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So RAM has to be refreshed about once per second if I read that right? (that will vary with the RAM in a given machine) If that's true, I'm guessing you'd need to read from multiple pages per interrupt to do the refresh through software. If a page size = 64 then you must do around 10 reads per inter...

The IRQ is triggered 50 times every second on a standard UK PAL Dragon 32/64. Do you think that resetting the computer back to normal speed for 1/50th of every second would be good enough to keep the RAM refreshed? I figured 1 time every 15 seconds or something like that would work. Machines can pr...

All I know is that if you don't get the page size correct it won't refresh properly. Didn't know that! I had assumed that so long as you were reading and writing from/to RAM that it would be refreshed. If you read/write to all RAM repeatedly that should refresh it if you do it fast enough. But the ...

I'll have to take a look at that... it looks kinda long for what's needed. All I know is that if you don't get the page size correct it won't refresh properly. If you go too long between refreshes... same thing. I think the sta needs to be uncommented too. Seems to me writes recharge the DRAMs bette...

BTW, if you want to run almost continously in the poke 65497,0 double speed mode there may be a fairly simple solution. IF the TOF interrupt is still being generated then you could create an interrupt handler that counts interrupts, after a given time, drops the speed back down for 1 interrupt cycle...

A small machine program will actually never fail in double speed mode. The RAM accesses from running it causes the RAM to refresh. When you tried to return to basic, other RAM pages not accessed had become corrupted which is why it locked up. The only reason the program that does a cold start might ...

The nearest I can think of is Jon Bird's add-on soundchip schematic: SAA-1099 Schematic I think he takes the stereo output to two headphone sockets, but the cartridge port does have a line marked "Ext Sound In" which may do what it actually suggests... Potentially it could be used for any mono soun...

Did anyone introduce a Dragon interface for the General Instruments AY sound chip?

Early Color Computers had the same problem. I think an older version of the SAM was to blame but it's been a long time since I last heard about it.