oompa loompa
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Post by oompa loompa on Jan 9, 2011 0:59:29 GMT -5
o.o I think we'll keep LAKABAJO the way it is for now . No need to really complicate it with different kinds of funny flash carts. The LAKABAJO is the transfer suite. Uhm.... you could probably mod your Genesis and upgrade the RAM to fit bigger games, but that's all I can see coming out of LAKABAJO. There's only a total of 64kbytes of RAM, and the RAM has to occupy both the program and variables. You can run all of the stock example code , but I don't know if your Crazy Bus will fit even with VRAM initializers There's no way to swap in a new cartridge when the Genesis is powered on and executing code because of unpredictable behavior that might happen to the data bus edit: I also noticed that I forgot to include a diode part in the schematic for LAKABAJO . The diode was necessary for sending information from the Genesis to PC when the user's program was downloaded into RAM. It won't affect anything really, and loading programs will still work, it's just that it hinders a feature . We'll just not worry about it for now , until the next LAKABAJO and BEX release
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Post by Tom Maneiro on Jan 9, 2011 3:15:48 GMT -5
Wait - what!? Do i need to buy salvage a diode too? (I've noticed the sucker in the sample board pic on the main page, but since everybody seems to be doin' well without that boring diode...) Bah, whatever CrazyBus ROM weighs around a massive 800K, so a "lite" version for LAKABAJO is out of question (maybe? Only time will tell)... And i suppose that cart hotswapping is a no-go too... not at least without more invasive hardware mods. Ah well... We need no stinkin' features!
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oompa loompa
I AM THE GOVERNATOR
"Git 'Er Dun!"
Posts: 1,301
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Post by oompa loompa on Jan 9, 2011 3:54:43 GMT -5
Well the main feature here is exploiting Sonic to upload external code . LAKABAJO's been out for a year, and it's pretty stable , and there are actually many success stories from others that have gotten it working ROM dumping is pretty boring. I dunno about flash carts because most flash carts will have their own bootloader. If you still want to program your junky AM29F010 BIOS flash chips, you better get yourself the datasheet and start learning to program the PC parallel port
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Post by Tom Maneiro on Jan 9, 2011 18:15:54 GMT -5
My junk ICs are not AMD, but Intel and Macronix Anyway, here is my preliminary board design, using my null EE skills and Inkscape (SVG FTW! Also it will be on some cheap Veroboard or whatever it's spelled, since i can't and won't etch a kustom board): (Hopefully the final version will look less messy or something ) The pin header pinouts are for the standard port expansion brackets for old AT boards. My questions: - Is that the proper way to wire the 0.1uf capacitors?
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oompa loompa
I AM THE GOVERNATOR
"Git 'Er Dun!"
Posts: 1,301
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Post by oompa loompa on Jan 10, 2011 1:42:51 GMT -5
For these decoupling capacitors, place them close to the IC as possible. Also, make the wires to VCC and GND on the IC as short as possible to the capacitor I dunno, is this the first time you soldered ? Better buy some extra parts and dip sockets
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Post by Tom Maneiro on Jan 10, 2011 2:25:48 GMT -5
First time soldering? Hell no. Firs time doing a board? Hell YEAH! (those BCD counters on Digital Circuit classes don't count ) Fortunately budget is not a concern (for this time), so i will buy 3x of everything
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Post by Mairtrus on Jan 10, 2011 12:56:05 GMT -5
I suck at soldering too, but make a PCB isn't so difficult as it seems: I fried all only 2 times before get it(and only because I got help ) but using DIP sockets is a very good idea (I also put these). About the ROM dumping and the hotswapping... You can actually hotswap carts, thanks to the GG. Just be sure you aren't actually accesing to the ROM's space, turn off the GG, and change the cart, since the GG seems to tie the /CART signal by default. I created a small program for dumping cartridges using only the LAKABAJO cable and a small VB6 program (yeah, Visual Basic 6, as you readed), sending bit per bit (slooooooow), but the info starts to come corrupted after a few bytes :S ... @devster: I'm curious, where should be located the diode, and what actually prevents(or enhaces)?
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oompa loompa
I AM THE GOVERNATOR
"Git 'Er Dun!"
Posts: 1,301
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Post by oompa loompa on Jan 10, 2011 13:41:03 GMT -5
Oh, the hot-swap really works ? I'm skeptical about that at first because the data bus is not buffered from the GG to the cartridge, so any assertations or glitches from the cartridge when removing and inserting another cartridge would still corrupt the bus. I never tried it, but if it works, it works . The diode hinders the capability to send data at a faster rate from the Sega to the PC. I don't remember where it's suppose to go , but it does nothing for now because I don't think I included the routines in the lastest BEX yet Tom, maybe you can prototype this thing on a breadboard first . I say that because it might be too hard for you to do rework on a pcb if you make a mistake
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Post by Tom Maneiro on Jan 10, 2011 14:32:20 GMT -5
Oh, the hot-swap really works ? I'm skeptical about that at first because the data bus is not buffered from the GG to the cartridge, so any assertations or glitches from the cartridge when removing and inserting another cartridge would still corrupt the bus. I never tried it, but if it works, it works . More reason to make a lame ROM dumper or a junky 29Fxxx flasher Since you're unplugging the cart and NOT the GG... Anyway, it sounds like a risky venture, but AFAIK, Nintendo even tried to patent cart hotswapping on the N64 or something like that. Mmmm... breadboards... These are somewhat expensive, but i may look on getting one of these too. My plan is simple: if it works, it will be done on a stripboard/veroboard/whatheverboard. This reminds me that i also need to solder the pad cable connector to my Genesis - and this gives me another neat idea: a LAKABAJO-disable switch! This way, you can keep your adapter inside, but whenever you need to use Port 2/3/whatever, simply flick a switch. Maybe it's enough to wire the a SPST switch to the adapter VCC line?
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oompa loompa
I AM THE GOVERNATOR
"Git 'Er Dun!"
Posts: 1,301
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Post by oompa loompa on Jan 10, 2011 14:55:57 GMT -5
I'm still skeptical about hot-swapping . I think it will only work if you're "lucky", and you don't lock up the Genesis Or try direct pcb first . This sounds like a good exercise to learn , and I tried to make the circuit as simple as possible. Breadboard is if you're serious about other stuff, and going to use it again in the future I don't know about switching the adapter off using an SPDT switch. You cannot just switch off VCC as well. You can try to use a 75LS257 instead of the 74LS157 because these have 3-state outputs that you can just turn off. You'll still need to disconnect the circuit from D0 and D1 on the parallel port
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oompa loompa
I AM THE GOVERNATOR
"Git 'Er Dun!"
Posts: 1,301
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Post by oompa loompa on Jan 10, 2011 20:41:56 GMT -5
edit: nevermind, I made a mistake . It can only be implemented in 19 NAND gates, so it won't fit in 4x74LS00
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Post by Tom Maneiro on Jan 10, 2011 21:05:10 GMT -5
Bah, where is my fat Tocci's Digital Circuits book? Ah, right, buried inside a ton of old magazines and dead CD drives I SUCK at flip-flops. The LS257 thing looks neat - with a TPST switch (if i can find such thing over here) would do the job. I may attempt that experiment, sounds tempting... What happens if i just kill VCC to the current adapter while attempting to use a gamepad in the same port? Bad things?
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Post by Tom Maneiro on Jan 12, 2011 20:54:16 GMT -5
I'm building mine RIGHT NOW (no pics yet - the dickheads at my host haven't renewed my domain name yet, so i have no website today ) Since you say "place the decoupling caps as close as posible to the ICs", why not just shove the cap INSIDE the sockets? EDIT: My GG finally arrived, and my board is... well, full of cables but no shorts so far Testing later...
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Post by Tom Maneiro on Jan 13, 2011 17:25:04 GMT -5
So far, not so good... Hardware test mode results: * A/B/UP don't work at all... * C/LEFT/RIGHT/START do work nicely... most of the time. * DOWN works erratically - most of the time it does nothing, but sometimes it registers like a gazillon of keystrokes on the Genesis * Good syncs are higher than bad syncs I've checked connections several times, rechecked solder joints... maybe i FUBARed my LS157 or something? It's weird that U/D don't work, since they're directly plugged to the parport lines, and i've checked continuty...
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oompa loompa
I AM THE GOVERNATOR
"Git 'Er Dun!"
Posts: 1,301
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Post by oompa loompa on Jan 13, 2011 20:57:53 GMT -5
Is this your only computer with a parallel port? If U/D don't work, then something is terribly wrong. I would say it's the ground, but I dunno
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