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Sasq
Registered: Apr 2004
Posts: 155 |
Basic emulator
How much of the C64 do you need to emulate to run (poke free) basic programs ? |
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JackAsser
Registered: Jun 2002
Posts: 1989 |
You need the cpu, rudimentary cia impl with timer and keyboard input, a hacked vic (kernel poll d012) + rom and ram correctly mapped. Did one i JavaScript to emulate putchar for a terminal program |
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Sasq
Registered: Apr 2004
Posts: 155 |
CIA is what will require some work I guess, especially keyboard.
What interrupts needs to be generated, only timer ? |
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Sasq
Registered: Apr 2004
Posts: 155 |
...and do you still have the source ? |
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chatGPZ
Registered: Dec 2001
Posts: 11108 |
you only need cia ports and irq that fires 60 times a second... all the rest you can ignore
what are you trying to do though? are you aware of MiSTs basic interpreter? |
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Sasq
Registered: Apr 2004
Posts: 155 |
I have 6502 and petscii/text mode emulation already, and mapped basic/kernal so I just wanted to to go a step further.
(as mentioned in the bass thread;)
https://youtu.be/g1uuhz7Qupw |
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JackAsser
Registered: Jun 2002
Posts: 1989 |
Quote: ...and do you still have the source ?
I’ll have a look! Send you on FB later tonight |
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tlr
Registered: Sep 2003
Posts: 1714 |
If poke-free, you only need small parts (I/O) of the kernal to run basic in emulation and those parts may be stubbed off.
I do this here: blitz 0.1
It runs a blitz compiled binary but that's more or less the same as running a basic program.
Disclaimer: I may have left out a few hooks if they weren't required for blitz. |
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Sasq
Registered: Apr 2004
Posts: 155 |
Hmm yes that seems to be more about intercepting the kernal than implementing the necessary CIA stuff.
Although I am interested in this too. |
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tlr
Registered: Sep 2003
Posts: 1714 |
Quote: Hmm yes that seems to be more about intercepting the kernal than implementing the necessary CIA stuff.
Although I am interested in this too.
The point of my example being: the basic interpreter doesn't really require any hardware, only the screen editor does and that's in the kernal. |
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Martin Piper
Registered: Nov 2007
Posts: 634 |
If you patch out some raster waits etc. You don't even need I/O or CIA. Just CPU will do |
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