Thursday, January 16, 2014

68k project: step II - execute some bytes by 68008 taken from AVR, actually!

[original article - http://xepb.org/dtz/68kavr.html ]
The scheme for Running first program


XEPb.org is down again! Welcome in few days




The GCC source or AVR program


The result of running program:


(* is a clock tick , is a comment)
************************************************************************************************************************************
********************************************************************************************
Calling release reset
[Released reset]
**************************** clock after reset
INT: R Int happens when /DS goes low; R means that CPU is READING
State 0000***** "State 00" is some debug message, the other byte is actual byte
Releasing bus*** 5 clock changes /DS from low to high; 'Releasing bus' - MCU put data bus to high impedance.
INT: R
State 0000*****
Releasing bus***
INT: R
State 0000*****
Releasing bus***
INT: R
State 0008***** fed with 00000008; really the address does not matter, but it must be even, as you understand ;-) -
Releasing bus*** the first thing I've got was a trap leading write 14 bytes to somewhere
INT: R
State 0000*****
Releasing bus***
INT: R
State 0000*****
Releasing bus***
INT: R
State 0000*****
Releasing bus***
INT: R
State 00C0***** fed by stack pointer
Releasing bus***
INT: R
State 0020*****
Releasing bus***
INT: R
State 007C*****
Releasing bus*******
INT: R
State 0000*****
Releasing bus***
INT: R
State 0000*****
Releasing bus***
INT: R
State 0000*****
Releasing bus***
INT: R
State 0000***** fed with movea.l #0,A0
Releasing bus***
INT: R
State 0020*****
Releasing bus***
INT: R
State 003C*****
Releasing bus***
INT: R
State 00AA*****
Releasing bus***
INT: R
State 0055*****
Releasing bus***
INT: R
State 0033*****
Releasing bus***
INT: R
State 00CC***** fed with move.l #$aa5533cc,D0
Releasing bus***
INT: R
State 0020*****
Releasing bus***
INT: R
State 0080***** move.l D0,(A0)
Releasing bus***
INT: R
State 004E*****
Releasing bus***
INT: R
State 0071***** fed with NOP - that's prefetching
Releasing bus*****
INT: WAA******** Writing data! Whuuuuaaaaaauhuhhhh!
INT: W55********
INT: W33********
INT: WCC******
INT: R
State 004E*****
Releasing bus***
INT: R
State 0071*****
Releasing bus***
INT: R
State .....




So, we see that at least one command was executed by CPU

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