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Modifying io.sys: boot floppy

ram_einstein
ram_einstein asked
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Last Modified: 2007-12-19
Hi,

I created a custom boot floppy by modifying (+ adding and deleting a few files) the standard Win98 boot disk. It contains a variety of files including msdos.sys, io.sys, command.com, config.sys and autoexec.bat

I modified config.sys, autoexec.bat and help.txt to suit my needs. When I changed my boot sequence to Legacy floppy, the floppy succesfully registered and displayed:


Starting Windows 98....                                  <-- THIS


Windows 98 Startup Disk                                <-- AND THIS
================

1. Use Custom boot disk                                  // MODIFIED
2. View Help file                                             // MODIFIED


As you can see, I managed to modify the lines marked 'MODIFIED' but wasn't able to modify the lines marked 'THIS'

I figured out that these two lines of text are controlled by io.sys by method of elimination. So I opened io.sys in an ASCII text editor (notepad). Half of it was in the form of junk characters so I figured out I couldn't modify it that way. Is there any other way to modify it?

Thanking you for your time,

Ram
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Commented:
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Thanks pbarrette. Not to mention that the string can be less than 22 characters, but the remaining characters must be spaces 0x20 in HEX.

Author

Commented:
Hi all,

I am really sorry for not responding earlier but my comp crashed and now I have a bigger problem: Linux. I promise I will get back as soon as I can and analse these answers.

(https://www.experts-exchange.com/Operating_Systems/Linux/Linux_Setup/Q_20931614.html)

Regards,

Ram

Author

Commented:
Hi HKCU,

I saw the code of fbd.bat:
"uses %1 parameter to enter the drive letter of the floppy drive" (comment)
I don't know what that means. I tried shelling command and typing fbd %1. fbd started succesfully but what is %1? I even tried fbd %a but it kept returning the same error: unable to complete format. I guess I haven't enetered the floppy drive letter in the correct format. How do you enter it?
The rest is a piece of cake. Thanks a lot.
************************************************************
Hi gtkfreak,
I don't know what NU is so I tried using debug and figured out I don't know how to use it. I don't know what comes after debug io.sys. I tried the help but it isn't very helpful either. So i downloaded the hex editor I always use: Hackman. I'll try using it and get back to you.
************************************************************
Hi pbarrette,
If the file is difficult to modify (like critical size etc.) how was it made in the first place? But yes, I will keep what you said in mind.

Regards,

Ram

Author

Commented:
:(

How do I use a hexeditor to modify the strings in io.sys? Hex displays the file in hex characters, binary in binary and so on. ASCII displays the junk characters an ASCII text editor like notepad would display. What do I edit in the hex mode?

Ram
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Author

Commented:
HKCU's answer is a roundabout method: besides if what pb says is true, I can't write to the HDD. I prefer the hexeditor method suggested by gtkfreak. Thanks for that last comment pb: I failed to notice the right panel earlier! Mot to mention the critical size, advice on how to replace letters etc.

Thanks a lot for all your comments,

Ram
Hi R_E,

Glad to help,

pb
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