I have a strange behaviour in EP128Emu.
When I unlock the interrupts with EI after there is already an IRQ the following happens:
- the next command after EI will be executed; this is correct
- new #38 is called, which is correct, too
- BUT: instead of having the address of the next command on the stack I have this address increased by 1

Example:

#1000:  EI
#1001:  LD BC,#1006
#1004:  PUSH BC
#1005:  JP (HL)
#1006:  ...
The IRQ happens between LD BC,#1234 and PUSH BC.
The return address in the Stack should be #1004 now.
But it is #1005. PUSH BC is just skipped, when the IRQ returns
When I add a NOP after the LD BC,#1006 it works...

I tried to reproduce the problem with this code entered in the monitor while IS-BASIC was running:


However, after setting a 0038x breakpoint and starting the code with G FF0, the return address on the stack was always 1004h. I do not know exactly what conditions could trigger the bug, but it cannot be common, because something basic like this being broken would otherwise cause a lot of crashes.