From mboxrd@z Thu Jan 1 00:00:00 1970 From: acahalan@gmail.com (Albert Cahalan) Date: Sat, 12 Nov 2005 01:13:47 -0500 Subject: [TUHS] Redoing "V6on286" or porting V7...? In-Reply-To: <849b04683754b84f7e42810d761db3bd@coraid.com> References: <849b04683754b84f7e42810d761db3bd@coraid.com> Message-ID: <787b0d920511112213q7156614cv2fe3c5d00852f45c@mail.gmail.com> On 11/9/05, Brantley Coile wrote: > my suggestions are as follows (i assume you really mean 8086 mode): That wouldn't be a good match. I believe you want this: * 16-bit * protected mode * no paging * 8 or 16 segments * 128 kB of the memory * no FPU > using a floppy to boot is a great idea. i've written several boot > straps to boot from the floppy that configure the serial port, and put > the processor in 32-bit mode. it's tight, but not too hard. you have > a great advantage in that you're going to stick to 16 bit so you can > use the bios. 512 bytes in that case is tons of space. 512 is easy until you try to handle more than one machine. :-( > next you'll need to write device drivers for the screen/keyboard, the > clock, and the floppy. later you can write an ATA driver and get a > mbr and hard disk boot strap. I think you need a 4 MB disk and a 10 MB disk. :-) > if you want to do a 32-bit version, then things are a little > different. but this should give you the v6 in about as little > work as can be. You might use a 32-bit CPU in 16-bit mode. Then you could use a 32-bit limit on the FS or GS segment for easier physical memory access from the kernel. (use an opcode prefix as needed)