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The Commodore 64 Emulator with the extra dimension

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Commodore 64


The VIC II debugger lets you analyse what the 6569/6572 is doing at which 6510 CPU cycle. You can smoothly zoom in to see more detail - down to the executed CPU assembler commands.

Further more you can set breakpoint at any rasterline and single step through the running program. See short demo on You Tube

Select the view from the Views toolbar:
Switch to VIC debugger view


Double click left mousebutton to toggle a mark for rasterline and cycle
Click right mousebutton to toggle a breakpoint for a rasterline
Shift + left mousebutton and move up/down to zoom in/out
Left mousebutton and move to move view when zoomed in


The first zoomlevel shows the read color and pixel informations:
VIC debugger

The next zoomlevel also shows the "bad lines" and the ready states:
VIC debugger

The third zoomlevel shows the VICs memory access cycles, IRQs, adress changes and much more (see details below):
VIC debugger

The forth and fifth zoomlevel adds more details to the memory access cycles and the executed 6510 CPU assembler code:
VIC debugger


BA: Dark Red Background
Ready: Dark Green Background
Display enabled: Small light green rectangle on the right side
Display idle: Small light rect rectangle on the right side
M+ Screen mode changed
V+/- Vertical border flipflop set/cleared
H+/- Horizontal border flipflop set/cleared
D+/- DEN set/cleared
B+/- Badline condition set/cleared
X+/- BA set/cleared
R+ Rasterline IRQ line set
R> Rasterline IRQ set
R< Rasterline IRQ cleared
S> Sprite-Sprite collision IRQ set
S< Sprite-Sprite collision IRQ cleared
B> Sprite-Background collision IRQ set
B< Sprite-Background collision IRQ cleared
S& Baseaddress screen memory changed
B& Baseaddress bitmap memory changed
C& Baseaddress character memory changed
G$ G access cycle
C$ C access cycle
I$ I access cycle
CI$ CI access cycle
RC0 RC reset
MX Memory configuration changed (6510 IO port 1)
@P Sprite P Access
@S Sprite S Access
@+/- Sprite DMA on/off