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PostPosted: Mon Mar 11, 2013 9:20 pm 
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Joined: Sun Apr 13, 2008 11:12 am
Posts: 6294
Location: Seattle
Say, for the moment, you had an 8megabyte 'PROM. There would be 23 address lines, 1 control line, and 8 data lines, so you'd need two of these level shifters.
Do something like this:
Chip 1:
1DIR-5V
1/OE-gnd
1B1…1B8-SNES A0…A7
1A1…1A8-'PROM A0…A7
2DIR-5V
2/OE-gnd
2B1…2B8-SNES A8…A15
2A1…2A8-'PROM A8…A15 (unless you need to skip A15 'cuz it's LoROM)
Chip 2:
1DIR-5V
1/OE-gnd
1B1…1B7-SNES A16…A22
1B8-SNES /OE
1A1…1A7-'PROM A16…A22
1A8-'PROM /OE
2DIR-gnd
2/OE-SNES /OE

2B1…2B8-SNES D0…D7
2A1…2A8-'PROM D0…D7

I just realized that I don't know if you have a single output enable from the SNES or MAD or 74'138, or if you need to combine /RD with /CART... If the last, you'll need to make one, using a 741G32 or a two-transistor OR gate or something.


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PostPosted: Tue Mar 12, 2013 9:50 am 
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Joined: Wed Dec 06, 2006 8:18 pm
Posts: 2801
You'd need two of those because the data lines and address lines need level shifting. And any other lines that need to connect to the chip like /CE or /OE.


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