Disected! - A disk sector editor in BASIC

DIsk SECTor EDitor

Mar 10

I wrote about Atari DOSes in this week’s Monday paid post and I continue that topic with a program I wrote back in 1985 called Disected!

It is a DIsk SECTor EDitor and I have to say, I’m kind of proud of that name. It is entirely based around a single machine language routine

that is built into the OS to read a sector of data from a disk. With this single routine you could build your own DOS if you wanted to, although certainly not in BASIC.

Disected

4.77MB ∙ PDF File

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As I typed the program in, a couple things jumped out at me. First is the FOR loop on line 160 that does not have a corresponding NEXT. Looking at the code, I don’t even think the FOR loop is even necessary since the string is cleared using the subsequent code.

I also incorrectly used “then” instead of “than” (line 700). I hate that.

Also, when reading a sector in the Atari CR is changed to an asterisk for display purposes. When writing the sector back out, the asterisk is changed to a CR. So if the sector actually had a valid asterisk in it, it would get changed to a CR, corrupting what was there.

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Although this is less than 100 lines of code, there is a lot of jumping around and repeated code. Of course, Atari BASIC doesn’t make it easy to reuse code and it all line-based BASICs make it hard to refactor code once it’s written.

I seem to also have an even more advanced version of this, called 1050 Disk Ed (not as good a name). I have not yet typed this one in as it is much longer, but if memory serves it uses the joystick in some way.

1050disked

6.27MB ∙ PDF File

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