Z80/
LABVIRTUAL MICROCOMPUTER
64 KiB RAMWebAssembly · local executionHelp & guideLOADING
Starting Z80 WebAssembly engine…
SessionKeep your CPU, RAM, source, breakpoints and terminal together

Serial terminal

Ports 00 · 01 · 02

        
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CPU state
Zilog Z80

        

          
Main registers

            
A 00
F 00
B 00
C 00
D 00
E 00
H 00
L 00

          

          
Alternate registers

            
A′ 00
F′ 00
B′ 00
C′ 00
D′ 00
E′ 00
H′ 00
L′ 00

          

        

        
IX 0000
IY 0000
SP FFFE
PC 0000
I 00
R 00
IM 0
IFF 0/0

        
S 0Z 0Y 0H 0X 0P/V 0N 0C 0

        
Instructions 0T-states 0

      

      

        
Disassembly
Following PC · 12 instructions

        

        

        
0 active

        
Click a disassembly line to add/remove a breakpoint. Run again to continue past a breakpoint.

      

      

        
Memory inspector
128 bytes · hex + ASCII

        

        

        
Edit RAM CPU pauses before writes · hex bytes only

      

    

    
Load programLocal files never leave your browser

      
or

    

    

      
Assembly workspace
ASM80 · assembles locally in your browser

      

        
        
        
        
      

      

        

          

          

        

        
Assemble to see addresses and generated bytes.

      

      
Assemble & load to enable source-level debugging. Click a mapped line number to toggle a breakpoint.

      
Assembler bundle loading…

      
Shortcuts: F5 Run · Shift+F5 Pause · F10 Step instruction · F11 or Shift+F10 Step source · ⌘/Ctrl+Enter Assemble & load. Click an assembler error to jump to its source line. ORG sets the load address. The first emitted address (or explicit END entry) becomes PC. Loading resets CPU/RAM and clears breakpoints. Source debugging uses ASM80's emitted line mapping: only emitted row starts accept source breakpoints. Editing source or loaded code invalidates the map. Single-file ASM80 syntax; Pasmo compatibility is not guaranteed.