New Life Games Tech Forums

New at this, but how do I identify the payout percentage on the 27512 eprom, Bally 5500, Thanks for your help.

I think if you open the door and push the test button the display will show the payout percentage.

I am not a bally guy but a 27c512 is the type of Eprom......not the chip number that relates to the game.

For instance on a IGT platform we have 2 chips. One is a reel and the other is a game chip. The combiation of these two chips define the theme.
One is a 27c256 and the other is a 27c512, (256k and 512k respecitvely).
Different reel chips have different numbers on them which would identify the theme and % payback. However all the chips are 27c256 or 27c512's.

You can subsitute a 27c512 for the 27c256 and just burn using an offset so the data is found at the right place. This allows you to buy chips in bulk and save cash rather than having to buy smaller quantities of two types.
The cost differential between the two are negligable.

As an aside note - being able to push the button and get a percentage is handy. We usually have to look up our chip number and cross reference it in a book.

You kids today with your new-fangled machines have it so easy........    :72- :72- :72- (my explantion of how to do math with a slide rule is forthcoming)  :30- :30-

That's correct. Press the test button once and let go. The higher number displayed is the percentage for max coin and the lower number is the percentage for one coin.

ohhhhhh I didn't know the lower number was for one coin .... see you learn something new every day.

Today I learned that and 4 hours of watching cisco tech support work on my router  :25- :25- :25- :25-

Jay, the slide rule I know how to use but seriously, The offset thing has me and others confused, are you using 256's as 64's for the reel chip? ,I know why people do the offset, I don't as I would get a callback saying you burnt it on the wrong chip, but for an average person I am confused, but then again I am not average nor normal

To use a 512 where you would use a 256 you use an offset of c000 when burning.

I am not much of a hardware tech but the explanation given to me is that when you write you start at addresss 0000 at the bottom of the chip and write upwards.
However when a chip is read,  it is addressed downward.......

Subsequently when you use a 512k chip where a 256k chip is expected,  the imbeded data needs to be higher up, thus the use of the offset when burning.

Its been a while since I read any of the S+ chips so I am just going from memory but if they are 64's ...... (and not 256's) then you would probably use a larger offset if you were to use a 512k chip.

 :99-  Jay, what you're saying makes sense, but the only chips I've had experience with are the S+ chips, which are the 27c64 and 27c512, and when I use a 27c512 for a reel chip I use offest c000, as Rick originally instructed.

So I have to ask, is c000 the right offest for a 27c256 file burned onto a 27c512? :103- :103-

I know that I'm not confused about the 64 and the 512 because they are the only chips I've used so far.


<ADD> It's occurred to me that the S+ might be a special situation. As I understand it, the S+ had a limited amount of address space and the reel chip addreses had to be squeezed into a space that didn't conflict with the addresses used by the game chip and the rest of the system. Maybe that's why the S+ 64/512 offest is the same as a normal 256/512 offset. :103-

Hmmm.... working this backwards

A 27c64 is 64 kbits (not bytes) so to work in bytes we must divide by 8bits ... and the results is an 8K chip
subsequently the memory addresses would be 0000 - 1FFF
A 27c128 would be 16k bytes 0000 - 3FFF
A 27c256 would be 32k byites 0000 - 7FFF
A 27c512 would be 64k bytes 0000 - FFFF

You should be able to take the top memory range of the 27c256 of 7FFF and subtract the top memory range of the 27c64 1FFF .... which equals 6000h which should be the offset.....
However  that doesn't quite jive with with what we know.

FFFF - 3FFF = C000 ..... BUT WE ARE NOT SUBSTITUTING 512s for 128s ......  :8-

OK someone now needs to straighten this out.