old genesis dev environments

Jorge Nuno · Post by **Jorge Nuno** » Fri Jul 06, 2007 10:39 pm

WOW nice ceramic cpu, there are almost no cpus like that and ones with gold pins and such...
I think 68010 is ever more dificult to find

I replaced my Z80 to a STclone (draws less current), put a PSU so i can get rid of the wall transformer,a pair of 128K*8 SRAM...
well enough of talking about my MD... heres a picture instead:

overclock is at the back of the board

tell me what you think

evildragon · Post by **evildragon** » Fri Jul 06, 2007 11:23 pm

Jorge Nuno wrote:WOW nice ceramic cpu, there are almost no cpus like that and ones with gold pins and such...
I think 68010 is ever more dificult to find

I replaced my Z80 to a STclone (draws less current), put a PSU so i can get rid of the wall transformer,a pair of 128K*8 SRAM...
well enough of talking about my MD... heres a picture instead:

ftp://jorgearmy.homeip.net/imag0014.jpg

overclock is at the back of the board

tell me what you think

you upgraded the RAM? how does that work? does it affect any games, specifically 32X and Sega CD?

Jorge Nuno · Post by **Jorge Nuno** » Fri Jul 06, 2007 11:31 pm

evildragon wrote: you upgraded the RAM? how does that work? does it affect any games, specifically 32X and Sega CD?

Well I can't test 32X and segaCD, because i don't have them

,
Right now A16 and A17 are currently tied to VCC and as expected with 64k everygame works fine

I will connect them to the 68k addresses next monday, I don't have time now (exam tomorrow, saturday)

did you see the picture? it's on my ftp so i would like some feedback about the ftp LOL

evildragon · Post by **evildragon** » Fri Jul 06, 2007 11:36 pm

no, the FTP won't load...

I wonder how the memory addresses loop now... for example, a game that normally accesses a looped address, perhaps with 128K it will fail and point to the wrong location...

Jorge Nuno · Post by **Jorge Nuno** » Fri Jul 06, 2007 11:46 pm

ok thanks for the input... I'll put it in imageshack

the memory mirroring is still working because I'm wasting the higher adresses (for now)... next week I will connect the full 256Kbytes (it is 2*128K*8) full range, then I will test my game collection... it is small thou

OK my megadrive on imageshack check the post again

evildragon · Post by **evildragon** » Sat Jul 07, 2007 12:02 am

Jorge Nuno wrote:ok thanks for the input... I'll put it in imageshack

the memory mirroring is still working because I'm wasting the higher adresses (for now)... next week I will connect the full 256Kbytes (it is 2*128K*8) full range, then I will test my game collection... it is small thou

OK my megadrive on imageshack check the post again

wow, so the RAM is surface mount.. i was gonna do that memory mod, but my surface mount soldering sucks..

Jorge Nuno · Post by **Jorge Nuno** » Sat Jul 07, 2007 12:17 am

Yes they were the only ones I had... they are even different... one is a NEC uPD441000LGW-B85X (85ns) and another is Cypress CY7c109-15VC (15ns)

the NEC one is a 3.3 Volt device so I reduced the Vcc of my system to 3.7V

Well My MD has 2 voltages: 68K+VDP+ROM+RAM+Bus.master+Z80+Osc+Ports -> 3.7V

RGBencoder+YM2612+RF -> 4.2V

3.7V are created by a switching regulator and 4.2 with a linear regulator with a diode in series (these are off-board)

NEXTmod will probably be a DTACK mod to speed up ram access

I think these posts should be moved from here because it's very offtopic

Fonzie · Post by **Fonzie** » Sat Jul 07, 2007 10:08 am

I'm moderator and cannot seems to move posts... only topics...

Jorge Nuno>
Just open a thread about this in Hardware section :
http://www.spritesmind.net/_GenDev//for ... m.php?f=13
And copy/quote all the messages that interest you.

I'll delete all the posts in this topic after that.

Thx