The 6809 machine

Posted in Electronics, Hardware on 29/11/2019 by imekon8

The first machine I had was a CompuKit UK101, a 6502 based machine. I wanted to build my own machine, and went for a 6809 based system.

I had a metal case in which I put a toroidal transformer, a rectifier and four voltage regulators: -12V, -5V, +5V and +12V.

I used double sized Euro cards and built a backplane that could support four of these cards.

THE FIRST BOARD

This consisted of the 6809 processor, 4kBytes EPROM, 4kBytes static RAM, an ACIA, a VIA chip and an AY-3-xxxx speech synthesiser chip. This was hooked up to an 8 digit 7 segment display and a keypad to enter hex values. I hand wrote the monitor software and used a friends machine to burn the EPROM.

THE SECOND BOARD

I built a 6545 video controller card with 4kBytes of dual ported static RAM. The 6809 has a symetric clock, so one half could be the video controller, the other the CPU. I initial had problems with the static RAM being too fast, as it picked up addresses that weren’t read on the video side resulting in the first character being displayed as a rapidly changing character. I solved this by shifting the clock until it loaded the address 250ns after the video bus supplied it and the issue went away.

I created my own character generator, 128 characters in the first part and blocky graphics in the second part.

THE THIRD BOARD

I designed a dynamic RAM board with 8 1 bit chips that gave me 64kBytes, and did the essential refresh in TTL counters. The 6809 had no support for dynamic RAM (unlike the Z80), so I had to design my own. It surprised me when it worked first time and was rock solid.

THE FOURTH BOARD

I got hold of data on a Western Digital chipset – two chips. I bought a double side 5ΒΌ” floppy disk drive and built the electronics around the chipset. I used hardware to drive the timing for the heads, motors etc. I eventually got it working and got 1.8MBytes out of a standard floppy and started running FLEX with it.

All these boards were wire wrapped. It did not last and the main CPU board died. By then, I’d moved on, and got interested in the BBC range of machines. I went from Acorn Electron, to BBC Master and finally the Acorn Archimes A410/1. I still have that in my garage… rotting away…

CompuKit UK101

Posted in Electronics on 26/11/2018 by imekon8

In the late 70’s I convinced my parents to buy me a CompuKit UK101 (see https://en.wikipedia.org/wiki/Compukit_UK101). The kit arrived, minus ROMs, and I put it all together, soldering the sockets, resistors, capacitors etc.

Then waited for the ROMs. Promises were made and broken, letters of complaint written and… eventually the ROMs arrived. I plugged them in, and nervously switched it on. I was greeted by the boot up page and I had my first home computer!

STEM

Posted in Uncategorized on 11/08/2018 by imekon8

I’ve heard the acronym STEM until recently…

Science, Technology, Engineering and Mathematics.

I’ve become a STEM Ambassador. I’ve talked to school kids about having a career in STEM. My first session was a careers dating event where about six kids ask questions trying to guess what I do, then I talk about what I’ve done. This goes on for about two hours and you see a lot of different groups.

The second was more of a careers fair where I represented myself as someone in a STEM career and talked about it. I got a lot of interest when they found out I’d worked in the games industry!

Future Worlds

Posted in Uncategorized on 11/08/2018 by imekon8

How could I forget this one…

FutureWorlds mentor

My first degree is from Southampton University, so I went back there to talk about some of the things I’ve done over the years.

Game Off 2017

Posted in Games, Godot, Programming on 08/11/2017 by imekon8

I’ve never done a game jam before, so this is my first!

https://itch.io/jam/game-off-2017

The theme is “throwback”.

Well, I remember a game I played a long time ago. It was like asteroids but… not like it. It had colourful explosions that filled the screen and was crazy to watch. It also had black holes.

So, I’ve decided to do something similar. I’ve called it WakiZoids. Here’s a few screenshots from the game in progress:

wakizoids1

and another…

wakizoids2

This one has the “ACME Tracking” display. A simple radar showing you objects of interest. The original asteroids had rocks and one spaceship. I’m going for loads of rocks, lots of spaceships of varying types, beasties, sentinel ships… hyperspace?

All in one month?

EEK!

 

The world is made of tiles

Posted in Uncategorized with tags on 15/09/2015 by imekon8
tiles

The World is made of Tiles

An application I put together with Delphi Seattle 10 for 64 bit Windows. Should run on MacOS etc…

The Apple tax

Posted in Uncategorized on 30/12/2014 by imekon8

Both Android and Apple charge a yearly fee to get apps onto their respective stores. There is a big difference…

To get an Android app onto my own devices for testing, no problem. I can build and APK and get it onto the phone, then install it.

To do the same on iOS… you have to pay Apple’s developer fee.

I release a free app on either platform, I pay for it.

So where’s the incentive to release a free app for either platform?

Fill the app with adverts?