PC873_LPTBIRQ7
irq = (ptr & PC873_LPTBIRQ7) ? 7 : 5;
outb(idport + 1, (ptr | PC873_LPTBIRQ7));
outb(idport + 1, (ptr | PC873_LPTBIRQ7));
outb(idport + 1, (ptr & ~PC873_LPTBIRQ7));
outb(idport + 1, (ptr & ~PC873_LPTBIRQ7));