View source for DMA interrupt enable 2

{{NextRegister
|Number=$CE
|Readable=Yes
|Writable=Yes
|ShortDesc=UART Interrupts that can override DMA
}}
  bit 7 = Reserved must be zero
  bit 6 = UART1 Tx empty
  bit 5 = UART1 Rx half full     \ shared
  bit 4 = UART1 Rx available     / interrupt
  bit 3 = Reserved must be zero
  bit 2 = UART0 Tx empty
  bit 1 = UART0 Rx half full     \ shared
  bit 0 = UART0 Rx available     / interrupt
* Set bits indicate the corresponding interrupt will interrupt a dma operation when in hw im2 mode

soft reset = 0x00

Because interrupts are only sampled at the end of an instruction by the Z80, each time the dma is interrupted one instruction of progress is made in the main program.