Author Archives: Machina

Zolatron 64 6502 homebrew computer – first boot

Okay, so the headline is overstating matters a little, but this thing is making progress. Here’s a quick series recap: I decided to brew my own 6502-based computer. Rather than start from nothing, I built a kit, with partial success. And I’ve been following along with Ben Eater’s 6502 project on YouTube. Both taught me a lot. However, even before… Read more »

Zolatron 64 6502 homebrew computer & Ben Eater’s project – changes to the ROM

In my previous post, I mentioned how, while I’m following along with Ben Eater’s 6502-based homebrew computer project, I’m also making some revisions of my own. One of these is to use my own address decoding scheme. So far, things are working okay, but that post included a note about how I’m going to have to make some changes to… Read more »

Following Ben Eater’s 6502 project – parts 5 & 6

Back in the first half of February, Ben Eater added parts 5 and 6 of his YouTube series on building a 6502-based homebrew computer. The enhancements he made gave the computer something it has been sorely lacking – memory. And the reason the computer needed memory was so it could have a stack. Up to that point, the code had… Read more »

Chatting at home with ejabberd on the Raspberry Pi

One of the problems with having just two people living in an old, rambling house is that you spend a lot of time shouting. My More Significant Other (MSO) and I work in different parts of the house – I have an office and she prefers to work on her laptop in the living room. We often need to communicate… Read more »

Zolatron 64 6502 homebrew computer – new address mapping and decoding

Although it is possibly the slowest computer development programme in history, my Zolatron 64 6502-based homebrew design has made some progress. And this is largely due to the fine folks over at the 6502.org forum. Specifically, I have made changes to how I’m mapping the 64KB address space and the decoding I’m using to do that. I’ve been following along… Read more »

Back on Twitter

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Something weird happened to my Twitter account. I have no idea what or when, but at some point – maybe as long as a year ago – it stopped working. You’d think I’d have noticed, but the honest truth is that I treated Twitter as write-only media. I used it to announce new blog posts (which WordPress handles automatically) and… Read more »

Following Ben Eater’s 6502 project – part 4

Ben Eater’s exciting 6502 project has reached the next stage – adding a display. But before I could play along, I had some remedial work to do. I’d achieved the previous stage of being able to get the LEDs to light up, but not reliably. Something was glitching and would cause the machine to go haywire. This isn’t entirely surprising… Read more »

Making ROMs for the BBC Micro

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Here’s something I’ve only just learned about the BBC Micro: you can burn ROM chips using modern EEPROMs. Who knew?* One of the strengths of the BBC Micro was the way it handled ‘language’ ROMs. The quotes are there because while many of these ROMs were, indeed, programming languages, others were applications such as word processors, spreadsheets, utilities and so… Read more »

Fun with chips #2: SN76489 sound generator IC

If there’s one sound that makes me nostalgic, it’s the brrrrr-BIP! noise of a BBC Micro being switched on. And that sound – as well as pretty much all the Beeb’s audio capabilities – can be traced to one chip – the Texas Instruments SN76489. This chip was used in a whole host of devices, including Sega consoles and arcade… Read more »

Following Ben Eater’s 6502 project – parts 1-3

No, this is not a post about stalking. I’ve been toying with a design for a simple 6502-based homebrew computer for a while now. I’ve built a kit and am in the middle of laying out the schematic for the first board for my own design. So I was thrilled when Ben Eater, one of the best educators on YouTube,… Read more »

SmartParallel: troubleshooting with logic analyser and scope

Well, it does seem that the problem I’ve been having with the SmartParallel board is indeed that horror of horrors – the intermittent fault. Or perhaps something weirder. This is some kind of quantum device – it works only when being observed. Setting up a server The SmartParallel was working perfectly for a few days. Then I didn’t use it… Read more »

SmartParallel: tracking down a problem

Hmm… maybe I spoke too soon. No sooner had I congratulated myself on a completed project than a problem raised its ugly head. And it was one that required some tracking down. And so, as this blog is my lab notebook, I thought I’d share what happened, as I always find other people’s tales of troubleshooting to be illuminating. One… Read more »

SmartParallel: mission accomplished

It’s done. For now. After weeks of dithering, I finally got around to making up one of my SmartParallel serial-to-parallel printer interface PCBs. I chose to solder the components – mostly surface mount – by hand and that went easier than I expected. The only snag was that it didn’t work. Not right away, at least. And finding out where… Read more »

Building a photo digitiser

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Regular readers will know that, in real life, I’m a photographer. And I’ve been one for a long time, which means many of my images were shot on film. They’re not going much good just sitting in filing cabinets – I need digital copies, which is where this project comes in. But first, some caution is required: if you like… Read more »

Rat B@stard mk.1 – a rodent scarer

They’re back! It could be squirrels. Maybe mice. Possibly rats. But whatever they are, the bastards are making themselves at home in the engine compartment of the car again. We had this with the Citroen C5. Twice the twitchy-nosed little feckers chewed through the cables for the top-dead-centre sensor, leaving the car in a state where it would turn over… Read more »