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Post by GiGaBiTe on Dec 5, 2004 2:40:31 GMT -5
would there be a way to jerry-rig a faster cpu and more ram into a genesis?
i have an XC68030RC25B in a box (25 MHz) and i wanted to see if i could do something with it.
it would probably require changing out the clock cystal and a bunch of other stuff (and the invention of a basterdized socket for it) its in PGA form.
also the ram on the board i looked up, its some wierd 32k chip that isnt made anymore and there are 2 of them so 64k of ram, wonder if could fit 128k or 256k
the sega board i have was made in 1990 its the first model of the genesis. i riped it out of the console awhile ago because the case was damaged and wouldnt allow the cart to fit correctly. but the board still works (the power transistors need heatsinks or they overheat within seconds of it being turned on.)
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oompa loompa
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Post by oompa loompa on Dec 6, 2004 16:12:39 GMT -5
you could replace the 68000 cpu with another 68k processor, as long as its not a 68040 or 68060 since these ones demand a 32 bit bus only. The 68010, 68020, and 68030 would work, but you'll need to jump some control lines to tell the cpu how wide the data transfer is.
but, if you do replace the processor with anything other than a 68000, most of the games by sega that depend on the execution timing won't work. 68010 and above have faster instruction execution times.
About the RAM expansion, i was thinking about doing this to my sega genesis too. The games made by sega don't see this extra ram, so it'd be useless for that. i'd add more ram if i were making my own games or programs for the genesis. you also have a size limit of 128k if you don't want the ram banked since anything below 0xFE0000 is already used. The 32k ram chips are still made today too, you can maybe find some very fast ones on newer 486 motherboards for its cache
i wouldnt touch those regulators sega stuck on the genesis too =D
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Post by GiGaBiTe on Dec 8, 2004 2:47:25 GMT -5
make an adjustable clock for the 68030?
and about those power regulators, i took the heatinks off of them and lost them ;X was going to take everything off the board and clean it since it was full of gunk.
i know of only one game that can tell the ram charge of the sega genesis while the game is loaded.
earthworm jim
if you go into the cheat menu it tell the specs on a bunch of stuff.
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oompa loompa
I AM THE GOVERNATOR
"Git 'Er Dun!"
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Post by oompa loompa on Dec 8, 2004 23:29:36 GMT -5
oh yeah, i remember robet tiny's (cant remember the name) debug thinger whenever i wanted to cheat =D. the numbers and sizes are only valid for that game, and the original hardware it was meant to run on. if you crank up the ram, the game has no clue you increased it. even if you move the ram to somewhere very close to its work ram, it will never recognize it, unless it does some kind of ram check, and checks all the 68000 locations for external implemented ram, and then actually uses it. but no game does this =P
the heatsink on the genesis 1 was too huge =o, i tossed it =D. how could you lose something that big? .........hahaha joke. i replaced the heatsink with two little ones for the to-220 package. once, i've kept my genesis running for three days straight, and these heatsinks didn't let me down =)
for changing the 68000 cpu with another variant, yes you can adjust the speed of the clock. you may have to adjust it even below the genesis stock speed though for some wierd games to work
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Post by GiGaBiTe on Dec 9, 2004 16:05:14 GMT -5
well since the sh2's on the 32x needed to be oc'd x2 for the cpus not to screw up from some wierd bus multiplier, it will probably be the same for the 68030.
7.61 MHz x2 = 15.22 MHz
or
x3 = 22.83 MHz
still within its limits, but not running at full speed.
the only game i can think might not play uber fast and actually run right is sonic 2. i bumped up the speed of the 68k to 15.94 MHz and it ran normally.
especially the bug on death egg zone where you can fight the boss more than once, or have 2 bosses at the same time. it really starts to slow down.
another game it might help is super hang on, but if you run it too fast the screen graphics will go corrupt.
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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 Dec 11, 2004 11:31:16 GMT -5
which version of the genesis do you have?
when i overclock mine above 12.0 mhz, the z80 doesn't really "setup" right so no sound is played
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Post by GiGaBiTe on Dec 13, 2004 22:06:22 GMT -5
i have 2 versons of the sega genesis, the MK-1601 and MK-1602. i use the 1601 for all of my testing (it was 10 bucks at flea market) its also the one that i only have the motherboard (no case) the MK-1602 on the other hand, i leave it bound to my model 2 Sega CD, i dont fiddle with it because it has sentemental value to me (its over 15 years old, and i have had it for that long ) suprisingly the Sega CD and the 1602 still work perfectly. and i still have the original controllers for it. i also have some very rare 6 button auto fire controllers for it that only a few games i have support them.
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Post by GiGaBiTe on Dec 13, 2004 22:12:18 GMT -5
try 15.31 MHz (double the normal speed, didnt try it yet but i will soon)
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