You are confusing the way BIOS supports a USB keyboard (and mouse?) with the general case. The USB host controller uses a single interrupt. Software then demultiplexes that to handle interaction with a specific USB device. Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) ----- Original Message ----- From: "William Tan" To: Sent: Tuesday, June 19, 2001 9:43 PM Subject: Re: [OT]:Some doubt about USB device. > Sorry for asking another question.... > > So, if so motherboard support USB/keyboard (hardware-level emulation), then is > the keyboard will still taking the IRQ1 and PS/2 mouse takes IRQ12 ....??? > > Then, how come people said that USB device won't need IRQ? > > For standard PC, there are just 15 IRQs. Now, most of them are used up. For an > example, if my PC is attached with a lot of USB device (let said USB 10 > devices and 2 USB 7-port hubs ), then if not enough IRQs, then how those USB > devices talk to the PC (host)??? > > Thank you. > > regards, > William > > > > Bob Ammerman wrote: > > > Some PCs have BIOS support for USB mice/keyboards - I believe that this is > > to the extent of providing hardware-level emulation of the legacy devices. > > > > Bob Ammerman > > RAm Systems > > (contract development of high performance, high function, low-level > > software) > > > > > Dear All, > > > > > > (1) If USB mouse or USB keyboard is used under Windows environment, they > > > can easily be detected. Then, if I use USB mouse and USB keyboard in > > > DOS, then how can both of them be detected? > > > > > > Or, if I buy a new DIY PC with USB mouse and USB keyboard, then, how can > > > I configurate my BIOS and setup my Windows OS (before any USB driver can > > > be loaded)? Then, it seems that I also need (or borrow) standard > > > keyboard .....??? > > > > > > ------------------- > > > > > > (2) Then, can USB be the futher peripheral interface? > > > > > > regards, > > > William > > > > -- > > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu