FPGA preliminaries

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This last few months has been a bit “scrappy” on the projects front. I’ve not made as much progress as I’d hoped but have started down several different fronts and have done a fair amount of reading. To learn about implementing a DMA controller, I initially started working on a new 6809 computer core on breadboard. In the end I… Read more »

PCB toner transfer wrap-up, interrupts, video, and an IO board!

I haven’t written in this journal in two months now. I’ve been busy with work, looking after my son, etc. But I have, in the past few months, squeezed in the odd hour here and there on my projects. I’ve managed to get quite a lot done, and haven’t really felt like updating this blog until now. This entry may… Read more »

Circuit for a laminator controller and PCB manufacture of the same

I have, for about a month now on and off, been working on the controller board for the toner-transferring laminator. This involved buying some new tools including a drill press add-on for my Dremel multi-purpose tool, a chuck for the Dremel, and a collection of drill bits in various sizes. First of all, here is a picture of the finished… Read more »

PCB ordered, and improvements to homemade PCBs

This last month or so I have been working on two fronts: finalising the circuit for the computer, and working on my home made PCB fascilities. So, the circuit is finished. For power the board has two options: USB, like the previous design, and a Molex harddisk power connector. Because of the high current sourcing with a PC power supply… Read more »

Design for a real Single Board Computer

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Though the previous PCB design was a vaguely useable computer, it required devices attached to an expansion port to be even moderately useful. A real Single Board Computer should be useful with just the single board. Combining a serial interface with an IDE interface should make the single PCB a computer in its own right, albeit one that only has… Read more »

A dissasembler and thoughts on a new core computer

First though, the integration of the seven segment display with the 6809 circuit. This turned out to be easier then expected. I added a bus driver component which replaces the counter to drive the mux, and in turn is driven (and drives) the databus. It also uses the read/write line and chip select control lines. The code for the bus driver is… Read more »

An 8 bit counter with 7-segment display implemented on a CPLD using VHDL

It looks like my problems with the counter were down to the 555 timer.  Replacing the crufty old 555 with an Atmel ATMega8 generating the clock signal caused the counter to start working properly. Here is the ABEL code: MODULE counter // Defined inputs CLOCK                pin 1;RESET                pin 2; // Defined outputs Q3..Q0       … Read more »