Hacker News Reader

Comment by DonHopkins | Hacker News Reader

    ]INT
    >CALL -151
    *F666G
    !0: INX
    0000- E8 INX
    ! TXA
    0001- ·8A TXA
    ! JSR $FDED
    0002- 20 ED FD JSR $FDED
    ! JMP $0
    0005- 4C 00 00 JMP $0000
    ! BRK
    0008- 00 BRK

https://www.callapple.org/vintage-apple-computers/apple-ii/a...

View on HN

Interesting. Looks like $FDED maps to a CHAROUT routine on the Apple ][, so this should print out the character map in an endless loop?

That's right. My "go-to" obnoxious assembly language program I could type in from memory was an infinite loop that screeched the speaker by loading my favorite io address $C030 at an ultrasonic rate.

    !0: LDA $C030
    ! JMP $0

I had a similar one I'd type in hex at $300, something like: CALL -151 300:B5 00 20 ED FD E8 AD 30 C0 4C 00 03 300G (that's a recreation I just worked out, but I think what I used to use was a little different - I forget what technique I used to use to get a semi-random character in the accumulator for it to print)

This filled the screen with scrolling garbage while buzzing the speaker.

Thank you Don! I was going to comment that I wrote a 6502 assembler in Logo for the Apple II and the C64 and it shipped with it and it was documented how to write in assembler. I was hoping to hear some kid learned 6502 assembler from it. That counts you out since you already knew 6502 assembler.

Reply on news.ycombinator.com