From: Nicolas Welte; address is valid for replies (Re:) only! (welte_spam_at_freenet.de)
Date: 2003-02-16 18:03:15
Another strange ROM code turned up that makes my Flash hardware behave badly,
Wolfgang Moser found it when testing his special version of a Speeddos ROM,
based on the patchlevel of the 1541-II. But virtually every standard Speeddos
ROM contains the same code (disassembly from d65):
FF6D LFF6D:
FF6E LFF6E = * + 1
; Instruction parameter jumped to.
; this is actually a "hidden" BPL FFB1
FF6D 8D 10 41 STA L4110
FF70 LFF70:
FF70 AD 0C 18 LDA L180C
FF73 29 08 AND #$8
FF75 D0 03 BNE LFF7A
FF77 LFF77:
FF77 4C 16 E9 JMP LE916
FF7A LFF7A:
FF7A 20 B7 E9 JSR LE9B7
FF7D 9D 67 FE STA LFE67,X
; this is the offending instruction. It doesn't seem to be
another hidden instruction, though speeddos uses LDA and STA at other places
to hide stuff. Maybe it's only a strange coincidence, but $FE67 is also the
interrupt service routine.
FF80 A9 01 LDA #$1
FF82 LFF82:
FF82 2C 00 18 BIT L1800
FF85 30 2A BMI LFFB1
The code is only executed if the parallel cable is connected, and I could
make no sense of that instruction (nor could Womo). Any ideas, anybody?
Nicolas
Message was sent through the cbm-hackers mailing list
Archive generated by hypermail 2.1.6.