Nukey Shay Posted May 19, 2004 Share Posted May 19, 2004 What does JAM @ 1822 mean? Quote Link to comment Share on other sites More sharing options...
Tom Posted May 19, 2004 Share Posted May 19, 2004 http://www.xmission.com/~trevin/atari/6502...2_insn_set.html search for jam on that page. i guess 1822 is the address where the instruction occured. Quote Link to comment Share on other sites More sharing options...
Eckhard Stolberg Posted May 20, 2004 Share Posted May 20, 2004 This is correct. Some of the undocumented inteructions on the 650x type processors will crash the CPU. These are generally referred to as 'JAM' instructions. The 6507 can only address 8K or memory, so address $1822 could also be $F822, depending on where the code was ORGed to. This error message in z26 usually means that you are using the wrong bankswitching format for the game or that the reset-vector was not set correctly in the ROM. Then z26 might try to execute some data as code and encounter a 'JAM instruction' in there. Ciao, Eckhard Stolberg Quote Link to comment Share on other sites More sharing options...
Nukey Shay Posted May 24, 2004 Author Share Posted May 24, 2004 I can't figure it...after moving things around, I get a message JAM 02 @ f561. Yet at $F561, I put a NOP instruction (to try to trap that error)...that opcode is $EA Moving things around in the 2nd bank will change the message, so it's confimed that it's not the first bank generating the error. Try this and eat the red/pink monster (they are set to move together to test while trying to eliminate this error). The moment you do, that error will appear. Is there no chance that error isn't meaning something else? It should land on a NOP if it's supposed to mean the address. Or is there some other factor that might report the incorrect address? error.zip Quote Link to comment Share on other sites More sharing options...
Cybergoth Posted May 24, 2004 Share Posted May 24, 2004 Hi there! Have you tried enabling the log? Just look at the last few instructions. Such an error should end like JMP($$$$) or READ($$$$) (B/S Hotspot)... It also happens for example when not all ORGs in the second bank are RORGed... Greetings, Manuel Quote Link to comment Share on other sites More sharing options...
Nukey Shay Posted May 24, 2004 Author Share Posted May 24, 2004 Nevermind. It was due to the table near the end of the file being read with a too-high Y offset...causing the machine to bankswitch when trying to read from $FFDE+Y ($FFDE+$1B=$FFF8) Quote Link to comment Share on other sites More sharing options...
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