C64 Core

https://github.com/MiSTer-devel/Main_MiSTer/wiki

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slingshot
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Re: C64 Core

Postby slingshot » Wed Jan 09, 2019 11:24 am

yellperil wrote:
slingshot wrote:Great! I'll test it. Didn't you try just to remove "enable" from the int firing logic? That way it still would not have the interrupt delayed by 2 enable cycles, and no need to use the falling edge.


No didn’t try that, I’m not that familiar with HDLs in general so I don’t know of those types of implications. Just learning as I go. Good to know though, thanks for the knowledge sharing.


Well it's not HDL speciality. Currently the code does:

....clocks...enable(flag interrupt)-clock(flag registered)...clocks...enable(flag noticed, int fired)-clock(int registered)....clocks...enable(CPU notices the int).

You can see it's 2 cycles where enable ='1' elapsed from the int fireing to the time when the CPU noticed it. Seems from your fix, this delay is too much, so there must be no enable cycle between the interrupt flagging and when the cpu notice it. If the interrupt firing is not in the enable cycle, then

enable(flag interrupt) - clock(flag registered, flag noticed, int fired)...clocks...enable(cpu notices the int)

Using the negative edge just makes two events in one cycle, which effectively doubles the clock frequency (it's ok here, but at higher frequencies this can cause timing problems).

enable(flag interrupt) - clock(flag registered)...clocks...enable negedge(flag noticed, int fired), enable posedge(cpu notices the int)

So in theory the end of both approach is the same.

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Re: C64 Core

Postby yellperil » Wed Jan 09, 2019 12:46 pm

Yep that makes sense, thanks for elaborating.

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Re: C64 Core

Postby Sorgelig » Fri Jan 11, 2019 12:21 am

That fix with falling_edge is too hacky.

yellperil
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Re: C64 Core

Postby yellperil » Fri Jan 11, 2019 3:54 am

Sorgelig wrote:That fix with falling_edge is too hacky.


Yes I know :( but I took the time to find it and at least I tried.
Now someone else better than I can implement it properly.
That’s all that matters, isn’t it.
Last edited by yellperil on Fri Jan 11, 2019 4:39 am, edited 3 times in total.

yellperil
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Re: C64 Core

Postby yellperil » Fri Jan 11, 2019 3:56 am

Thanks for updating the core, I look forward to studying all of your latest updates.

Mic184
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Re: C64 Core

Postby Mic184 » Fri Jan 11, 2019 9:06 am

I noticed a glitchy row of pixels on the right side of the screen kinda reacting to the screen image after the last update.
It appears the C64_20180831.rbf core isn't affected from this pixel row problem.

Nevertheless thanks for updating the core.

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Re: C64 Core

Postby yellperil » Fri Jan 11, 2019 9:26 am

In the source for the 8580 sid_voice.v, if you set default to triangle in the waveform selector, then the music plays for GUTZ and Hysteria with one slightly odd voice.

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Re: C64 Core

Postby SegaMan » Sat Jan 12, 2019 3:28 pm

Mic184 wrote:I noticed a glitchy row of pixels on the right side of the screen kinda reacting to the screen image after the last update.
It appears the C64_20180831.rbf core isn't affected from this pixel row problem.

Nevertheless thanks for updating the core.


Same here.
Vertical Line on the right side of the screen.

New Scaler looks great!
Great work :cheers:

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remowilliams
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Re: C64 Core

Postby remowilliams » Sun Jan 13, 2019 9:44 pm

Just noted the extra pixels on the right hand side in the C64 core as seem to be showing in the Amiga core - posted picture in the Amiga core thread.

JimDrew
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Re: C64 Core

Postby JimDrew » Mon Jan 14, 2019 2:46 am

I just tested the latest C64 core. Although the 1541 emulation now passes all instructions, it still fails some part of every "VIAxx" test (where xx is a number). So there are still VIA issues.
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Re: C64 Core

Postby redmist » Mon Jan 14, 2019 3:36 am

Not sure if this has been asked before...Is it possible to output a synced ~50Hz via HDMI similar to the Ultimate64 board? I would like this for smooth scrolling in PAL software.

From https://ultimate64.com/Ultimate-64

"Video

What resolution does the HDMI output use?
  • The output resolution is 720 x 576 at 50 Hz (for the PAL version), also noted as 576p50. This is a standard resolution that all HDMI capable screens are supposed to support, according to the CEA-861 standard. However, to meet the exact timing of a C64, the timing parameters of this video mode are slightly modified. I have not come across screens that do not accept the generated HDMI signal."

Sorgelig
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Re: C64 Core

Postby Sorgelig » Mon Jan 14, 2019 6:15 am

redmist wrote:Not sure if this has been asked before...Is it possible to output a synced ~50Hz via HDMI similar to the Ultimate64 board? I would like this for smooth scrolling in PAL software.

Option vsync_adjust is supported long time already. Study the forum study the Wiki for more info.

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Re: C64 Core

Postby SegaMan » Mon Jan 14, 2019 9:03 am

@ redmist

vsync_adjust=1 (mister.ini) should do what you want ;)

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Re: C64 Core

Postby Flausch » Mon Jan 14, 2019 11:10 am

But there must be a difference, because my Ultimate64 works flawlessly with my display, while the MiSTer C64 core only produces an "out of sync" message since the last update when vsync is activated?


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