Bugs in "Refactoring" BASIC code

[thecloudexpanse]

@mdcramer
I attempted to replicate your program on my Apple //e as well as the "Mariani" emulator, given the BASIC source code presented on https://mdcramer.github.io/apple-2-blog/refactoring/ and with the understanding that this builds on the code from https://mdcramer.github.io/apple-2-blog/synthesizing-data/ where some lines could be renumbered. A few problems showed up.

On line 1250, there is a missing % character which causes data to be incorrectly plotted. Here's a diff for the fix:

- 1250 HPLOT X0%,X1% - 1 TO X0%,X1 + 1
+ 1250 HPLOT X0%,X1% - 1 TO X0%,X1% + 1

Second issue is that you are overwriting the index variable 'I' in the Generate Samples loop by calling a subroutine which clobbers it. Line 460 declares a loop in which I starts at 0 and should be incremented to NS-1. Inside the loop, line 580 calls a subroutine at line 1400. That leaves the value of I set to 12 on exit, and so the loop is stuck forever at that index. I fixed this by changing the index variable in the Irwin-Hall subroutine, so it doesn't re-use I:

- 1500 FOR I = 1 TO 12
+ 1500 FOR IH = 1 TO 12

[mdcramer]

@thecloudexpanse , thank you! First, if you wouldn't mind, how did you find this? I never anticipated that anyone else would try to run this code, so this is exciting. I'm not familiar with https://emulationrealm.net/downloads/emulators/mac-os/computer-os/apple-ii/mariani (I'm assuming that's what you're using) so will check that out.

As you might have seen on https://mdcramer.github.io/apple-2-blog/emulator/, I'm getting the code off my Apple ][+ to my taking screen shots with my phone and then sending them through chatGPT. It's not perfect so I try to double-check, but you just made a couple excellent catches. I'll fix both of those with the next push.

[thecloudexpanse]

@mdcramer Mariani is basically a macOS port of AppleWin. If you're on Windows, you probably want to look into AppleWin first. The ChatGPT screen shot method is certainly error-prone. I use ADTPro https://www.adtpro.com to transfer files between the Apple II and a more recent machine. If you don't have a serial card or a way to connect it to USB, you can use plain audio cables from the Apple II's cassette ports to the modern machine's headphone and microphone jacks.

I first saw the mention on HN: https://news.ycombinator.com/item?id=45415510. I realized I had to start with your first post at https://mdcramer.github.io/apple-2-blog/synthesizing-data/, so I pasted those code snippets into a text editor and then into the emulator. Then I moved on to https://mdcramer.github.io/apple-2-blog/refactoring/. First thing I noticed was that instead of plotting a '+' for the first half of the samples, a vertical line was drawn from the top of the screen. That suggested one of the endpoint coordinates was 0, so I stared at the HPLOTs until I saw the error.

[mdcramer]

Oh wow. ADTPro looks very cool. I'll need the audio cable hookup but this looks like a great idea! It could also solve my problem of having to generate data on the Apple ][+. I'll have to dig into this when I have a free weekend.

Also, thanks for pointing out the Hacker News post! I put that on there and had no idea that it had received any attention. There was some good feedback in there which I incorporated into my blog. Anyway, it's running great on my machine so let me see if I can find any other errors in my chatGPT scanned code...