Search found 37 matches

by MrD
Sat Feb 22, 2020 2:41 am
Forum: Megadrive/Genesis
Topic: Is a space character required at $104?
Replies: 6
Views: 388

Re: Is a space character required at $104?

Ah yeah most definitely. I did that for Blast Arena Advance on the GBA in the old days.
by MrD
Fri Feb 21, 2020 2:08 am
Forum: Megadrive/Genesis
Topic: Is a space character required at $104?
Replies: 6
Views: 388

Re: Is a space character required at $104?

Not required, there are some unlicensed games doing exactly what you want to do, like "WISEGAME" for "Funny World & Balloon Boy". That's great, exactly what I wanted to know, thanks :) That said I'd suggest you to try to not invent new stuff and reuse protocols of other flashcarts if you can. For S...
by MrD
Thu Feb 20, 2020 4:09 am
Forum: Megadrive/Genesis
Topic: Is a space character required at $104?
Replies: 6
Views: 388

Is a space character required at $104?

'SEGA' is required at $100-$103, but is having a space at $104 required or just convention? For my Game Raccoon cart, I was considering adding the ability to let games have Game Raccoon-specific functions (basic stuff: 'open a file gametitle_X.sav', 'read byte', 'write byte', 'close file') if they h...
by MrD
Tue Feb 18, 2020 10:28 am
Forum: Cartridge
Topic: Designing MD sdcard flashcart for fun, advice?
Replies: 24
Views: 5051

Re: Designing MD sdcard flashcart for fun, advice?

Rev 1 is at PCBWAY :)
by MrD
Fri Feb 14, 2020 10:51 pm
Forum: Cartridge
Topic: Designing MD sdcard flashcart for fun, advice?
Replies: 24
Views: 5051

Re: Designing MD sdcard flashcart for fun, advice?

https://cdn.discordapp.com/attachments/ ... cfinal.png

OK if there's no objections I'm gonna get this made as Revision 1 :D
by MrD
Fri Feb 14, 2020 4:48 am
Forum: Cartridge
Topic: Designing MD sdcard flashcart for fun, advice?
Replies: 24
Views: 5051

Re: Designing MD sdcard flashcart for fun, advice?

Here's the relevant code from entry_point.68k.asm in the GR Rev. 0 source. Nothing really special about it. :) ; The RAM-resident Game Raccoon executable image is installed ; at the front of RAM. RACCOON_RAM_RESIDENT_DESTINATION = RAM_START org $200 ; We're going to put the binaries blob at $200 so ...
by MrD
Thu Feb 13, 2020 7:33 am
Forum: Cartridge
Topic: Designing MD sdcard flashcart for fun, advice?
Replies: 24
Views: 5051

Re: Designing MD sdcard flashcart for fun, advice?

Hi Squall :) I'm not sure I understand your design. I think you should make a new thread with your schematic in it so we can follow it. I need to understand how to load and execute a block of code on the console ram, I intend to use a 74HC595 on the date bus to increase the load percentage, but as t...
by MrD
Mon Feb 10, 2020 3:55 pm
Forum: Cartridge
Topic: Designing MD sdcard flashcart for fun, advice?
Replies: 24
Views: 5051

Re: Designing MD sdcard flashcart for fun, advice?

https://www.mrdictionary.net/gameraccoon/ I've written a huge big blog about the two months it took to specify, design, manufacture and program the Game Raccoon Revision 0. :D All the technical knowhow will be old hat to you guys, I'm sure, but you might enjoy reading how I got to the current state....
by MrD
Thu Jan 30, 2020 10:29 am
Forum: Cartridge
Topic: Designing MD sdcard flashcart for fun, advice?
Replies: 24
Views: 5051

Re: Designing MD sdcard flashcart for fun, advice?

I think it would work, assuming flash is fine with its !CE always low. Logic itself should be sound, disregarding any timing issues. Alright :D awesome! Sorry for being pushy, I'm just excited to get it working. I think the Flash is okay with !CE being low - in Revision 0, a resistor pulls the Flas...
by MrD
Tue Jan 21, 2020 8:30 am
Forum: Cartridge
Topic: Designing MD sdcard flashcart for fun, advice?
Replies: 24
Views: 5051

Re: Designing MD sdcard flashcart for fun, advice?

Okay! :D I've laid out Game Raccoon Revision 1. It's basically the same, with the same three 16-bit transceivers translating signals from the Mega Drive and controlling conditional data flow to and from the 5V world to the internal address/signal/data buses. - The FLASHREADY signal is properly pulle...
by MrD
Thu Jan 16, 2020 5:55 am
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 2436

Re: Cartridge slot questions

*wonders if Tiido noticed that edit* Alright, still trying to understand what /CAS2 does no matter how many times I get it explained x_X So far all I can seem to understand for sure is that /CAS0 asserts before it and that /ASEL is somehow involved (not sure about /ASEL's timing though). Oh, and th...
by MrD
Fri Jan 10, 2020 11:48 pm
Forum: Cartridge
Topic: Designing MD sdcard flashcart for fun, advice?
Replies: 24
Views: 5051

Re: Designing MD sdcard flashcart for fun, advice?

Thanks :) The board at least looks the part, if not entirely functional. For any software that doesn't use DMA it works great, which includes my YM instrument maker. For anyone who wants to get started in 68000 programming for the Mega Drive, it's totally usable for trying out programs. (Yours for c...
by MrD
Fri Jan 10, 2020 1:33 am
Forum: Cartridge
Topic: Designing MD sdcard flashcart for fun, advice?
Replies: 24
Views: 5051

Re: Designing MD sdcard flashcart for fun, advice?

I've written a big ol' technical page about Game Raccoon Revision 0 ! Everything worked exactly as I'd hoped, in terms of !TIME, the PIC, the Flash, the SD card, etc. But as you can see my design uses !AS as a read strobe which I'd thought was alright based on the comments I'd gotten from various pl...
by MrD
Fri Jan 03, 2020 7:32 pm
Forum: Hardware
Topic: Most up to date Mega Drive cart pinout?
Replies: 6
Views: 773

Re: Most up to date Mega Drive cart pinout?

Ah, thank you! That makes more sense. I was working off a document that said /CAS0 was active in $000000-$7FFFFF (but that range is /ASEL, if I remember right). (Also confusing me is that the Sonic 3 cart uses !TIME as the clock to a D-type register for bankswitching without combining it with an out...
by MrD
Fri Jan 03, 2020 11:00 am
Forum: Hardware
Topic: Most up to date Mega Drive cart pinout?
Replies: 6
Views: 773

Re: Most up to date Mega Drive cart pinout?

Thank you both. :) There are a few things that I'm still not sure of. Are the cart port's B28 !LWr and B29 !UWr asserted for the whole address space? Does B31 !Time being asserted by itself with no write indicate !OE from the !Time address region? (in other words TIME!CE = !TIME, TIME!OE = (!Time or...