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----------------------------------------------------------------------------
STAT-RAM 2.1
----------------------------------------------------------------------------
A joint effort by
Richard Waspe
INTERNET : waspy@cix.compulink.co.uk
USENET : rwaspe@hamlet.adsp.sub.org
FIDONET : 2:255/72.2
Nicola Salmoria
INTERNET : MC6489@mclink.it
StatRam is a very fast, very recoverable ram drive. It works on any
Amiga using V2.04 or greater of the OS. It maintains the remarkable
recoverability of the original VD0:, but has now been totally
re-written to handle any DOS filesystem, be named what you like, and
give back memory from deleted files instantly. Please follow these
instructions closely as the setup is very different from earlier
versions of StatRam.
The files in this archive are based on asdg.vdisk.device, originally
** Copyright 1987 By Perry S. Kivolowitz (ASDG Incorporated) All Rights
** Reserved to Author. NOT IN THE PUBLIC DOMAIN.
We are not willing to infringe copyright laws; but since there hasn't been
any update in the last five years, we are trying to provide an useful tool
to the Amiga community. StatRam 2 has been so totally re-written,
there is almost none of the original remaining. However, the same
distribution restrictions of the original apply:
** May not be distributed by any commercial software or hardware vendor.
** May not be sold under any guise.
** Must (please) contain this and copyright information above and below.
**
** Specifically:
**
** No maker or seller of Amiga expansion hardware or software may dis-
** tribute this software in *any* way. No reseller of public domain
** software may distribute this software either (as this is *NOT* in the
** public domain).
**
** The only acceptable means of distribution is by networks, bbs's, fnf,
** and by (non-profit) user groups. Distribution MUST BE FREE (except for
** media costs plus a token amount covering only shipping and handling).
Overview
--------
Some of you will remember, and maybe still use, one of the first
recoverable ram disks ever written for the Amiga: VD0.
VD0 is quite good at its job, and is probably the one which resists the
heaviest system crashes. It also uses memory in a very efficient way,
starting from the bottom of the memory pool and thus avoiding
fragmentation. This also means that if you have both 32-bit (fast!) and
16-bit (slow!) memory, it will use 16-bit memory first, leaving the faster
memory for more important tasks.
Unfortunately, VD0 also shows its age. It doesn't support FastFileSystem,
and it doesn't work on machines which don't have fast memory in 24-bit
addressing space.
Here is the solution. We have completely disassembled asdg.vdisk.device,
and made major changes and enhancements in it. The result is a new device
called static.device, which holds the advantages of VD0 and enhances them
with new features. Static.device:
- Supports all filesystems from OFS to the new DCFS provided with OS 3.0.
- Works on all machines. At least, we hope so.
- Frees unused memory almost instantly..
- May be named anyway you like - it's not stuck to SD0:
- Will test sector checksums on every read (_very_ important with Fast
File System which doesn't do it by itself).
Installation
------------
- Copy static.device to DEVS:
- If you have Workbench 2.1 or later, drag the icon SD0 to DEVS:DOSDrivers.
If you have Workbench 2.04, join the file named Mountlist to
DEVS:Mountlist, and add a 'Mount SD0:' command to your user-startup.
Otherwise, you're in bad luck: it won't work with previous releases of
the operating system.
Configuration
-------------
You may control three aspects of SD0:
- Its size
- The type of memory it uses
- The filesystem it uses
These changes are performed modifying some parameters in the mount
information.
If you are using Workbench 2.04, you have to edit DEVS:Mountlist by hand;
otherwise, modify the ToolTypes in the DEVS:DOSDrivers/SD0 icon.
Modifiable parameters are:
HIGHCYL
This one determines the _maximum_ size of SD0. The device will
dinamically allocate memory only when it's needed, growing and shrinking
as you copy and delete files in it.
SD0 uses tracks of 16 512 bytes sectors, that is 8k per track.
The total size in kilobytes therefore (HighCyl+1)*8.
Suggested HighCyl values are:
Fast Ram Installed HighCyl Value Max Ram Disk Size
0 15 128K
512Kbyte 31 256K
1Mbyte 63-95 512K-768K
2Mbytes 127-191 1Mbyte-1.5Mbytes
4Mbytes 255-383 2Mbytes-3Mbytes
8Mbytes 511-767 4Mbytes-6Mbytes
**** This value MUST be odd! ****
The maximum allowed value is 1023; however remember that it is _much_
better to fill the disk than to run out of memory. So, make sure that
you don't set HighCyl too high.
BUFMEMTYPE
If you have some fast memory, leave this set to 5.
If you only have chip memory, set it to 3.
DOSTYPE
This tells the system which file system to use. Possible values are:
0x444F5300 Old File System
0x444F5301 Fast File System
0x444F5302 Old File System International
0x444F5303 Fast File System International
0x444F5304 Old File System - Directory Cache (OS 3.0 only)
0x444F5305 Fast File System - Directory Cache (OS 3.0 only)
You will most probably leave this field to its default value.
Note that there is really no point in using the Directory Cache file
systems on a ram disk - they will actually slow it down.
Other Utilities
---------------
The command 'KillSD0' is used to clear the contents of the ram disk.
Note that the disk will not be erased immediately, but only the next time
you reset.
Hints and Tips
--------------
Many people like to completely replace the standard RAM: volume with the
recoverable ram disk. This can be easily done by changing the name of the
mount entry from SD0 to RAM, and adding the following lines at the
beginning of the startup-sequence, before any reference to RAM: (but after
SetPatch):
Assign ENV: SYS:
Assign RAM: DISMOUNT
Mount RAM:
Revision History
----------------
2.1 (25.6.93)
- Wasn't surviving resets on machines with memory at $C00000 (aka Ranger
Memory). Now, Ranger Memory is never used. This means that on 1M machines
only Chip Memory is available for the ram disk.
- Added the Hints and Tips section to the docs.