Search found 284 matches

by Charles MacDonald
Tue Nov 25, 2014 2:28 am
Forum: Announcement
Topic: Don't forget what SpritesMind is
Replies: 17
Views: 7919

I agree, it's tiresome to see the same few posters who are routinely rude to people. They refuse to be civil and give the newbies a hard time excessively. To be honest, people like that can poison a small community and should not be tolerated. SMS Power has a very friendly community and I think this...
by Charles MacDonald
Thu Nov 20, 2014 2:13 am
Forum: Hardware
Topic: Current Consumption Measurements of Various Game Cartridges
Replies: 9
Views: 4652

That's interesting, I have the JP version of the game and it doesn't have a heatsink. The chip and PCB are otherwise identical TBH I never checked the chip temperature, but the cartridge wasn't noticably warm after a few hours of use. I wonder if there are two versions of the hardware and one runs h...
by Charles MacDonald
Mon Oct 20, 2014 3:04 pm
Forum: Sound
Topic: Using the CPU clock for musical timing.
Replies: 11
Views: 3665

I wonder if it would be better to have a sub-forum dedicated to music/YM2612 related issues?
by Charles MacDonald
Mon Aug 11, 2014 4:03 am
Forum: Cartridge
Topic: Files over 4MB
Replies: 10
Views: 3486

Re: Files over 4MB

Hello there, I was trying to make a 8MB or even 12MB cartridge. However, how exactly would one do this with 3x27c322 + 74LS139? I heard that $A00000-$BFFFFF are built in and can't be accessed. Is that correct? There's some issues when making cartridges larger than 4MB: 1.) 400000-7FFFFF is used by ...
by Charles MacDonald
Wed Jul 02, 2014 3:04 pm
Forum: Video Display Processor
Topic: sprite attribute table
Replies: 13
Views: 4110

I find it weird that the VDP would actually check the link value against the current sprite limit (64 or 80), internal cache might indeed be limited in size and cause potential issues when fetching above that limit but I do not see why the VDP would limit the acces to VRAM I had assumed that for sp...
by Charles MacDonald
Mon Jun 23, 2014 4:38 pm
Forum: Hardware
Topic: Check my ac adaptor
Replies: 5
Views: 3071

don't know if it worths the money, perhaps I should simply plug it on the device and check current flowing ;) If the genny doesn't even power up, trash ! Oh I thought you were testing multiple units of the exact same AC adapter. Are these all Genesis power supplies you are testing, Or something els...
by Charles MacDonald
Mon Jun 23, 2014 2:49 am
Forum: Hardware
Topic: Check my ac adaptor
Replies: 5
Views: 3071

thanks for the details... Now I have to understand how you define the power of the dummy load needed. In fine, I'll need a dummy load (high power) and a very small resistor to measure current. If you want to verify that the adapter can provide 10V at 1.2A: R = V / I = 10V / 1.2A = 8.3 ohms P = I*V ...
by Charles MacDonald
Thu Jun 19, 2014 7:14 pm
Forum: UMDK
Topic: USB MegaDrive DevKit
Replies: 28
Views: 7322

Thanks Charles. But is it really all that unprecedented? The open-source hardware movement is gathering momentum, and I can't help but think/hope that the days of "look at this cool thing I made but you can't have it cos it's mine all mine my precious etc etc" are coming to an end. :D Ah, I didn't ...
by Charles MacDonald
Wed Jun 18, 2014 7:27 pm
Forum: UMDK
Topic: USB MegaDrive DevKit
Replies: 28
Views: 7322

Re: USB MegaDrive DevKit

Incredibly cool! Thanks for sharing the entire project like this, it's sort of unprecedented. I can't wait to see what people do with it.
by Charles MacDonald
Sat Jun 14, 2014 4:07 am
Forum: Megadrive/Genesis
Topic: Castlevania Bloodlines Password Secrets Unlocked
Replies: 4
Views: 2260

This is really great work. Thanks for sharing all the details and disassemblies too.
by Charles MacDonald
Mon Mar 24, 2014 8:25 pm
Forum: Video Display Processor
Topic: Every 8 lines scrolled horizontally
Replies: 3
Views: 2049

I have found the problem: register 0x0B was set to 1. Changing it to 3 solves the problem. Nevertheless, according to Charles MacDonald's VDP document, it should if the register is set to 1. So, this seems to be a mistake in that document. There's two line scrolling modes, 1 and 3. Mode 1 re-uses t...
by Charles MacDonald
Sun Feb 23, 2014 5:08 pm
Forum: Sound
Topic: AY 3 8912/8910 to Genny ?
Replies: 3
Views: 2247

Re: AY 3 8912/8910 to Genny ?

I'd have thought it would be difficult since the YM2612 is the one FM chip that isn't AY8910/YM2149 compatible, almost all the others (YM2203, YM2610, YM2608, etc.) have AY8910/YM2149 PSG outputs. Maybe using the SSG-EG envelopes makes the FM channels sound more like AY channels, and that's the tric...
by Charles MacDonald
Sun Jan 05, 2014 3:43 pm
Forum: Video Display Processor
Topic: DMA setup performance penalty?
Replies: 8
Views: 2922

Re: DMA setup performance penalty?

How much of bandwidth would I lose if I setup multiple DMA transfers? Does the setup and stopping of the DMA transfer on the hardware side take enough time to lose a non-trivial amount of bandwidth? When I was doing some FMV tests there was no appreciable change in speed between doing one huge tran...
by Charles MacDonald
Fri Oct 18, 2013 3:57 am
Forum: Video Display Processor
Topic: VDP color $E
Replies: 3
Views: 2283

r57shell wrote:That is what I doing now :) reading sources... and making own test rom.

Very interesting moment: Is it true for backdrop color too? :)
Luckily it only affects the sprites.

So color $0E of background layers or the backdrop appear as they should in shadow/highlight mode.
by Charles MacDonald
Thu Oct 17, 2013 10:49 pm
Forum: Video Display Processor
Topic: VDP color $E
Replies: 3
Views: 2283

Re: VDP color $E

1) Is it true? 2) Where I can read mostly latest info about VDP research? forum/doc? Yes it's a side effect of how the highlight function works. Normally for sprites using palette 3, a sprite pixel value of $0E enables the highlight effect. Now for whatever reason, possibly a bug, a sprite pixel va...