I know what DIP switches or configuration pin headers do. For one, I've never heard them referred to as DIP PIN switches like PIN is some kind of acronym - perh

I know what DIP switches or configuration pin headers do. For one, I've never heard them referred to as DIP PIN switches like PIN is some kind of acronym - perhaps DIP pin switch is some kind of regionalism. But that was not the confusion: >> "Ask a new hot shot programmer to do dip-switches and IRQs etc"... Ok. >> let alone be able to tell you a PIN switch on a mobo for IRQ settings (PRE IPv4) After the first part about dip-switches and IRQs this makes it sound like "PIN switch" is something distinct. Further confusing, I still have no idea what PRE IPv4 means here. The only IPv4 I've heard of is internet protocol and not something I would associate with PC hardware configuration. (IPv4 was released pretty much at exactly the same time as the original IBM PC in 1981). > IRQ3 was typically the modem IRQ3 was more specifically the 2nd set of serial UARTs COM2/COM4 - with the IO base port assignment 2F8h and 2E8h. COM1/COM3 was IRQ 4 (base ports 3F8h, 3E8h). So a modem may very well been on IRQ 4. In practice it was often dependent on whether one was a using a serial vs PS/2 mouse.