ATMEGA328 GAME SYSTEM WITH 6502 EMULATOR MOD
more experimentation needed.Īlso I'm unsure about the M500/M5000 mod resistor - (4K7 or 10K in series between the 1MhzE bus clock, and the E signal on the M5000 schematic).
ATMEGA328 GAME SYSTEM WITH 6502 EMULATOR SOFTWARE
I'm not sure I've implemented the selection jumpers correctly - or I may simply have the wrong software loaded. I've built up a second board configured as an M3000 extender in order to stack on the first M5000 - but I've not yet been able to make it function. Maybe select some capacitors to roll the audio off closer to 20kHz.
![atmega328 game system with 6502 emulator atmega328 game system with 6502 emulator](https://miro.medium.com/max/1169/1*YmlIH1RPib_wlm03A97vEA.png)
I need to sit down and do the filter calculations to see if the original circuit matches this observation. Removing them leads to a more detailed sound. I found the original output filter was totally killing the frequencies above 10kHz, making it sound somewhat woolly on my monitor speakers. The heat could be an issue as I'd like to enclose a couple of the boards in a 3d printed enclosure, so if it's possible to run cooler that's a bonus. So I would expect that power consumption could be halved if all the LS ICs are replaced with HC versions. As an experiment I replaced about a dozen of the 74LS chips with 74HC equivalents I had in my parts store - and it appears to still function OK, but now draws about 300mA, and they don't get so warm.
![atmega328 game system with 6502 emulator atmega328 game system with 6502 emulator](https://user-images.githubusercontent.com/26856618/34910807-7ae880fa-f871-11e7-996c-24e31a616b10.png)
With the original spec 74LS ICs it's drawing about 400mA off the wall-wart, and the chips get quite warm. 78 regulators provide +15V/-15V for the analogue section, and a 7805 pinout compatible switching module provides 5V for the digital side. It's running on a 0.5A 15V AC-AC wall wart. I made a slight error on the power input, forgot to tie one side of the wall-wart supply to ground. The memory ICs and 6070 DAC were supplied NOS from Utsource. Looking over some of the manuals, I'm excited to have a play with the software suite and make some noise with it.
![atmega328 game system with 6502 emulator atmega328 game system with 6502 emulator](http://uzebox.org/website/images/plugged.jpg)
All the LS series logic ICs are available (I had about half in my bits box), and the 6070 DAC and memory ICs are available from UtSource for a reasonable price. The power circuit should be enough to power both PCBs in a 5000/3000 system.Īt the moment it's very much a personal project - but if it's successful it'd be nice to be able to do a PCB run for anyone interested in making one. The 5V supply for the digital side would be via a Recom switcher. The aim is to allow the same PCB to be configured with jumpers to be either a Music 5000 or 3000 board so two can be stacked for a complete system, with the possibilty of sharing the same power circuitry and stereo output.įor safety, I'll be changing the power circuit to be powered by an external 15V AC-AC adapter, with 7815/7915 voltage regulators to provide the power for the DAC and opamps. There's a way to go, but I'm more than half way laying out the tracks.