oompa loompa
I AM THE GOVERNATOR 
"Git 'Er Dun!"
Posts: 1,301
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Post by oompa loompa on Jan 30, 2007 23:50:00 GMT -5
Finally, I removed the stock 68k from my Genesis, and hooked up a 64 pin socket to there. I connected an MC68010 (that's right, an '010, not a '000) to my Genesis  . The 68010 works surprisingly fine on the Genesis. I can't say whether this processor speeds up games such as Sonic 2, but the processor should speed them up. I also found that the motorola processors are better to overclock, and that the hitachi made ones are the worst to overclock (even the signetics version can be overclocked) I'll try to get pics up as soon as I can ! edit: btw, i also desoldered the 32k sram chips, and replaced 64k sram chips in my genesis (expanding memory from 64k -> 128l). The extra memory will only benefit me and my os though, since no game's going to recognize it and go "oooh more memory, niiice." |
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Post by jlf65 on Feb 7, 2007 22:23:58 GMT -5
You're lucky the Genesis runs in supervisor mode all the time. The move sr,dn/move dn,sr instructions were made privileged in the 68010 and newer. That was a pain on the Atari ST/TT and Amiga series computers that ran user code (and some system code) in user mode. There were patches on both computer lines that were run by the privileged instruction exception that modified the instruction to the 68010+ instruction, move ccr,dn/move dn,ccr.
The main difference from the 68000 (besides the one above) was that the 68010 added a prefetch before certain instructions. The main one that made a noticeable difference in speed had to do with the dbcc instruction. Otherwise, the chips were virtually identical in performance.
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Post by Fonzzzz on Feb 10, 2007 20:27:53 GMT -5
Wow, you upgraded the ram?
How it work? The genesis ram is at end of mapping... 0xFF8000 0xFFFFFF, where does the other 64KB appear?
Or you added special hardware?
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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 Feb 15, 2007 1:21:49 GMT -5
the main ram is mirrored like 16 times from $F00000-$FFFFFF (i think, the lower address might be higher) in memory, so i can hook up more ram - like almost to 1mbyte
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Post by fonzzzzz on Feb 15, 2007 12:35:40 GMT -5
That's absolutely great... They should have added a MEM extention slot (like N64) |
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Post by jlf65 on Feb 17, 2007 22:00:52 GMT -5
Since you put a socket in for the 68000, you might be able to make a carrier board to allow extra mem and other stuff, like an ATA port. I know the old Amigas had various things like that which plugged into the 68000 socket. I haven't looked, so I don't know if there's enough space around the 68000 in the Genesis for that.
Two plug-into-the-68k-socket devices that were most common: an ATA port, and a 68020 card. The 68020 used a clock-doubler on the 68000 clock line to run at 14MHz instead of 7. The ATA was cool as it took BARELY any more room than just the 68000 (they fit the PAL chip underneath the 68000 to save space.
In fact, I seem to remember there being plans for a 68020 that plugs into the 68000 socket on AmiNet.
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Post by GiGaBiTe on Feb 20, 2007 17:31:44 GMT -5
the main ram is mirrored like 16 times from $F00000-$FFFFFF (i think, the lower address might be higher) in memory, so i can hook up more ram - like almost to 1mbyte Try playing the first earthworm jim and using the secret menu to see if it can see the extra memory, it would be cool if it could. |
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nathanallan
PooP MonkeeH
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Post by nathanallan on Aug 11, 2008 4:37:33 GMT -5
Wow, this is an old post! Hope noone gets mad at me for resurrecting it.
Have there been any problems with replacing the stock 68K? I would like to do this just for the heck of it if not.
Nathan
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Post by GiGaBiTe on Aug 22, 2008 2:07:56 GMT -5
Wow, this is an old post! Hope noone gets mad at me for resurrecting it. Have there been any problems with replacing the stock 68K? I would like to do this just for the heck of it if not. Nathan Just make sure that the pinouts match when you replace the CPU or you could end up frying the CPU / board. |
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Post by evildragon on Nov 30, 2012 11:44:08 GMT -5
edit: btw, i also desoldered the 32k sram chips, and replaced 64k sram chips in my genesis (expanding memory from 64k -> 128l). The extra memory will only benefit me and my os though, since no game's going to recognize it and go "oooh more memory, niiice." Sorry for digging up an old thread, but I must ask. How did you obtain 64KByte SRAM chips in the DIP28 package if they don't actually exist? That's why the 32-pin package was used for those. Piggy backed RAM? Please tell. |
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. The 68010 works surprisingly fine on the Genesis. I can't say whether this processor speeds up games such as Sonic 2, but the processor should speed them up.
