Author Archives: aslak

More progress…. Lots of different areas

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Looking again at the VHDL for my interrupt router, I realised that adding a priority encoder was fairly simple: Instead of being the masked and active interrupt lines, ROUTED is now the number (bit position plus one) of the active line. 0 is used as a special case: no interrupt lines, which are exposed by the mask, are active. This… Read more »

Prototyping parts of an OS for MAXI09

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This past few months has been spent thinking about, and prototyping, ideas for the Operating System I want to write for the computer. But before talking about that, a summary of the other little pieces of hardware progress. Anyone who has viewed the video will be familiar with most of this.First up SPI. I have implemented a trivial SPI controller… Read more »

Physical construction of the MAXI09 PCB is now complete

Physical construction of the MAXI09 PCB is now complete. A final, 3 hour, session with the soldering iron completed that task. Here is a picture of the top of the board: I have also found a solution to the problem of unwanted flux residue. After trying out various things including isopropyl alcohol, it seems that the best approach is good old… Read more »

Sound, video, DMA; more bring up

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Construction of the MAXI09 is continuing. With each part soldered onto the board comes a limited amount of testing with the monitor. Enough to exercise the very basic level of functionality, nothing more. Proper testing, and actually making the part do cool things, will come later. The first part added was the OPL2: Since this was previously prototyped on breadboard… Read more »

MAXI09 PCB ordered and yet more prototyping

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Two more bits of prototyping work have been completed recently. The first is the keyboard controller portion. Since the MAXI09 now includes a new Amiga 600 keyboard, and because this keyboard has many more connections then the old C64 one, I have mocked up the controller on breadboard. I was able to establish the pining on the 30 way flex… Read more »

Switching to KiCAD and the MAXI09 schematic

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Pretty much since I first started using it, about two years ago now, I have been struggling to “like” gEDA. To be fair, it has many positives. The schematic capture tool is not terrible to use. It is certainly quirky. The totally non standard keyboard shortcuts being just one example of this quirkiness. But it has, in my view, significant… Read more »

MuDdy and DISCo progress, and system reset generation

I have finally solved the issue with holding multiple FPGA designs inside a single configuration flash. It seems there is a special tool just for the purpose of creating complex program files (.pof files). The details are buried in this document. So this is great news, though since I only have one PLCC84 adapter made up I won’t be able… Read more »