mike.irons@lynx.northeastern.edu (10/18/90)
I have a quick question. I am trying to make more room for a server that I am adding to my PC Minix1.5 and am having trouble with overwriting my bootblok while it is loading in Minix. What is the furthest up in memory that it can go. I have gotten it to mov up to 0x9700 but any higher and after db runs I don't get the menu, but just the line of text from the bootstrap, and then it dies. Is this the upper limit of bootblok, or should I be able to move it to 0x9FA0 (originally it's at 0x8FA0). mike.irons%lynx@helios.northeastern.edu
evans@syd.dit.CSIRO.AU (Bruce.Evans) (10/23/90)
In article <33867@nigel.ee.udel.edu> mike.irons@lynx.northeastern.edu writes: >I am adding to my PC Minix1.5 and am having trouble with overwriting my bootblok >while it is loading in Minix. What is the furthest up in memory that it can >go. I have gotten it to mov up to 0x9700 but any higher and after db runs I >don't get the menu, but just the line of text from the bootstrap, and then it >dies. Is this the upper limit of bootblok, or should I be able to move it >to 0x9FA0 (originally it's at 0x8FA0). db moves itself to about 0x9780 (in units of hardware-click). bootblok takes 0x60. So limit is about 0x9720. You could only put it at 0x9FA0 in a standard Minix setup where db is not loaded. The right way to determine the memory size is to make a BIOS call like the kernel. There is no right way to change the memory size :(. db does it by changing the BIOS variable at 0x40:0x413. bootblok could do the same, but it's best that it doesn't since 0x600 bytes would be wasted. bootblok should be looking at the memory size to see how high it can load itself. Then minor adjustments to bootblok+db would be required to stop db clobbering bootblok. -- Bruce Evans evans@syd.dit.csiro.au