Ultra Fast RAM Disk for ATARI 520/1040 ST
Version 1.0
April, 1986
by Charles Smeton
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* *
* This program can be freely distributed *
* (excluding media costs), it is and should *
* remain in the PUBLIC DOMAIN. Any questions *
* should b
* arising from the use of this program. *
* *
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This program sets aside a portion of the ST's memory to
act as an Ultra-Fast Disk Drive. Unlike other RAM Disk
programs that are installed as desk accessories, this
RAM Disk can be installed automatically by placing it
in AUTO folder on boot disk. This save a desk accessory
slot for more useful purposes. The RAM disk can also be
installed by renaming it to a ".TTP" extension and clicking
it from the desktop.
To install the RAM Disk for automatic setup upon booting:
1) Install the RAM Disk icon with drive letter you want
the RAM Disk to be. This is accomplished from the
desktop by clicking Floppy Disk A or B's icon once
(causing it to turn black). Then select "Install Disk
Drive" from the "Options" menu in the Desk Top.
Change the "Drive Identifier" to the drive you want the
RAM Disk to be and the "Icon Label" to "RAM DISK". Then
select the "Install" box. Drag the RAM DISK icon to
where you want it to be on the desk top. Insert your
boot disk in drive A and then select "Save Desktop"
from the "Options" menu. This creates the "DESKTOP.INF"
file on the boot disk.
2) Create a new folder on the boot disk called "AUTO",
then copy the RAMDISK.PRG file into this folder.
3) Using a standard text editor create a file called
"RAMDISK.INF" in the main directory of the boot
disk. This file need only contain the following:
a) the drive letter for the RAM Disk
b) the size of the RAM Disk in Kilobytes.
An example would be:
C200
for drive C, 200K bytes.
The drive letter can be any letter upper or lower
case from "C" through "P". The first letter found in
the file in this range is interpreted as the drive
letter. After the drive letter is determined, then
the first numeric character located starts the drive
size number, this number is determined complete when
any non numeric character is found or the end of the
file is detected. If the no number is found, then
a default RAM Disk size of 100K is assumed. Likewise,
if no drive letter is found, then "D" is assumed as
the drive and 100K bytes as the size. If the file
"RAMDISK.INF" is not found on the boot disk, then
the RAM Disk program will also assume the above
defaults.
Note: If a size less than 50K is given, then 50K
is used as the drive size. If there is not enough
memory available, then the RAM Disk is not
installed by the program.
The RAM Disk contents will survive a resolution change
on a color monitor. Since the DESKTOP.INF file will be
re-loaded after a resolution change, make sure it has the
RAM Disk Drive icon installed. It is a good idea to have
the boot disk in drive A during this time, otherwise you
will need to reinstall RAM disk icon manually.
The RAM Disk data transfer has been optimized for speed.
This should out perform many commercial RAM Disks. Try the
RAM Disk with a slide show to see how fast it is.
The RAM Disk can be initialized manually by double
clicking the program file name or icon from the desktop.
If you rename the program to have a ".TTP" extension,
then the RAM Disk Drive parameters can be entered in the
dialog box just as they would be from the RAMDISK.INF file.
If no parameters are given, then the RAMDISK.INF file is
checked for the valid parameters as described above. If
the command line is entered incorrectly, then the default
parameters are used.
The RAM Disk can be initialized from a Command line
interpreter environment, but it is advisable to use
one of the other methods. The command line can be typed
as follows: RAMDISK D200.
The problem using this method is that the memory used
by the command program is below the RAM Disk and cannot
be released to GEMDOS. The system may lockup or the
RAM Disk contents may be lost if the user tries to exit
back to the desktop. If the user plans to stay in the
command environment, then ther is no problem.
RAM Disk Size specification:
Any size RAM Disk from 50K bytes to 60000 bytes below
the total amount of free memory may be specified. As
stated before attempting to use less than 50K bytes,
gives you a 50K byte minimum RAM Disk. The 60000 byte
saftey margin is to insure that there will be enough
memory for the desktop to operate as well as the minimum
to run a small program. The RAM Disk will not be installed
if you specify an amount above this limit.
Note: On a normal 520ST with TOS in ROM, there is enough
room for a 351K RAM Disk. This will not leave much room
for programs to run, but for copying files/disks it
gives the same memory as a single sided disk. On a 1040ST
or expanded 520ST, RAM Disks up to 700K bytes should be
no problem.
Note: You cannot copy a Floppy Disk to/from a RAM Disk by
dragging the disk icon on top of the other icon. This
is true no matter what size RAM Disk is used. To get around
having to draw a box around all the files in a window and
dragging them to the other window or disk icon (this may
take several iterations), just drag the disk icon into the
open (empty) window of the destination. This will copy
each file from the source to the destination disk.
The RAM Disk size specified is the total number of data
clusters available for storage in the RAM Disk. Where one
cluster = two sectors = 1K bytes. The memory needed for the
boot sector (1 sector), the two copies of the File Allocation
Table (FAT) (2 * 5 sectors) and the directory (7 sectors) is
allocated in addition to the specified size . For some reason,
GEMDOS reserves 2K bytes of the specified RAM Disk size for its
own use. The total memory displayed by a "SHOW INFO" of the RAM
Disk's icon be 2048 bytes less than the RAM Disk size * 1024 bytes.
If the RAM Disk is successfully installed, a message indicating
the Drive and size allocated is displayed. If the RAM Disk can
not be installed, then and Error message is printed and two
console beeps are generated to grab your attention. These message
appear for only a second or two, since the desktop will wipe
them out, but there is plenty of time to view them when the
RAM Disk is installed from the AUTO folder.