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PostPosted: Fri Jun 02, 2017 3:57 am 
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How about coming up with a standard for an expansion port device?

criteria:
-needs to fit inside the expansion shell or elsewise not add to the dimensions of the unit.
-include a utility timer
-include the audio bridge
-other things while at it? i/o handling? port forward?
-maybe: open standard; anyone may reproduce it?

this way, you only need one device for several "augmented" programs, more applications are likely to use it vs. this mapper has this benefit but that mapper has that benefit.

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PostPosted: Fri Jun 02, 2017 8:23 am 
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Oziphantom wrote:
TOD - in the CIA case takes a 50 of 60hz signal ( aka 1 half of an AC line ;) ) and basically does the following
5/6 counter which then feeds a 10 counter which then feeds a 60 counter which feeds a 60 counter which feeds a 12 counter which feeds a 1bit flag.

In other words, exactly what incGameClock and update_game_time do. I'm just trying to find the most resource-efficient way to handle TOD, particularly balancing CPLD resources against CPU RAM and PRG ROM.

Oziphantom wrote:
adds code complexity

The alternative adds code complexity to the CPLD. There's no free lunch, but if you can delay it to 2 PM, there are sliders at Arby's.

And a clock for something like Animal Crossing would need to be an RTC, or at least have the accuracy of one, in order to keep the game's day/night cycle in sync with the player's. Harvest Moon with its two orders of magnitude speedup would need TOD that pauses in buildings.


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PostPosted: Fri Jun 02, 2017 10:25 am 
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Quote:
It a call to have mappers add timers as standard, to put it on the radar so to speak

Noted. The hurdles of creating the mapper definition, test rom, emulation, and software targeting said mapper are still what's keeping it from going anywhere besides on the radar. FWIW, I already have hardware/board designs that can support what you're asking for, but having the hardware on the board is the easy part. Takes effort to get over all those hurdles. I've started to make it a goal of mine to allow the hardware on my designs to be configurable by the end user. I've got a lot of work ahead before I can meet that, but the first steps have been taken. End goal is some tutorials that help devs get started with mapper development if they'd like, allowing them to bypass the board design steps.


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How about coming up with a standard for an expansion port device?

A standard is fairly worthless till someone scrounges up somewhere on the order of $10-40k for a run of connectors that fit in the exp port (assuming you're talking frontloader NES.)

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PostPosted: Fri Jun 02, 2017 11:41 am 
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Oziphantom wrote:
kind of timer I mean as they are found on pretty much every 6502 based and some non 6502 based machines. I.e 16 bit timers with one shot or continuous mode, a force latch, maskable interrupt generation,and the ability to count underflows of a paired timer to get 32bit timers. [...] The cycle counters basically can't be done at the moment to my knowledge, some have H PPU based counters, but I don't think any have cycle counters.
Just to make sure we're starting from the right page... when you say "cycle counters", do you mean the same thing that we do in this page ?


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PostPosted: Fri Jun 02, 2017 11:50 am 
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FWIW Sunsoft's FME-7 with 16bit CPU cycle counter is the most popular/available of all those choices.

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PostPosted: Sat Jun 03, 2017 12:16 am 
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When I saw them originally I saw the MMC3 references, which made me think they had some PPU based link, but ignoring it,looking at the more obscure ones they are strict CPU cycle timers/counters ;) the FDS has a timer, but others have counters, but are actually timers and some are counters ;) just rather limited ones.

Is the Namco 129 available?

Sidenote is there a reason why most put the registers under the ROM? And not below the ROM area?

I think Animal Crossing would need a RTC so it Knows it is Christmas, on Christmas to do the special event. Harvest Moon is in "fairy" time and I don't think even a pause-able TOD would be helpful ;)


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PostPosted: Sat Jun 03, 2017 12:38 am 
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Oziphantom wrote:
Sidenote is there a reason why most put the registers under the ROM? And not below the ROM area?
Two things come to mind...
1) it's ROM, so there's no reason to not have a read-only and write-only function overlap
2) the NES doesn't provide access to CPU A15, just CPUA15 NAND Φ2, so it's electrically simpler to not have to compensate for the timing difference between Φ2 and CPUA15 NAND Φ2

Oziphantom wrote:
Is the Namco 129 available?
Explicitly looking for a readable one timer? I think that's the only one.

I don't know of a reproduction for it, because the wavetable synth portion uses a enormous number of bits of state.


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PostPosted: Sat Jun 03, 2017 12:57 am 
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lidnariq wrote:
Oziphantom wrote:
Sidenote is there a reason why most put the registers under the ROM? And not below the ROM area?
Two things come to mind...
1) it's ROM, so there's no reason to not have a read-only and write-only function overlap
2) the NES doesn't provide access to CPU A15, just CPUA15 NAND Φ2, so it's electrically simpler to not have to compensate for the timing difference between Φ2 and CPUA15 NAND Φ2

well in case of 2, fair enough.....

lidnariq wrote:
Oziphantom wrote:
Is the Namco 129 available?
Explicitly looking for a readable one timer? I think that's the only one.

I don't know of a reproduction for it, because the wavetable synth portion uses a enormous number of bits of state.

Looking at the wiki the Namco 163 = 129 + sound port, so the 129 is the same as the 163 only it doesn't have the sound chip? The 163 audio is also on the 129, just the 163 has an extra 128bytes of RAM for audio
R/W + Latch is the holy trinity, but the NES seems to be a "pick 2" system ;)


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PostPosted: Sat Jun 03, 2017 8:41 am 
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The 129 is "just" a buggy version of the 163. It doesn't have a functioning wavetable synth, but is otherwise identical.


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