SpritesMind.Net

Is it just the /TIME line or are other lines required too? It depends on what kind of hardware you are mapping to A10300-A130FF, but generally it can be as simple as just using /TIME for a 'strobe' that does something when you write or read from that range. For finer control you would check the add...

I plan to make cards without the ROM. Concept: RAM, CPLD and supervisor with a memory card or PC link. The procedure is the following: when powerup the supervisor fills the primary firmware into RAM and makes nMRES. At rest of time, it handles requests from M68K (memory card or PC link access). Thu...

So the only solution is to figure out what it does exactly and get a new replacement part. Good luck I wouldn't be surprised if Charles could already tell you exactly what it does. AFAIK it's primarily address decoding, byte-lane steering, chip-select generation and DRAM refresh control. I think we...

Use 74AC245, its much better than HC or HCT and little faster than ACT. You may try F, its very slightly faster than AC, but its TTL not CMOS, but MD is all CMOS so there may be problems with F, but I think they're unlikely to happen. I could swear the non-HC/EC 68000's such as those in the Genesis...

when it comes to making 32X faster you can forget it unless you swap out VRAM chips for 60ns or faster ones. The 80ns ones are at their peaks in 32X, any extra boost is likely to give graphical corruption. Wow, I'm surprised it has to be so fast -- thanks for the info!. I am using 55 ns SRAMs, but ...

The color palette is at 0xA15200 and can be written at any time, but if you write it during the active display, the CPU waits until it gets time... up to possibly one full scanline (~65 usec). I can write to $A1518A, but reading it freezes the system (I was trying to poll PEN). Reading or writing t...

I just figured you were testing using a 32X image loaded into the ram. If you were just running test code that turned on the 32X and deasserted the SH2 reset, you would DEFINITELY run into this problem. The IP block is from 0x3F0 to 0x7FF and has to match byte-for-byte or it fails. Here's the relev...

I'm using DevSter's startup code which is the 2K block where 68000 execution starts at $800. I can control the Genesis VDP like normal, but I can't display anything on the 32X layer, or get the PEN/FEN bits to be '0' to indicate I can write to the framebuffer or palette. I can write data to 780000+ ...

I was going to mention speed as I know the 32X by default uses a much faster cycle time on the rom access than the MD does. It could still be a timing issue I think you are right. I tried plugging a Game Genie between several 32X games and the system and got similar graphics corruption. The Genie p...

I wouldn't mind making and selling a few more of these once I work out what to change in the next version. Estimated price with shipping to UK? Sorry to say it's quite expensive. $57 for the PCB, $36 for the 4M RAM, $35 for the other parts for $128 total. Doing a larger run (more boards ordered at ...

No rush. Whenever is fine. The Sega CD results were quite exciting. :D I wrote a memory map viewing program that runs out of work RAM, and used the devcart to toggle the /CART pin under software control. Both the cart RAM and Sega CD RAM/ROM/registers were at the right places, with no conflicts, in...

The idea would be to boot the CD while RAM occupied $400000 to $7FFFFF so that the CD software had 4MB of ram to load into (on the MD side). Ah, I think that would definitely work without problems then. If I can find the time I'll try to confirm it. http://dump.megadrive.org/dump/md/Legende%20de%20...

Having control over the cart line should allow you to use the 4MB with CD software... the Holy Grail I've been after for years. :lol: The way it is set up the CART# pin is grounded after a power-up reset, and then you can write to a register to set it to 1 (or back to 0). The entire $400000-$7FFFFF...

You might think of adding 4MB + SRAM. That's used by S&K + Sonic 3, and Wolf32X. There may be others, but those two I know use that mapping. Oops I had a typo, 4MB ROM+SRAM is supported. :D Based on the help I got from you and others I think 32X games should work, but I can't find my video cable to...

I finally finished my Genesis devcart. Here are the specs: - 1MB Flash (for boot program) - 4MB SRAM (using eight 512x8 parts) - 32K battery backed SRAM for save games - High speed USB interface (~250k/sec via FTDI FT245 chip) - IDE connector for mass storage Some videos: http://www.youtube.com/watc...