Cold Hard Cache 3.5
Cold Hard Cache 3.5
for the Atari ST and MEGA ST Computers
with or without a Hard Disk
Copyright 1989, Robert E. Owens III
Cold Hard Cache is an easy to use disk caching program that
works with both hard drives and floppies. Disk caching improves
disk I/O speed by keeping the sectors that are used most
frequently in RAM. The I/O speed of a cached drive will be between
that of a RAM disk (very fast) and the uncached drive (much slower
than a RAM disk).
Benefits:
o Faster disk operation.
o Longer life for your disk drives.
o Longer life for your media.
o Less waiting on programs that grind your disks.
Drawbacks:
o The cache program and the sector buffers take up some
RAM memory (about 20K minimum).
Cold Hard Cache was designed to be as small, reliable, and as
fast as possible. The program buffers reads only. All writes go
directly to disk unless the sector is already in the cache and the
data has not changed. This ensures that the disk's contents are
current in case of a crash, power failure, or accidentally
powering off the computer.
The size of the code may surprise you. Good things come in
small packages. Version 1.0 was about 8K long while Version 3.5 is
just over 2K long. The code has been carefully refined and tested
for about two years on several models of hard drives including
Atari, Supra, and ICD models and should be compatible with any
other models.
Included Files:
cachev3.prg The caching program.
chcstat.prg The GEM application status/configuration
program.
chcstat.acc The GEM accessory status/configuration
program.
chcstat.rsc The GEM resource file for both chcstat.prg and
chcstat.acc.
chcache.doc This file.
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Cold Hard Cache 3.5
Installation:
1. Place the following files in the root directory of your boot
disk:
chcstat.prg
chcstat.acc
chcstat.rsc
2. Place cachev3.prg in the AUTO folder of your boot disk. Make
sure it is placed after your hard disk driver (like AHDI.PRG
on Atari drives). Also, if you are networked, make sure
cachev3.prg is placed BEFORE your network driver or there is
a very good chance of scrambled files.
Configuration/Status Reporting:
General:
There are two versions of the configuration/status program.
Chcstat.prg and Chcstat.acc. They both operate the same except one
is a stand-alone program and the other is a desk accessory. I will
refer to these as the Chcstat from here on.
Chcstat first tests whether cachev3.prg is installed. If it
is not Chcstat will complain. Then a dialog is displayed.
The top half of the dialog contains performance and status
info. The bottom half contains configuration settings.
Configuration:
You may choose the size of the cache and the drives you wish
to be cached. The size of the cache is measured in buffers. Each
buffer requires 524 bytes (512 for the sector, 12 overhead). The
cache should be at least 32 buffers but not too big. I usually use
256 buffers (about 128K). You can try various sized caches and
watch the statistics to find a good size.
You may choose the maximum sized multi-sector transfer to be
considered cachable. The default setting is 4 (512 bytes *
4 sectors = 2K). You may specify any value from 1 to 9999 sectors.
Large values will cause a loss of performance since large
transfers (like program loads) will fill the cache and flush
potentially useful sectors (like directory and FAT sectors). You
may tune the cache for your particular needs. If you use a
database with large records you may wish to specify a larger max
size to accomodate the size of your records.
You may also choose the drives you wish to be cached. Select
the drives with the mouse. Caching is enabled on the Selected
drive letters. There is no harm if you enable a drive that doesn't
exist. If you enable caching on a ramdisk you will make it work
SLOWER than if it was not cached.
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Cold Hard Cache 3.5
Status/Performance:
The status and performance info is useful for tuning the size
of the cache for optimum performance for your hardware/software
environment. The performance is based on cachable sectors.
An average access time is given (in milliseconds) which
represents the average time it takes to locate and read a cachable
sector from disk. The average is for all of the enabled drives,
not just one drive.
The approximate read time is displayed which represents the
total amount of time it took to read all of the cachable sectors.
The approximate time savings is calculated from the average
access time and the number of sector requests satisfied from the
cache (Hits).
The read status shows the number for cachable sector requests
(tries), the number of those requests satisfied from the cache
(hits), and the percentage of hits.
The number of write optimizations is displayed. A write
optimization occurs when a sector write is requested and the
sector is in the cache AND the contents of the sector does not
change so no write takes place.
Exiting:
There are three ways of exiting the dialog.
Cancel The Cancel button will exit without changing any of
the settings.
OK The OK button will enable the selected drives and
then exit. Any changes to the size will be ignored.
If the Reset Stats button is selected the
statistics will be reset.
Save The Save button will save the current settings in
the cache.inf file (so they will take effect after
the next boot), enable the selected drives and then
exit. If the Reset Stats button is selected the
statistics will be reset.
NOTE: The cache program cachev3.prg must be positioned in the
AUTO folder after your hard disk driver (ahdi.prg for
Atari drives) and before any network drivers.
NOTE: If the alternate key is held down when cachev3.prg is
run (from the \auto folder during the boot process) the
cache will NOT be installed.
NOTE: Users of TURBODOS may see lower performance since
TURBODOS does some caching internally. TURBODOS will
disable caching on floppies since it bypasses RWABS()
and the ROM routines that handle floppies. Cachev3 when
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Cold Hard Cache 3.5
used with TURBODOS can still give good results if there
is lots of disk activity. Try it and see what you get.
NOTE: Cachev3 should work with TOS 1.4 with Extended
partitions (> 16 Meg) however only the first 16 Meg will
be cachable. THIS HAS NOT BEEN TESTED! TRY IT AT YOUR
OWN RISK! MAKE SURE YOU HAVE A BACKUP OF YOUR DRIVE
BEFORE YOU TRY!
NOTE: Cachev3 prevents writes to the boot sector (# 0) for
enabled drives. This will prevent utilities that make
partitions bootable (or viruses) from working.
NOTE: Some Hard Disk utilities (like markbad) will not
function correctly when the caching is enabled. Simply
disable the drives with the chcstat program or
accessory.
BUG ALERT:
Cold Hard Cache 3.2 did NOT recognize Media Changes
correctly. This may have affected Removable Hard Drives as
well as Floppies. This has been corrected in version 3.3.
Cold Hard Cache 3.3 would crash (Address error) if a read or
write request specified a transfer to or from an odd address
(very rare). This has been corrected in version 3.4.
Cold Hard Cache versions before 3.5 would not allow floppies
to format correctly. Writes to the Boot Sector were not
permitted. They are now allowed for floppies but NOT allowed
for drives C through P.
Cold Hard Cache was written using the Mark Williams C
Compiler. I highly recommend this product.
Cold Hard Cache is released as Shareware.
If you use this program please make a donation ($15 or so)
to:
Robert E. Owens III
34 Pinecrest Dr.
Covington, LA 70433
USA
This program was designed to save time and has proved to be
valuable. I usually save 20 to 40 minutes a day!
If you have any suggestions or comments about this program I
would like to here from you. I can be reached by Stamp Net (at the
above address) or on Genie (at R.OWENS3).
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