Search found 1055 matches

by NewRisingSun
Sat Dec 07, 2019 9:11 am
Forum: NES Hardware and Flash Equipment
Topic: NES Maker (for VTxx machines)
Replies: 7
Views: 53

Re: NES Maker (for VTxx machines)

They should only work if you set the mapper to 296. If you set the mapper to the correct 256.15, mapper 1 and 3 should not work.
by NewRisingSun
Sat Dec 07, 2019 8:49 am
Forum: NES Hardware and Flash Equipment
Topic: NES Maker (for VTxx machines)
Replies: 7
Views: 53

Re: NES Maker (for VTxx machines)

RS-18 uses the VT369 NoaC, on which I am not emulating MMC1 and CNROM. Which games (menu #) do you think use those directly, i.e. without having been modified for mapper 4?
by NewRisingSun
Sat Dec 07, 2019 8:46 am
Forum: NES Hardware and Flash Equipment
Topic: NES Maker (for VTxx machines)
Replies: 7
Views: 53

Re: NES Maker (for VTxx machines)

The VT32 should support UNROM and a subset of UNROM-512 without the bankswitched CHR-RAM. The other known VRT models neither support the UNROM bankswitch directly nor possess CHR-RAM.
by NewRisingSun
Sat Dec 07, 2019 12:13 am
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

I have trouble understanding the code. What is "m2_count"? "m2_count -= 256" --- there are neither 256 pixels (that would be 341) nor 256 M2 cycles (that would be 113+2/3) M2 cycles per scanline? The RAMBO-1 would never issue IRQ unless I continued toggling PA12 through v-blank, note the commented o...
by NewRisingSun
Fri Dec 06, 2019 3:01 pm
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

Take one sample of Skull&Crossbones, for example: C001 @scanline =247, PPU cycle=5: 21 M2 cycles with PA12 low since PA12 was high => game wants value (C000=0) +2 C001 @scanline =18, PPU cycle=330: 3 M2 cycles with PA12 low since PA12 was high => game wants value (C000=191)+1 C001 @scanline =212, PP...
by NewRisingSun
Fri Dec 06, 2019 2:10 pm
Forum: NES Hardware and Flash Equipment
Topic: 4in1 multicart
Replies: 6
Views: 151

Re: 4in1 multicart

The game would run as oversize mapper 47, since the menu writes the outer bank both to data and address. The PCB is a compatible subset of mapper 344, which I just updated.

The missing chip seems to be to switch between 128 KiB and 256 KiB outer banks.
by NewRisingSun
Fri Dec 06, 2019 1:58 pm
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

The problem remains that exactly the reverse behavior is needed for the problematic games.
by NewRisingSun
Fri Dec 06, 2019 1:47 pm
Forum: NES Hardware and Flash Equipment
Topic: 4in1 multicart
Replies: 6
Views: 151

Re: 4in1 multicart

There is a solder pad and an unused spot for another 74 chip. What would that one do if installed?
by NewRisingSun
Fri Dec 06, 2019 1:42 pm
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

Okay, but that observation is the opposite of what we need. What we need is a replication and explanation of N+2 behavior when $C001 is written to any time except with PA12 recently having been high.
by NewRisingSun
Fri Dec 06, 2019 1:30 pm
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

"You can send the $C001 with no fewer than 4 M2 cycles with A12 = 0 preceeding it." What does that mean? A game can write to $C001 at any time it wants to. I definitely agree that the timing of the $C001 write matters to get games to "look right". In my visually hardware-accurate-seeming emulation, ...
by NewRisingSun
Fri Dec 06, 2019 12:46 pm
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

All right, so in your test environment, the difference does not appear. Now we have to find out why it does appear in a real PPU environment. Edit: I notice in scanline 261 of the NTSC timing diagram (prerender scanline), it doesn't look like it does sprite fetches in that scanline, no blue boxes. T...
by NewRisingSun
Fri Dec 06, 2019 12:27 pm
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

I have made a cheap-looking diagram to indicate my understanding of the timings. Is this correct?
by NewRisingSun
Fri Dec 06, 2019 12:03 pm
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

Not subsequent scanline, but subsequent counting sequence. Edit: Basically: Write $C000: 32 Write $C001: 00 (PA12 mode) Write $E001 (IRQ occurs after 34 detected scanlines) Write $E000 (disable and acknowledge IRQ) Write $E001 (enable IRQ again) (IRQ occurs after 33 detected scanlines) It's this dif...
by NewRisingSun
Thu Dec 05, 2019 11:24 pm
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

If it's PA12 rises or falls: Since there are eight PA12 rises per scanline, is the number of scanlines after which an IRQ is to be generated merely prescaled by eight (i.e. MC-ACC, J.Y. Company ASIC), or is the PA12 signal filtered in some way to register only once per scanline (MMC3)? I have to th...
by NewRisingSun
Thu Dec 05, 2019 2:20 pm
Forum: NES Hardware and Flash Equipment
Topic: RAMBO-1 Mapper Investigation
Replies: 40
Views: 705

Re: RAMBO-1 Mapper Investigation

16 or 17 makes no difference; in fact, I can increase it up to 22 with no adverse consequences. Starting at 23, Skull & Crossbones starts to shake. Set it to 13 or lower, and Skull & Crossbones' status bar shakes again. The "sweet spot" basically is between 14 and 22.