25
votes
Accepted
How are the randomizer values on the Apple II maintained?
It's incremented while waiting for keyboard input.
The 16-bit random seed (RNDL and RNDH) is updated by the KEYIN routine as it spins while waiting for a key press. KEYIN is used by the Monitor ROM's ...
- 641
22
votes
Accepted
How did the Apple IIe convert to upper case?
This is actually done as part of the Applesoft tokenizer. Basically when you type a line of code into the Applesoft interpreter, the very first thing that happens is that the line is tokenized -- it ...
- 416
11
votes
Accepted
Help understanding TAIPAN source code for the Apple II
You don't need to follow the listing far to see the problem.
Line 10 ends with GOTO 10000, and 10000 starts with CALL 6147, which is $1803, smack in the middle of the Applesoft source code, which ...
- 7,418
11
votes
How did the Apple IIe convert to upper case?
This post has a brief history of Applesoft. You'll note it was modified in 1984 to allow entry of lower-case keywords.
If you look at the PARSE routine (at $d56c) in the ][+ version of Applesoft in ...
- 8,775
8
votes
How did the Apple IIe convert to upper case?
[Oioioi, this is one of the darkest corner of the II line :))]
How did the Apple IIe convert to upper case?
The Apple IIe did not convert at all. That's why the IIe Programmers Reference mentions:
.....
- 213k
7
votes
Accepted
Did any AppleSoft language enhancements patch CHRGOT?
Yes, programmers occasionally patched CHRGOT. It wasn't a common tactic because there were better ways to add user-defined commands and functions, but you might choose to patch CHRGOT if you wanted ...
6
votes
Help understanding TAIPAN source code for the Apple II
You might have more luck with the BASIC program from this disk: Taipan Hayden Book Version, which was apparently keyed from the Taipan: A Historical Adventure For The Apple Computer book.
It at least ...
- 20.5k
6
votes
Examples of floating-point numbers that don’t round-trip losslessly through text conversion in Microsoft BASIC
Once you know the underlying implementation, it’s not too hard to come up with numbers that neither correctly parse, nor losslessly print back. All examples below use Commodore 64 BASIC V2, which is ...
- 21.6k
5
votes
Extensions to Apple BASIC with ampersands
A little late to the party but I remember doing this back in the early 80's, it was definitely the & "extension" used in Applesoft. Like Patrick mentioned I also remember combining ...
- 51
3
votes
Accepted
Why did ProDOS trace Applesoft?
IIRC using trace serves two purposes, both related to stability and performance:
Improving command detection
With TRACE enabled BASIC prints the line number `prefixed by a '#' character and suffixed ...
- 213k
3
votes
Motivation for DOS 3.3 using I/O hooks rather than ampersand-hook
As usual History and compatibility.
The Apple II was originally only released with Integer BASIC in ROM. Applesoft BASIC had to be loaded to RAM - not to mention that it was far from what we know, for ...
- 213k
2
votes
What books did schools use to teach BASIC?
"101 BASIC COMPUTER GAMES" also known as "BASIC COMPUTER GAMES" (the "101" in the title was not clear on some version of the cover art).
https://en.wikipedia.org/wiki/...
- 287
1
vote
Examples of floating-point numbers that don’t round-trip losslessly through text conversion in Microsoft BASIC
I'd like to address this bit:
Why not parse the number once, when the user enters the line, and
store the number in binary?
As you noted, such conversions can result in "oddities" (there's ...
- 19.5k
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