Hey,
Anyone have the schematic handy to add 8k of sram to a TLROM pcb? I got a handful of extra SRAM chips and I wanna use them to make better use of my remaining TLROM boards. I know the sram can go pretty much pin for pin on the back of the PRG and still fit in the cart shell but what I'm not sure of is what the address lines are that have to be re-wired and exactly where they go on the mapper chip.
Thanks in advance,
Shawn
you'll have to bend the sram pins backwards to "mirror" the chip.
Your schematic is basically the pin out for the MMC3 on kevtris' NES cart types doc.
I have my own scratch diagrams but they are really nothing other than pinouts. That's all there really is to the schematic unless you want an illegible rat's nest.
If you're not to sure about it all I would recommend grabbing a multimeter and tracing out your own version of the two boards and be sure to use kevtris' doc as a reference. Then you'll be able to make sense of everything for yourself and actually have a chance at getting it to work.
Can you take a shot from one of your TLROMs and post it here?
FARID wrote:
Can you take a shot from one of your TLROMs and post it here?
Like I said awhile back, the only real way to do this without using a TLSROM board is to basically solder the SRAM to the bottom side of the PRG ROM chip.
You'll have to bend all the pins 'UP' vice they way they normally point 'DOWN'. You'll basically mirror the chip and then you'll be able to get all the Data bits, lower address bits, and maybe /CE to match up with the PRG ROM. It won't be every single pin especially the power pin and /WE, but you'll have most of them match up.
You'd basically create a sandwich with the PRG ROM and WRAM as bread with the board in the middle as the meat...
infiniteneslives wrote:
Like I said awhile back, the only real way to do this without using a TLSROM board is to basically solder the SRAM to the bottom side of the PRG ROM chip.
You'll have to bend all the pins 'UP' vice they way they normally point 'DOWN'. You'll basically mirror the chip and then you'll be able to get all the Data bits, lower address bits, and maybe /CE to match up with the PRG ROM. It won't be every single pin especially the power pin and /WE, but you'll have most of them match up.
You'd basically create a sandwich with the PRG ROM and WRAM as bread with the board in the middle as the meat...
Yes I do plan on going that route of putting the SRAM on the back of the board but I don't know what the extra address lines are that need to go outside of the PRG chip and where they go to the MMC3 mapper. That part is a little more advanced than my current know how.
Kevtris' nes cart types is your best resource. If you've got a copy of SMB3 or some other TSROM (I mispoke eariler) game you can always reference that.
The ALL the WRAM address and data lines connect to the same data/address line on the PRG ROM. the only things controlled by the mapper are the /CE, CE, and /WE. they go to pins 30, 41, 42 on the MMC3 if you go by the pin numbering on kevtris' doc.
As for the PRG ROM nothing should be any different. You just have to match up the old pin out to your new ROM.
infiniteneslives wrote:
Kevtris' nes cart types is your best resource. If you've got a copy of SMB3 or some other TSROM (I mispoke eariler) game you can always reference that.
The ALL the WRAM address and data lines connect to the same data/address line on the PRG ROM. the only things controlled by the mapper are the /CE, CE, and /WE. they go to pins 30, 41, 42 on the MMC3 if you go by the pin numbering on kevtris' doc.
As for the PRG ROM nothing should be any different. You just have to match up the old pin out to your new ROM.
awesome thanks! thats exactly what I needed to know!! I'll post some pics when I get one made up.
yeah just make sure you don't get confused on the pin numbering. The first pin is to the left of the '1' on the PCB and goes counter clockwise from there with the last pin 44 being below the '1'.
It's not like you might think with the little dot being pin 1, that dot (the smaller one) is actually between pins 33 and 34.
infiniteneslives wrote:
yeah just make sure you don't get confused on the pin numbering. The first pin is to the left of the '1' on the PCB and goes counter clockwise from there with the last pin 44 being below the '1'.
It's not like you might think with the little dot being pin 1, that dot (the smaller one) is actually between pins 33 and 34.
On this linked diagram of a 6264 the pin marked as RW (read\write) is actually WE (write enable) correct?
http://upload.wikimedia.org/wikipedia/c ... ut.svg.png
Also this below pic of the MMC3 is properly labeled in regards to the pinout being used in this instance correct?
Thanks!
Yeah R/W is /WE basically it should be high for read and low for write hence R (/W).
And yes you've got the right pin numbering there.