|Re: OT: BASIC comparison sheet|
Message #11 Posted by Borja on 18 Jan 2009, 12:53 p.m.,
in response to message #10 by Marcus von Cube, Germany
I have an interesting fact about the PC-1430, another of the BASIC Sharp pocket computers.
I found something really funny, a buffer overflow condition that allows one to recover the password and access the program contents. It's a bit tricky and it corrupts part of the memory, but with this technique you can recover most of the protected contents.
The trick is to fill the complete input buffer (it's around 64 or 80 characters, I don't remember now). When you cannot add more, press the "INS" key repeteadly. Each time you press it, you will "insert" a character, which actually starts moving memory contents at the left of the cursor. You will see some curious characters, supported by the character generator in the computer, although not available on the keyboard. A frequent character is "~", which I guess is the representation of a 0 for that character generator.
If you keep pressing INS repeteadly for some time, more garbage will show, until you find a readable word (of course assuming that the user hasn't put a very weird password).
You Have found it, but it's been overwritten, most likely by the most frequently occuring characters in that memory zone, "~".
Now just clean up the input buffer, keeping eight "~", add the quotes around the new password ("~~~~~~~~"), and the PASS command at the left, press enter, and, voila!