using RAD: as memory

[Piru]

Can I change the regular RAM disk to retain files like the RAD: disk?

No.

Can I increase the size of the RAD: disk and still retain the files?

Yes. Check the RAD icon tooltypes (highcyl). The default is 79, which gives you 880KB. So 1 cyl is 11KB. Thus for example to get roughly 2MB RAD, you would use highcyl of 2048/11 = 186.

Why does RAD: only retain files when it thinks it is a regular disk and not when it is just plain ol' RAD:

It should always retain the files, regardless of how you use it.

I suppose I can create many RAD: disks.

Correct. Just use unique unit for each.

[Piru]

I wonder why RAM: cannot be told to retain like this? Is it some deep hard coded software issue or some thing to do with how MOUNT works?

RAD is specially coded to retain the contents, RAM is not.

However, you can look into replacements, such as statram.

[Piru]

I just tried to use the regular format command to get my 2MB RAD: HD up and it tanked my system.

That sounds more like problem with your system. Bad memory or something.

Is there a special command or other program I should use to format a non-standard size?

No. Any size is equally standard.

Ah, and BTW: You don't need to format RAD, just initialize the filesystem. "Format DRIVE RAD: Name Foo FFS QUICK" should do the job.

[Piru]

hm, could you use other filesystems like PFS or SFS as well?

Yes.

would there be any advanage?

Very little.

except for fast warm reboots (which happen not-so-often here) is there some other uses of spending RAM on RAD?

Well, back when I only had A500 with two floppy drives, I used to have SAS/C main disk on RAD: ... includes on one floppy, and 2nd was the project disk ;-)