pcmhacking.net

yep same as what i have.

i think read this might help with second.
https://pcmhacking.net/forums/viewtopi ... 140#p16366

So now to get the checksum word for the group, add the digit pairs together - but remember these are hexadecimal ((00+15+20)^FF) = CA, and has cmp of 35

I am having problems understanding how to calc this bit.

0+1+2 = 3 - 15 = 12 (C)
0+5+0 = 5 - 15 = 10 (A)

00+15+20 = 35

however if the number was 255937

2+5+3 = 10 - 15 = 5
5+9+7 = 21 - 15 = -6

25+59+37 = 121

5-6121

So what have I missed?

Where are you getting this 15 from? Why are you subtracting it from the sum of every second digit?
And i think you missed this bit:

festy wrote:but remember these are hexadecimal

255937 is the target.
First the digit-pair nibbles -
25 59 37
Next, add the complimentary checksums, 25^FF, 59^FF, 37^FF
25DA 59A6 37C8
So now to get the checksum word for the group, add the digit pairs together - but remember these are hexadecimal ((25+59+37)^FF) = 4A, and has cmp of B5.
so now we've got 4AB5 25DA 59A6 37C8

Now convert to LSB for PonyProg -
0=0,1=8,2=4,3=c,4=2,5=a,6=6,7=e,8=1,9=9,a=5,b=d,c=3,d=b,e=7,f=f
so
4AB5 = 25DA
25DA = 4AB5
59A6 = A956
37CB = CE3D


Reversed for LSB order is AD525BA4659AD3EC.

festy wrote:255937 is the target.
First the digit-pair nibbles -
25 59 37
Next, add the complimentary checksums, 25^FF, 59^FF, 37^FF
25DA 59A6 37C8
So now to get the checksum word for the group, add the digit pairs together - but remember these are hexadecimal ((25+59+37)^FF) = 4A, and has cmp of B5.
so now we've got 4AB5 25DA 59A6 37C8

Now convert to LSB for PonyProg -
0=0,1=8,2=4,3=c,4=2,5=a,6=6,7=e,8=1,9=9,a=5,b=d,c=3,d=b,e=7,f=f
so
4AB5 = 25DA
25DA = 4AB5
59A6 = A956
37CB = CE3D


Reversed for LSB order is AD525BA4659AD3EC.

Sweet, Finally I get it...

25DA 4AB5 A956 CE31

Note you have a typo in your last digit you transposed 8 to B.

Thanks, this stuff is sooo cool, love it. Almost like I am back at school, should send you an apple!.

Okay understand the calculations. now onto the hardware.

Looking at all the information here, I see that the chip 24x444 looks to be the same as the 93xxx pin for pin. Why then do we not use the zip 93x to read and write the chip if it is the same? Why are we using 24x if that refers to a different pin out?

I was sure i'd make a mistake or two typing that up, but sounds like you got the general idea
The pin config is similar to the reverse microwire 93x devices, but the programming method is very different. there's a few pins that need different signals applied, but the big hurdle is software.
You shouldn't be using a 24c interface, they're an i2c interface aren't they? The x2444 has nothing in common with these, apart from pin count

- I have built a new xp system with a clean xp install. Installed ponyprog2000 and I can now read the chips.

... Now I am having no luck writing to the chip! A question, given I have a 4 sets of hex numbers and 4 gourps, The first group looks to be different and the 3 remaining groups are all the same. Is there a trick to write to the chips, do I have to put the check digit into a different part? Is it better to load the file from .bin ? Can some one send me a valid .bin file that I can load and test to see if it writes to a chip?

Thanks again for every ones help.. Believe it or not I am having fun!

Read in your bin, leave bytes 0-7 as they are, and replace bytes 8-15, 16-23, 24-31 with your new 8 byte pattern.

Thanks festy,

I kind of thought that would be it, but it is always good to confirm.

Do you use the PonyProg2000 software? Do you know if there are any setting that need to be changed in order to write to the chip?

No, I used my own hardware and software.