• Updated 2023-07-12: Hello, Guest! Welcome back, and be sure to check out this follow-up post about our outage a week or so ago.

RAM disk size limit

onlyonemac

Well-known member
Since my Perfomra 475's hard disk appears to be broken :( , I had decided that there was another way I could use my mac. My plan was as follows:

I had made two disks-startup, and extras. Startup contained all the files that the mac needs to boot (i.e. system, finder and system enablers), that's all. Extras has all the control panels, extentions, apple menu, and so forth.

My idea was to boot from the startup disk, create a RAM disk of about 2 MB, copy the extras disk in, and reboot from the RAM disk. Yipee! My floppy drive is now free for running programs/saving data!

However, when I went to create a RAM disk, the Memory control panel would only let me set a size of up to 1 MB, which is not even big enough for a basic system folder (my mac has 4MB in total).

Why is this and is there anything I can do about it :?: ?

P.S. The hard drive works occasionally, so feel free to suggest things which would need that to create, but not use (i.e. if I need to boot from the hard disk for some setup thing, that's fine, but I can't always run from it).

 

spiceyokooko

Well-known member
My idea was to boot from the startup disk, create a RAM disk of about 2 MB, copy the extras disk in, and reboot from the RAM disk. Yipee! My floppy drive is now free for running programs/saving data!
Well that isn't going to work given that Macintosh clears the RAM disk at shut down.

Why is this and is there anything I can do about it
This information isn't that hard to find if you make an effort to find it -

http://support.apple.com/kb/TA21561?viewlocale=en_US

http://support.apple.com/kb/TA21631?viewlocale=en_US

The hard drive works occasionally
You know the reason the hard disk doesn't work properly, but you refuse to do anything about it.

 

uniserver

Well-known member
i did this with my powerbook 170, and that cool powerbook 170 (6.0. 8) boot disk,

maybe its because its a laptop or because its a soft power design, but i could set the ram disk for 8meg's

copy 7.5.5 over and it boot even after a shut down.

this was very helpful to me because, it has has a bad hard drive, and because the battery still holds about an hour charge, it works great for my son to play with!

The Quadra q605, LC 475 does not have soft power setup, i have a Mac IIsi, i am going to try later tonight to see if it keeps the ram disk after a shut down.

 

register

Well-known member
Most likely the PB 170 is not able to boot from a RAM disk without the help of some storage device that holds the RAM disk contents as long as the computer is off. Also it always will need a helper disk to cold boot a system up to a point to make a RAM disk operational (i.e. boot from a System floppy and copy a backup into RAM from a non volatile storage device, like internal harddisk drive, as the RAM content is lost each time the computer is powered off).

However, suspending to sleep mode and waking up again should work well with a PowerBook using a RAM disk. A P475 could be equipped with up to 132 MB of RAM, which is enough to hold a RAM disk as large as the stock harddisk drive plus leaving enough RAM for the system to work. There was some shareware available for System 7.1 to automate the task of backing up und restoring the RAM disk contents to harddisk (look for something like ramBunctious). With enough RAM you could conveniently take advantage of a large RAM for a nice speed boost regarding file operations.

 

uniserver

Well-known member
with the powerbook 170 when i did a shut down, as long as the battery had some charge or the charger is plugged in, the ram disk stays and will boot.

 

onlyonemac

Well-known member
My idea was to boot from the startup disk, create a RAM disk of about 2 MB, copy the extras disk in, and reboot from the RAM disk. Yipee! My floppy drive is now free for running programs/saving data!
Well that isn't going to work given that Macintosh clears the RAM disk at shut down.
I am doing a warm restart ("Restart" from the special menu in System 7). It will boot from a RAM disk-I tested it with a little trick. I created a RAM disk and fooled it into blessing it by using one of the System Enablers as "Finder". It blessed and booted, although, of course, returned a finder error bomb.

I didn't think, of course, that my fooling would actually work, but it did show that the mac booted happily :b&w: from a RAM disk. Only trouble is I can't make it big enough. Will check the links posted.

The hard drive works occasionally
You know the reason the hard disk doesn't work properly, but you refuse to do anything about it.
I'm not going to waste my time doing something without knowing if it's going to work. Something which will work 100%-fine, but not wasting money on something which doesn't actually help in the end.

 

spiceyokooko

Well-known member
I'm not going to waste my time doing something without knowing if it's going to work. Something which will work 100%-fine, but not wasting money on something which doesn't actually help in the end.
Then with respect, you probably need to find yourself a new hobby, because fixing these old machines has no guarantees attached to them. A lot of it is trial and error - there are no guarantees anything will work 100%.

However, being slightly, but not hugely philanthropic in nature, I'll offer you a deal.

I can see you're in the UK, like me, so what I'm prepared to do is this. I'll send you FREE of charge a known working (known working because I will have tested it) SCSI hard disk with a preloaded System 7 for your particular machine. If this fixes your problem, in other words it was simply a bad Hard Disk drive, you can keep it for free. If it doesn't fix your problem (as I suspect it won't) you can send it back to me at your own expense. I'll also have a look for some RAM simms that might work in your machine, but no guarantees on that because I haven't looked yet at what I've got or what your machine needs.

Let me know if this is something you're interested in and if you are pm me your address.

 

onlyonemac

Well-known member
I've just made my biggest RAM disk ever (1800K) with the most free RAM ever (over 4000K, more than I have installed in the Mac) :) ! How the heck? Here's how, so you can try it yourself ;) :

1-Download and extract the RAM disk program listed in my previous post.

2-Download and extract the Connectix RAM Doubler installer (don't install anything yet).

3-Get a blank floppy (you need a 1.4 MB one ;) ).

4-Copy your System and Finder files, putting them in a folder called System Folder, across to the floppy (you should bless the folder at this point).

5-Copy your Finder preferances into the new preferances folder on the floppy (if you don't see the folder, then close and reopen the floppy window).

6-Copy the RamDisk+ extension onto the floppy (this one goes straight in the System Folder, not the extensions folder).

7-Run the RAM Doubler installer, choosing to install onto the floppy (you have to do it like this, otherwise you leave a couple of extra hidden things behind :I ).

8-Now for the tricky part. Try copying your System Enabler onto the floppy. It may go fine first time, but if not, then you'll need to shave something off.

9-If needed, you can try reducing the sizes of your System, Finder, and RAM Doubler files until there's enough free space on the floppy (see below).

10-When there's space, copy your System Enabler across to the floppy (if you haven't done so already).

11-Restart your Mac and boot from the floppy (or, if you're like me, shut the emulator down and boot the real Mac from the floppy ;) !).

12-You should have a message from RAM Doubler in the "Welcome to Macintosh" box, but it's OK if the RamDisk icon shows that it's disabled.

13-Wait for the machine to finish booting, then set up the RamDisk extension (see below).

14-Reboot and have fun :cool: !

Shaving down your files:

You can reduce the size of the System, Finder, and RAM Doubler files on your floppy by following these simple instructions. To do this, you'll need a resource editor, such as ResEdit, and a bit of know-how. For the System file, you can delete the PAT# resources (I think that's what they're called), the help images (in the PICT resources) if you don't need them, certain strings from the STR# resources (such as the file sharing messages or balloon help strings if you don't need those), and anything else which you dare to touch. The Finder can be done in the same manner. RAM Doubler may be big enough to fit on your floppy, but I got it down quite a bit by reducing the length of the error messages (STR# resources). It is wise to keep them, because you never know what might go wrong, and it's easier to find the fault if you don't get a pile of blank dialog boxes! But they really don't need to say things like "RAM Doubler has failed to load because it appears that you are using to different versions of RAM Doubler. Please reinstall...". Instead, just say "RAM Doubler could not load: you are using to different versions" ;) . I also once tried removing the PowerPC code resources, but I got an installation error :( .

Configuring RamDisk:

There are a couple of different ways to set this up, depending upon your personal tastes, but there are a couple of essential options :) . You obviously need to start by choosing to use a RAM Disk and selecting to "copy to RAM Disk" (I don't even know why they give you these options ;) ). Then select your files by clicking on the "Selections..." button, and set the RAM Disk parameters by clicking on the "Settings..." button. I think the boxes actually came up automatically when you choose to use the RAM Disk, so this may not be nessecary. But in any case, you need to choose to copy your entire System Folder, but you may leave out the RamDisk and RAM Doubler extensions (I haven't tried that, but I always delete them afterwards anyway, so I don't see why not :) ). The settings are mostly a matter of personal choice, but you need to set the RAM Disk size to be big enough to hold all your files, as well as having a bit of free space (however, for some reason, if you only leave a few kilobytes of free space, it just chops it off :( !). I set mine to 1800K, so I've got over 400K free, and I'm thinking of increasing it more as well! Chances are, however, that it won't let you set it that big using the slider, so you have to type the number into the box (ignore the stupid error it gives you-there's no problem :) ). Finally, back on the main screen, remember to say "switch to RAM disk" and "eject floppies" so that your Mac will actually run from the RAM Disk. Finally, you can choose to show the startup icon if you like to "watch the init progression" (Macintosh Bible quote).

 

onlyonemac

Well-known member
Dear Mods

I thought that I should maybe bring to your attention that perhaps my previous post may be stickied at the top of either the Software forum or the Hacks and Developement forum, such that other users whishing to do this can find it easier. Perhaps something like "How to run from a RAM Disk"?

Thanks in advace, onlyonemac

P.S. Please PM me either way!

 
Top