Search found 37 matches

by Haruka
Fri Jul 26, 2019 12:25 am
Forum: NES Hardware and Flash Equipment
Topic: VRC-VI multicart
Replies: 39
Views: 23110

Re: VRC-VI multicart

This is what the 74LS32 is doing on that cart (might not be wired physically like this on my cart as I just drew this from my head). The circuit below is meant to make up to the fact that 62256s have no non-inverted Chip Enable pin. VRC6_32KWRAM.PNG The second OR gate is useless, isn't it? Connect ...
by Haruka
Thu Jul 25, 2019 11:55 pm
Forum: NES Hardware and Flash Equipment
Topic: VRC-VI multicart
Replies: 39
Views: 23110

Re: VRC-VI multicart

I bought some chips and made a test.
I used a 74'139 to decode WRAM access, completely bypassed WRAM /CE pin on VRC6. The result is still a failure. It proves that the VRC6 itself is not damaged. There must be somewhere other than VRC6 that caused the weird problem.
by Haruka
Sun Jul 21, 2019 2:14 pm
Forum: NES Hardware and Flash Equipment
Topic: VRC-VI multicart
Replies: 39
Views: 23110

Re: VRC-VI multicart

What you do with the /WE signal of the FRAM? connect straight to R/W? Connected like this, right? CE# = /WRAM_CE coming from mapper logic. OE# = GND? WE# = R/W? Well, yes. To make things clear, let me explain more. Actually I made a little adapter from the circuit I posted previously. 28.png As you...
by Haruka
Sun Jul 21, 2019 7:58 am
Forum: NES Hardware and Flash Equipment
Topic: VRC-VI multicart
Replies: 39
Views: 23110

Re: VRC-VI multicart

I also noticed the difference between SRAM and FRAM. So I searched the net and found the following circuit. 27.png This circuit has been tested on my namco163 flashcart and worked fine. But on VRC6, something weird happens. If the game(bootloader for the VRC6 multicart) never enables WRAM (i.e. $B00...
by Haruka
Sun Jul 21, 2019 5:58 am
Forum: NES Hardware and Flash Equipment
Topic: VRC-VI multicart
Replies: 39
Views: 23110

Re: VRC-VI multicart

Now I understand how to use 74'32. Why not power 74'32 with +5V, and pull 62256's /CE to +3V of battery through a big res(e.g. 100k)? This eliminates the power consumption of 74'32 when cart is not working.
by Haruka
Sat Jul 20, 2019 8:24 pm
Forum: NES Hardware and Flash Equipment
Topic: VRC-VI multicart
Replies: 39
Views: 23110

Re: VRC-VI multicart

No, that won't be a bus conflict. The VRC6 itself is only going to assert /PRGRAMCE or /PRGROMCE, never both. What if the 82p cap was short-circuit? That would explain why disabling FRAM does make the game booting fine while otherwise don't. I don't suppose you have access to an oscilloscope? Nope....
by Haruka
Sat Jul 20, 2019 2:45 pm
Forum: NES Hardware and Flash Equipment
Topic: VRC-VI multicart
Replies: 39
Views: 23110

Re: VRC-VI multicart

A design flaw in the NES/FC makes it impossible to tell whether the CPU is accessing $E000 or $6000 until it's too late, so memory access to $E000 will briefly look like access to $6000. By delaying the RAM's enable signal, that momentary incorrect pulse won't be received by the RAM, and writes to ...
by Haruka
Sat Jul 20, 2019 9:57 am
Forum: NES Hardware and Flash Equipment
Topic: VRC-VI multicart
Replies: 39
Views: 23110

Re: VRC-VI multicart

Sorry for necro-posting this thread. I'm also trying to make VRC6 multicart. I'm a little confused about the replacement of 32K SRAM since it has no +CE but only a single /CE. How did you use a 74LS32 to create a +CE from other pins? Could you please share your schematic? And there is another questi...
by Haruka
Fri Jul 19, 2019 1:08 am
Forum: Newbie Help Center
Topic: Help with Nametable mirroring of Namco 163
Replies: 4
Views: 2879

Re: Help with Nametable mirroring of Namco 163

So that's the emulator's fault, not mine, right? Phew, that's a relief.
Thank you very much for your help!
by Haruka
Thu Jul 18, 2019 10:15 pm
Forum: Newbie Help Center
Topic: Help with Nametable mirroring of Namco 163
Replies: 4
Views: 2879

Re: Help with Nametable mirroring of Namco 163

Thank you very much lidnariq! I tried your solution. First I added lda #$00 sta $4800 near RST handler, forcing the game write to internal RAM once, making emulator believe this is N163. And then I modified ... ora #$C0 sta $E000 to ... ora #$40 sta $E000 so that E000.7 won't be set, preventing emul...
by Haruka
Thu Jul 18, 2019 7:09 pm
Forum: Newbie Help Center
Topic: Help with Nametable mirroring of Namco 163
Replies: 4
Views: 2879

Help with Nametable mirroring of Namco 163

Hello guys! I'm currently studying Namco 163 for a mapper hack project. But now I'm stucked on the Nametable mirroring. Unlike VRC4/MMC3/Sunsoft5/Bandai FCG and other mappers, which write some value to some specific register to set mirroring, N163 has no such registers. From what I've learned, it se...
by Haruka
Thu Jul 18, 2019 3:28 am
Forum: NES Hardware and Flash Equipment
Topic: Connect AY-3-8910 sound chip to FME-7 board
Replies: 126
Views: 76157

Re: Connect AY-3-8910 sound chip to FME-7 board

krzysiobal wrote:Yep, and 8910.A8=VCC, 8910./A9=GND, 8910.CLK=M2 divided by 2
Thank you krzysiobal! I'll try making my reproduction.
by Haruka
Thu Jul 18, 2019 2:07 am
Forum: NES Hardware and Flash Equipment
Topic: Connect AY-3-8910 sound chip to FME-7 board
Replies: 126
Views: 76157

Re: Connect AY-3-8910 sound chip to FME-7 board

It is CPU, not PRG, as you correctly think. So this is the "not so confusing" circuit, right? 74'139 -----v----- GND-|/1E VCC|-+5V 139./2Y1-|1A /2E|-CPU /ROMSEL 139./2Y1-|1B 2A|-CPU A14 -|/1Y0 2B|-CPU R/W -|/1Y1 /2Y0|- -|/1Y2 /2Y1|-139.1A AY.BDIR-|/1Y3 /2Y2|- GND-|GND /2Y3|- ----------- AY-3-8910 -...
by Haruka
Thu Jul 18, 2019 12:37 am
Forum: NES Hardware and Flash Equipment
Topic: Connect AY-3-8910 sound chip to FME-7 board
Replies: 126
Views: 76157

Re: Connect AY-3-8910 sound chip to FME-7 board

I have a question about the circuit. Why connect PRG A14 and PRG A13 to 74'139 and AY-3-8910, rather than CPU A14 and CPU A13 ? We are trying to decode CPU memory region $C000~$FFFF, not PRG, aren't we? Connecting PRG /CE rather than CPU /ROMSEL to 74'139 is also confusing me. I found that what we a...
by Haruka
Wed May 22, 2019 9:07 pm
Forum: NES Hardware and Flash Equipment
Topic: CoolBaby X7 Pocket Famicom teardown
Replies: 4
Views: 13430

Re: CoolBaby X7 Pocket Famicom teardown

1. Those two 16850 rechargeable batteries that power up everything are connected in parallel. No idea if this is good for their life-time or charging 18650. 3. Audio voltage drop and mixing resistors have non-standard values https://obrazki.elektroda.pl/6295830400_1558309850.png I think this is on ...