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
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