogue joystick and implementing an SPI controller

It’s been a while since my last post. The main reason being a house move. On the plus side this is good for my projects as I now have lots more room to work on them. On the negative side, at least as far as my hobbies are concerned I’ve, somewhat unexpectedly, found myself doing some work for my old company…. Read more »

Exploring C compilers for the 6809

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Ever since I fired up my first 6809-based computer, I have wondered about the possibility of running programs written in something other then assembly language on it. Not that I don’t love writing code in assembly. But for interests sake, and because it could be a different kind of fun, I’ve been curious about running code written in higher level… Read more »