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XL/XE Checksums?


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#1 Larry OFFLINE  

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Posted Thu May 6, 2010 6:53 PM

I've been trying to learn more about the XL/XE checksums so I have several questions...

According to "Mapping the Atari (revised)" Appendix 12,

PEEK(65527) ($FFF7) is the revision number of the OS. (Mine is 2 on this particular XE)
PEEK(65528) is the LSB of the checksum. (Mine is 140)
PEEK(65529) is the MSB of the checksum. (Mine is 108)

Does anyone know of a BASIC or Action! program that calculates the checksum of the OS? Seems like this would be useful but I've never seen one.

What bytes in the OS (if any) are excluded from the checksum calculation? This would be laid out pretty clearly in a Basic prog.

Thanks,
Larry

#2 Rybags OFFLINE  

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Posted Thu May 6, 2010 7:23 PM

Info you need is http://www.atariarch.../appendix12.php

XL OS has various checksums for ROM regions $5000-$57FF, $C002-$CFFF, $D800-$DFFF and $E000-$FFF7.

The checksum is a simple 16-bit add, so is different to the way SIO does it (8-bit, adding Carry back in each time).

BASIC program would be fairly simple, something like:

1000 CHECK=0
1010 FOR A=START TO FINISH
1020 CHECK=CHECK+PEEK(A):NEXT A
1030 H=INT(CHECK/65536):CHECK=CHECK-(H*65536): REM DO AND #$FFFF on checksum

Edited by Rybags, Thu May 6, 2010 7:26 PM.


#3 rdea6 OFFLINE  

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Posted Thu May 6, 2010 11:39 PM

I got these progams from one of the forums, can't remember where..........but back when I was doing a lot of MyIDE OS Eprom burning.



Attached File  chksum&rom.zip   2.03KB   159 downloads

good luck!

#4 flashjazzcat OFFLINE  

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Posted Fri May 7, 2010 2:37 AM

Is the cartridge checksum worked out in the same way? I'm concerned as to what will happen with a bank-switched cart when reset is pressed...

#5 Rybags OFFLINE  

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Posted Fri May 7, 2010 2:56 AM

Cart checksum isn't stored anywhere in ROM... was only introduced in XL to detect if one is hotswapped.

It's only an 8-bit value, and for whatever reason calculated by adding $BFF0-CFEF, adding the carry back into the sum (except for carry from last add)

Browse the XL OS around C4C9 for the routine that does it.

#6 flashjazzcat OFFLINE  

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Posted Fri May 7, 2010 4:57 AM

Cart checksum isn't stored anywhere in ROM... was only introduced in XL to detect if one is hotswapped.

It's only an 8-bit value, and for whatever reason calculated by adding $BFF0-CFEF, adding the carry back into the sum (except for carry from last add)

Browse the XL OS around C4C9 for the routine that does it.

Thanks - I'll do that. :)

#7 Larry OFFLINE  

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Posted Fri May 7, 2010 6:20 AM

Thanks to all, and especially Roy.

Perfectly clear Basic programs -- they will go immediately into to my "A-list" utilities! :cool:

-Larry


I got these progams from one of the forums, can't remember where..........but back when I was doing a lot of MyIDE OS Eprom burning.



Attached File  chksum&rom.zip   2.03KB   159 downloads

good luck!



#8 Kyle22 ONLINE  

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Posted Mon Feb 2, 2015 9:41 PM

My Sunrise Z1000b programmer has a checksum function that works beautifully with OS ROMs.

 

Here: https://kickass.so/n...r-t7411233.html

 

is a torrent with software for it.  It is designed for a Neoware CA15 thin client connected to the Serial port of the Z1000b (or Needham's SA-20), but should be adaptable to many machines.

 

I made this, and have used it many times without a single failure.

 

Hope it helps.

 

Attached Thumbnails

  • Sunrise.jpg


#9 Kyle22 ONLINE  

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Posted Tue Feb 3, 2015 9:57 PM

Here is the README from the torrent I mentioned above. Note that you need to use a USB flash drive to install it onto your thin client, or you may extract the dd image from the zip file and copy it to your drive any way you like.

 

 

 

 

Welcome to my attempt at an easy solution for older device programmers.

Remember about limited writes to flash drives!  For that reason,
drive D: is set up as a RAMdisk, and C: is locked at boot time.

Use D: for temporary storage, then, copy your files using XTree
to/from the Network drive E:.

You WILL need to modify the startup files to make it work on your network.
The choices in the menu should do it. First, Unprotect the Flash, then
Edit AUTOEXEC.BAT and replace my network info with yours.
Do NOT change anything else, Do the same in Net connections.
Re-protect Flash, re-boot and test your work.

If you are running this on a Neoware CA15, that's it, but if you use
different hardware, then you need to select a different Net card driver,
probably need to re-optimize QEMM, etc.  It can be a very challenging
and time consuming process, and definitely beyond the scope of this readme.

To use this on a Needham's SA-10 or SA-20, Connect your Programmer to
the COM1: port and run the Needham's software from the menu.  Check your
file pointers, and MAKE SURE to include D:\EPROM\ in the PC Filename.

When saving .HEX files, it will be necessary to Edit the resulting file,
and remove the first line. In the XTree Editor, use Ctrl-Y.

Sunrise Z1000B is a little different, COM1: connected to Port A, to
send a .HEX file to the Programmer, Set up the transfer on the
Programmer, when it asks I/O port A/B, go to XTree, select your .HEX
file, press F9, then press A on the Programmer, then (quickly) select
Send Direct to COM1: in the Menu.

Use Procomm to receive .HEX files from the Programmer, pgdn key, ASCII
format, esc when done.

ALWAYS Start the Receiving end first, also, No need to edit .HEX files
as with the Needham's.

*** Important***  Remember that files go in D:\EPROM.  You *MUST* re-log
the D drive to see the new files.


Atari BASIC Ver. C is included in c:\eprom.  Use it to test.

the J key in XTree will compare two files, it is a VERY useful tool.

Good Luck!

-Kyle
 



#10 Quantum Mechanic OFFLINE  

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Posted Fri Feb 6, 2015 6:46 PM

When I was doing a lot of OS ROM tweaking/burning on my 8-bit machines, I found the easiest way to deal with the OS checksum was to just disable the checksum test in the OS code.



#11 JAC! OFFLINE  

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Posted Fri Feb 6, 2015 7:04 PM

Computing a checksum is easy. Computing an Atari OS checksum is, ... it depends :-). I went through it deeper than originally expected.

 

http://www.wudsn.com...atariromchecker

 

atariromchecker-large.gif

 

 



#12 Kyle22 ONLINE  

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Posted Tue Jul 10, 2018 9:36 PM

Did anyone download that torrent I posted, I hope?   If so, please provide a link. I can't seem to find it now...



#13 _The Doctor__ ONLINE  

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Posted Tue Jul 10, 2018 10:14 PM

maybe you can get it back from foreign site... hope it's still in english....

 

http://www.warezik.e...e/t-365948.html

 

or maybe this is better... not sure.. might be usb not 232

 

https://www.daddytor...ts_2502560.html

 

or maybe russia.... just make sure to wear protection, the place crawls...  i saw kyle22 in two of these choices

 

http://7tor.org/view...c.php?t=1905288


Edited by _The Doctor__, Tue Jul 10, 2018 10:25 PM.


#14 Kyle22 ONLINE  

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Posted Tue Jul 10, 2018 10:25 PM

Yeah, I had am image ready made for it, just can't find it now. It's probably on an a hard disk somewhere with pictures of Loretta on it.

 

I SO want that stuff back... :)\



#15 _The Doctor__ ONLINE  

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Posted Tue Jul 10, 2018 10:27 PM

you posted at same time as my edit came through.... the last one might be it....



#16 Kyle22 ONLINE  

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Posted Wed Jul 11, 2018 1:27 PM

Thanks for the links Doc. Hopefully some seeds will show up.



#17 AtariGeezer ONLINE  

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Posted Wed Jul 11, 2018 3:27 PM

Re-Seeding now :)



#18 Nezgar ONLINE  

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Posted Wed Jul 18, 2018 11:12 PM

Initially I showed 0 seeds but sometime between then and now I got it all, and its re-seeding.. Here's the magnet link my client is currently showing to save others from going down the wrong rabbit holes of the Internet. :D
 
magnet:?xt=urn:btih:136EE376938AAB77442D6A1BEF20979261BF5E02&dn=NeowareProgrammer&tr=udp%3A%2F%2Ftracker.coppersurfer.tk%3A6969%2Fannounce&tr=udp%3A%2F%2F9.rarbg.to%3A2710%2Fannounce&tr=udp%3A%2F%2Ftracker.leechers-paradise.org%3A6969%2Fannounce&tr=udp%3A%2F%2Ftracker.pirateparty.gr%3A6969%2Fannounce&tr=udp%3A%2F%2Feddie4.nl%3A6969%2Fannounce




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