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 Post subject: EhBasic and interrupts
PostPosted: Sun May 03, 2020 5:37 pm 
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Joined: Tue Jun 19, 2018 8:28 am
Posts: 122
I have some free time, so I'd like to develop my homemade 6502 computer a little bit further.
I need to implement an interrupt support for some peripherals, mainly M6242 RTC and MC6840 timer. Then I'll probably write routines for ring buffer support for UART transmission.
This is quite easy task, I already implemented M6242 and MC6840 support in my other 8080 and 6502 designs, but then I was writing the code from scratch. Now I need to include it into existing code od EhBasic, without braking it.

So just to be sure, I'd like to ask... In min_mon.asm there is a IRQ_CODE routine. Should I write my interrupt support into it, asking my chips if they reported interrupt? What IrqBase flag byte does?


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PostPosted: Sun May 03, 2020 6:19 pm 
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Joined: Tue Mar 05, 2013 4:31 am
Posts: 1373
Take a look at this post.

viewtopic.php?f=5&t=5212

I ended up removing all of interrupt code which saved some space and yielded a bit of extra performance. I also have a CMOS version that is more easily implemented with an existing system... meaning no Min_Mon code required. All you need are the main vectors for console input and output, a contiguous section of page zero and configure the memory sections above the stack.

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Regards, KM
https://github.com/floobydust


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