Wozu mit Goto zum Return springen? Einfach gleich ein Return rein.

Code:
$regfile = "m88Adef.dat"
$baud = 19200
$crystal = 8000000

Config Watchdog = 512

$hwstack = 160
$swstack = 100
$framesize = 100

Ddrb = &B00011100

Led1 Alias Portb.2
Led2 Alias Portb.3
Led3 Alias Portb.3

Config Int0 = Falling
On Int0 Isr_int0

Dim Bstop As Bit
Dim L As Long
Enable Int0
Enable Interrupts

Do
   Gosub Prg1
   Waitms 100                                               'entprellen
   Gosub Prg2
   Waitms 100                                               'entprellen
   Gosub Prg3
   Waitms 100                                               'entprellen
Loop
End

Prg1:

   Reset Bstop
   Do
      Toggle Led1
      For L = 1 To 1000
         Waitms 1
         If Bstop = 1 Then
            Return
         End If
      Next L
   Loop

Return

Prg2:

   Reset Bstop
   Do
      Toggle Led2
      For L = 1 To 1000
         Waitms 1
         If Bstop = 1 Then
            Return
         End If
      Next L
   Loop

Return

Prg3:

   Reset Bstop
   Do
      Toggle Led3
      For L = 1 To 1000
         Waitms 1
         If Bstop = 1 Then
            Return
         End If
      Next L
   Loop

Return

Isr_int0:
   Set Bstop
Return