Hi Thanks to pa2ab, it is SOLVED: Current result: [root@pc2 ax25]# more /proc/interrupts CPU0 0: 237953 XT-PIC timer 1: 28 XT-PIC keyboard 2: 0 XT-PIC cascade 3: 1436 XT-PIC serial 4: 150467 XT-PIC AX.25 SCC 8: 2 XT-PIC rtc 11: 13220 XT-PIC eth0 12: 3428 XT-PIC PS/2 Mouse 13: 1 XT-PIC fpu 14: 22550 XT-PIC ide0 NMI: 0 My problem was I forgot I had the USCC card on IRQ4. Moved the comport to IRQ 3 instead, /dev/ttyS1 is now doing what I want. kissattach now works. 73 Kjell