Offsets when burning different EPROMS

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Offsets when burning different EPROMS

Postby tris909 » Thu Dec 12, 2013 8:19 pm

hi there, I have done a bit of a search through the forums and haven't really found a one stop thread to answer my question with offsets writing to EPROMS. Would like to know what offsets you setup on the EPROM burner when writing to different sizes such as 27C128, 27C256, 27C512 using 12P and also what offsets for the likes of a later ECU EPROM such as vs to vy?
thanks guys.

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Re: Offsets when burning different EPROMS

Postby Holden202T » Thu Dec 12, 2013 9:21 pm

with my old willem using offsets used to work ok, but with the GQ-4X it doesn't seem to like it so I find the easiest way to do it is to stack the bin in tunerpro to suit the memcal and then burn with zero offset.

you'll need at least a 27c256 for 12P anything less is too small, and with that it will be zero offset anyways .... 512 memcal and double stack the bin file and your right. 1mb memcal (ie. nvram or 29c010) 4 x stack will work fine.

the way to work out what bin works on what chip is easy, multiply the bin file size by 8

e.g.
12P = 32kb * 8 = 256
11P = 64kb * 8 = 512

etc etc

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Re: Offsets when burning different EPROMS

Postby tris909 » Thu Dec 12, 2013 10:11 pm

Ok great I'm also using a GQ-4X that's exactly what I was looking for thankyou. Can you please explain what the stacking process means? Thankyou.

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Re: Offsets when burning different EPROMS

Postby Holden202T » Fri Dec 13, 2013 6:08 am

tunerpro has an option in the tools menu "bin stacker/splitter"

so the below screen shot shows the chip size as 128kb which is what you'd use to program an NVRAM, then the bin and block size are the same as the size of the bin file your using (your $12P tune).

stacking bins.jpg
stacking bins.jpg (68.92 KiB) Viewed 5917 times

all you have to do then is select the file 4 times in the fields at the bottom and then select an output file name and it will do the rest for you.

it basically means your tune is put on the nvram 4 times so no matter which offset the tune runs from it will be the same ... in the case of the VL400 NVRAM you can flip a jumper on the board and switch to another portion of the NVRAM and run one of these other tunes, effectively giving you another option for safety etc.

if your doing it on a VR Auto memcal for example, you have a 64kb memcal and 12P is 32kb, so you would stack it twice, this wont give you any option to switch tunes but it will populate the memcal with 2 x the bin file and one of the two will be in the right offset for the 808 to run it properly and the other will simply be there to fill up space :)

also you can split tunes the same way .... not often needed, but if you wanted to look at a corrupt NVRAM and you knew it was 12P on it, you could extract the whole 128kb file from it then split it into 4 separate bins and compare each to see if ones corrupted etc.

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Re: Offsets when burning different EPROMS

Postby tris909 » Fri Dec 13, 2013 8:03 am

ok that makes alot more sense, so for instance on my 27c256 EPROM i would stack my bin 4 time? then load layout into my GQ-4X programme and burn away?
sorry still trying to get my head around all of this.

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Re: Offsets when burning different EPROMS

Postby Holden202T » Fri Dec 13, 2013 8:21 am

well i have no idea what size bin your working with but on that 256k eprom you'd stack a 16k bin 2 times and a 32kb bin no stacking at all, and a 64k bin is too big to fit on it!

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Re: Offsets when burning different EPROMS

Postby tris909 » Fri Dec 13, 2013 8:38 am

ok making more sense each time now, how do i find out what size the bin is? and when i go to save the stacked files it its only gives me open options, is this right?

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Re: Offsets when burning different EPROMS

Postby Holden202T » Fri Dec 13, 2013 9:14 am

view the files in windows explorer on "details" view

bin sizes.jpg
bin sizes.jpg (15.46 KiB) Viewed 5892 times

you can see the normal bin file is 32kb, and the 4 x stacked one is 128kb.

in the stacking screen above, you browse to where the file is for block 0,1,2,3 and put all the same file in them, then above that where it says output file, browse to wherever you want and then i usually select the original file name then add "-4 stack" to the end of it then click ok and it should fill in the field with that details.

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Re: Offsets when burning different EPROMS

Postby vc81 » Sat Dec 14, 2013 7:52 am

So if a 12p tune is 32kb and a 27c256 chip is the minimum size to fit it on, what does the 256 mean? I thought it must have meant 256kb? By the sounds of it the 27c256 is only actually 32kb? I understand the stacking process just don't understand working out the chip size?

Any help explaining this is appreciated.

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Re: Offsets when burning different EPROMS

Postby VL400 » Sat Dec 14, 2013 8:50 am

The chips are measured in kilo bit sizes. So a 27C256 contains 256k bits or 256,000 bits of memory.

Windows is showing the bin size in kilo bytes, so 12P contains 32k bytes or 32,000 bytes.

1 byte = 8 bits, so in the case here: 256k bits / 8 = 32k bytes

32kB - the upper case B is bytes
256kb - the lower case b is bits


Edit: Holden202T has also mentioned this in post #2 of this thread.

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