Because your PowerBook 145B shipped with OS 7.1, it can't run an earlier version of the Mac OS, such as 7.0.1. Unfortunately, Apple never made OS 7.1 available for download. You can run OS 7.5.1, 7.5.3, and 7.5.5 on your PowerBook, but I'd recommend doing so with the maximum amount of supported memory - 8 MBs. The 19-part download of OS 7.5.3 is segmented, so that each one will fit on a 1.44 MB floppy disk. The problem is that the 19-diskette set isn't an installer set as such, having no bootable disk. It's solely intended to be used to transfer the individual segments to the resident hard drive in the computer. Once that's done, double-clicking the first .smi segment creates the OS 7.5.3 installer disk image on the desktop, which you drag onto the hard drive icon. This produces a folder with the OS 7.5.3 installer in it. I've done this before with an old Mac LC and it works. You can also download the 3-diskette OS 7.5.5 Update and run that. These downloads can be found on the same page where you found the OS 7.0.1 download: Older Software Downloads.
When you say it won't boot do you get a folder with a ? in it or nothing? Reason I ask is that the hard drive itself may be bad or stuck from sitting for a long time. If you can hear it spinning up or spinning then the HD is working but if you don't hear anything you might need to take out the drive and swish it gently back and forth a couple of times to unstick it. NO hard knocks.
Thanks for theh help, I didn't know it was 7.1 was the original OS.
The thing is, I can't get to the harddrive of the PowerBook, so there is no chance for me to get the 7.5.3 files on it. It needs to be re-installed if I'm going to get that to work.
Any idea how I can fix this? Can I pop out the harddrive and re-frm it?
I get all the normal things, but when it's supposed to load the message "The "System" file on the startup disk may be damaged. The installer can be used to repair this disk."
If I put in a 7.0.1 install floppy it boots from it but then it comes up a warning-window but its totally white and the screen start flickering.
You may want to try another startup floppy for a test. Use, for example, the Network Access Disk 7.5.
Make sure that you are using Disk Copy (the Make A Copy button in version 4.2, or the Make a Floppy command in 6.3.3) in order to create a correctly sector-copied disk from the downloaded image.