Calculator

[www.atarimania.com]

Courtesy of John Hardie again, here's an original cartridge prototype of Carol Shaw's Calculator by Atari:

http://www.atarimania.com/utility-atari-400-800-xl-xe-calculator_33786.html

 

Note the different copyright line at the top of the screen compared to the program released on disk!

[DrVenkman]

Interesting. In conjunction with Kay’s interview with Carol Shaw, he got her handwritten design notes and the source code printouts, which have been digitized and put up on Github. I wonder if there’s anything significantly different in the code compared to the cartridge binary?

 

[www.atarimania.com]

Yes, it would definitely be interesting to have some sort of comparison chart if there are differences in the code.

[jindroush]

BTW Currently I have three binaries - other cart (blue background 1979, 16k), this cart (pinkish 1979, 8k) and this xex (pinkish 1979, 8k). The two carts have completely different memory layout, but I have no clue where I got it from.

[www.atarimania.com]

Isn't the cart with the blue background a fake ROM created by Peter Dell? I think the .xex file is just a crack of the program released on disk.

[Mathy]

.

Hello guys

 

Why not ask @JAC! himself?!   (Who BTW is sitting not 5 metres from me at the moment 🙂  and should be online as we speak)

 

Sincerely

 

Mathy

 

Edited May 20, 2023 by Mathy

[+DjayBee]

13 hours ago, www.atarimania.com said:

Yes, it would definitely be interesting to have some sort of comparison chart if there are differences in the code.

What is CALCULATOR.XEX in your ZIP archive?

It differs completely from CALCULATOR.CAR.

 

Found it out myself: The AUTORUN.SYS from the APX release.

Edited May 20, 2023 by DjayBee

[www.atarimania.com]

The Atari and APX disk releases are different then? The main file, I mean.

Edited May 20, 2023 by www.atarimania.com

[+DjayBee]

14 minutes ago, www.atarimania.com said:

The Atari and APX disk releases are different then? The main file, I mean.

Now I'm confused (or don't know it correctly).

I thought there was only an APX release.

 

I rephrase: The XEX is identical to the AUTORUN in Atariwiki's ATR image.

 

Meanwhile I am also a bit farther in analyzing the CAR: It seems to be identical to the XEX except:

• "Transposed" from $3C00 to $A000.
   
• Different title text on screen. (The implementation is weird.)
  The first two screen rows are contained in the code in obfuscated form but the disk version skips the title row and replaces it with plain text taken from a binary load segment which is attached at the beginning of the file.
  If you replace starting at offset $180 in the XEX with this code, you will receive the same text as in the CAR (see attached XEX):

  XEX  : 82 20 E4 3F 20 B9 45
  Patch: 58 A0 3B EA 20 53 3B

   

• The CAR does some calculations around MEMTOP.

I only did a binary diff and did not disassemble the files completely.

Besides the above differences there are only single-bytes differing - just like it is expected when program code has been moved from $wx00 to $yz00.

This is the reason for my assumption that there were no other changes made.

Calculator-reverted.xex

[+JAC!]

4 hours ago, www.atarimania.com said:

Isn't the cart with the blue background a fake ROM created by Peter Dell?

Please mind your words before calling something a fake. My cartridge was created as personal gift for Carol. It is explicitly based on the released disk version and includes a complete DOS, so I can be used reasonable even you do not have a disk drive (which was the case for her).

https://www.wudsn.com/index.php/productions-atari800/tools

[www.atarimania.com]

Sorry, my bad for the poor choice of words but no need to get all worked up... Things are explicit if you piece everything together but it isn't that obvious to me on the AtariWiki page...