ok simple questions..
Re: ok simple questions..
they are pmode stuff. you really need to understand basics of pmode if your going to code an OS on x86 hardware.
(bootp is a network thing tho)
(bootp is a network thing tho)
-- Stu --
-
BLoggins02
Re: ok simple questions..
DF is right, he's got some info on the FAQ part of this site, also try the 80386 Programmers Reference Manual
(http://webster.cs.ucr.edu/Page_asm/Doc386/TOC.HTM)
Here's the quick rundown:
IDT: Interrupt Descriptor Table. ?A table with 8 byte entries that define how the processor handles interrupts. ?To write/get to the interrupt handler for interrupt n:
offset = IDT_BASE + 8 * n
GDT: Global Descriptor Table. In protected mode, this is also a table of 8 byte entries that define the segments your system uses. ?These entries are called segment descriptors. ?You can use these to implement protection, virtual memory (although most people use paging for this one), priviledge levels, etc. ?Segments are now 8 byte aligned starting with zero (dummy segment), so 0x08, 0x10, 0x18, etc
TSS: Task state segment. ?A processor-managed (and OS managed) data structure that defines the context (state) of the current task (including registers, protection level, segments, etc). ?When you jump to a TSS, the processor initiates a TASK switch, and saves the status of the current running task in its TSS, so you can resume that (or any task) at (almost) any time without losing the state of the task.
BOOTP: ?Cars, Bikes, Trains, Chickens??? Where did this one come from? ?Anyway, BOOTP is a protocol somewhat (vaguely) similar to DHCP in that it lets you grap network configuration info from a central server at boottime (or whatever time you need to reconfig your interface). ?NICS with BOOT(P)ROMS can actually use BOOTP to load and execute a file from the server at boot time, thereby allowing the implementation of totally diskless workstations.
I'm not the most accurate source for this information, don't take what I say as gospel. ?Check out the 80386 Manual listed above as well as other sources for info.
HTH,
Breckin
(http://webster.cs.ucr.edu/Page_asm/Doc386/TOC.HTM)
Here's the quick rundown:
IDT: Interrupt Descriptor Table. ?A table with 8 byte entries that define how the processor handles interrupts. ?To write/get to the interrupt handler for interrupt n:
offset = IDT_BASE + 8 * n
GDT: Global Descriptor Table. In protected mode, this is also a table of 8 byte entries that define the segments your system uses. ?These entries are called segment descriptors. ?You can use these to implement protection, virtual memory (although most people use paging for this one), priviledge levels, etc. ?Segments are now 8 byte aligned starting with zero (dummy segment), so 0x08, 0x10, 0x18, etc
TSS: Task state segment. ?A processor-managed (and OS managed) data structure that defines the context (state) of the current task (including registers, protection level, segments, etc). ?When you jump to a TSS, the processor initiates a TASK switch, and saves the status of the current running task in its TSS, so you can resume that (or any task) at (almost) any time without losing the state of the task.
BOOTP: ?Cars, Bikes, Trains, Chickens??? Where did this one come from? ?Anyway, BOOTP is a protocol somewhat (vaguely) similar to DHCP in that it lets you grap network configuration info from a central server at boottime (or whatever time you need to reconfig your interface). ?NICS with BOOT(P)ROMS can actually use BOOTP to load and execute a file from the server at boot time, thereby allowing the implementation of totally diskless workstations.
I'm not the most accurate source for this information, don't take what I say as gospel. ?Check out the 80386 Manual listed above as well as other sources for info.
HTH,
Breckin