In a long postscript to 65816: Build 4 – Adding Expanded RAM I discussed some alternatives I tried to achieve the following memory map in my ATF22V10C PLD. There’s nothing magical about this memory map, it’s just something I wanted to try, for reasons I’ll discuss in a operating system post if I ever get …
65816: Build 4 – Adding Expanded RAM
I’ve mentioned previously having trouble getting WINCUPL to create the following memory map: I figured that since I was expanding ROM, I might as well give myself a full 32k of RAM. WINCUPL didn’t like that though, giving me an error that it didn’t have enough pterms for my ROM_CS pin. I took the easy …
65816: Build 4 – Current Status – 7/15/2022
Build 4 – Current Specification As of 7/15/2022, Build 4 has tested successfully with: Both 65C02 and 65C816 up to 10 MHz where I started to get display glitches 524k memory. Current configuration: ~457k RAM ($0000-$F7FF, $20000-$7FFFF), 55 ns ~67k ROM ($F800-$1FEFF), 70 ns 256 bytes I/O ($1FF00-$1FFFF) 65C22 VIA ($1FF10, shift register dedicated to …
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65816: Build 4 – Troubleshooting 4 – Testing a Different Address Decoder
Off and on throughout my Build 4 troubleshooting journey I kept wondering if the PLD was the underlying issue. While a PLD is handy for making after the fact changes to your build’s memory map, it also has a handy feature I hadn’t thought of before. Since the PLD brings control input and output signals …
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65816: Troubleshooting 3 – Revisiting the Build 4 Layout
I left Build 4 successfully running with the 65816 and 55 ns RAM. But it failed with memory corruption when I used 12 ns RAM. The problem was that occasionally during RAM writes, some address signals would change about 2 ns before the write enable signal would rise. This would result in a write to …
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65816: Build 4 Troubleshooting 2 – Memory Corruption
I worked on the Build 4 modifications over several weeks, partly because I was just playing around with what I had on hand when I started and partly getting sidetracked looking into why things happen instead of just getting on with the build. In this post I discuss troubleshooting the memory corruption issues I found. …
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65816: Build 4 Troubleshooting 1 – It’s the PLD, or is it?
I worked on the Build 4 modifications over several weeks, partly because I was just playing around with what I had on hand when I started and partly getting sidetracked looking into why things happen instead of just getting on with the build. In this post I discuss one of those side investigations regarding the …
Continue reading “65816: Build 4 Troubleshooting 1 – It’s the PLD, or is it?”