scorpius.txt The Scorpius loader in extipl 5 is identical to the Extended-IPL version 4. Since large hard disks became inexpensive and Scorpius cannot load an OS at the end of a large disk, Scorpius may not be used much. We included this document because the default loader Gemini evolved from Scrorpius. 1. Using Scorpius on a Floppy Disk To install Scorpius on a floppy, insert formatted disk to A: and type extipl fdtest filename-of-floppy-drive @scorpius. Then Scorpius will be installed to floppy. Let's use Scorpius on floppy. Make sure that floppy drive is tried for booting before hard disk. Otherwise you cannot boot from floppy disk. Insert the floppy disk and reboot your computer. You should see your computer boot as usual. Scorpius boot OS as original MBR does unless shift key is pressed down. Reboot your computer and see when floppy disk is accessed for booting. Push down shift key when floppy drive starts reading. Then partition information and prompt "Boot#0:0.?" is displayed. In this prompt, the first 0 stands for hard disk unit 0 (first HD), the second 0 does the depth of the selected partition table, and ? stands for the partition selected for booting. You can select booting partition by typing 1--4. Hitting enter key boots OS in selected partition. A more detailed usage is given below. 2. Installing Scorpius onto a Hard Disk Booting from floppy is inconvenient. You may want to install Scorpius to HD once you convince that it is safe. To install it to HD, type extipl install filename-of-hard-disk @scorpius Then you are asked to what file MBR is backed up. After backing up, you are asked for final confirmation. Hitting `y' key allows Scorpius replace MBR with its own. If you want to stop installation, type Control-C. You must log in as root to do the installation. 3. Booting with Scorpius Scorpius exactly does same thing as original MBR does unless shift key is pressed down, i.e. it boots OS in the partition marked bootable. To select booting OS, press down shift key when booting. Then Scorpius displays contents of partition table and waits for your instruction. Below is an example. ------------------- Part Sys 1 s01 ;; partition NO. and partition ID (DOS) 2 sA5 ;; FreeBSD 3 s05 ;; (MS-DOS) extended partition 4 ;; empty partition Boot #0:0.2 ;; prompt ------------------- | | | | | +---- partition NO. | +----- the depth of the partition table +------ HD unit NO. Partition ID below "System" depends on what OS you install in HD. First selected partition is the partition marked bootable. In this step you can select booting partition by number 1--4 and hitting enter key starts booting. If you try to boot empty partition (4 in this case), you here beep sound and booting does not start. Booting also does not start if selected partition does not have 0xaa55 in 511th byte, which indicates it is a valid partition. Some OS does not boot if its partition is not marked bootable. Scorpius can mark selected partition bootable before booting. It can be done hitting end key instead of enter key. Scorpius has 2 kinds of booting key. They are <Enter> boot OS in selected partition. <End> mark selected partition bootable and boot OS in it. If you do not press shift key in next booting, this partition is booted. Scorpius can mark partitions bootable only in first HD. You cannot mark partitions in second or later HD bootable, or an extended partition. 4. Booting OS in the Second or Later Hard Disk Booting OS in non-first HD is not an official function of PC/AT compatible computers. Thus not all OS can boot from second or later HD. In stage of partition selecting, you can select them by inputting number 1 to 4. You can switch target HD by inputting 0. If you input 0, Scorpius displays contents of partition table of next HD. You can do the same thing with currently selected HD as first HD except end key. You cannot mark partitions in second or later HD bootable by end key. When you see the contents of partition table of second HD and hit 0, you will see that of third HD if you have it. Otherwise you will return to first HD. 5. Booting from an Extended Parition If you choose partition 3 in the example in 3.3, Scorpius shows the partition table in the extended parition 3. Below is an example ------------------- Part Sys 1 s83 ;; partition no. and system ID 2 s05 ;; 3 4 Boot #0:1.1 ;; prompt ------------------- In this example, the first partition in the extended partition is a Linux partition, and the second is an extended partition in the extended parition. If you select 1, you boot Linux. If you select 2, you enter the extended partition. In order to return to the primary partition, select 0 (switching hard drive) several times. 6. Tricky Use of Scorpius If there are no partitions marked bootable, Scorpius enters partition selection even if shift key is not pressed. If you want not to press shift key, you can exploit this feature. You can mark all partition not bootable by "extipl clrboot" command. If BIOS loader of MBR checks the validity of MBR strictly, it consider the MBR invalid and YOU BECOME UNABLE TO BOOT ANY OS IN YOUR HARDDISK. BE CAREFUL.