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Panorama - Disk 28C (1988-04-27)(Pacific North-West Amigas Club)[WB].zip
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A2000.Janus.speed.txt
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1988-03-26
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Amiga 2000 Bridge Card Hard Drive Performance
These are the results of some interleave adjustment experimenting I
did on my Amiga 2000. I found that the proper adjustment can make a
BIG DIFFERENCE in hard drive performance. Pleading ignorance and
just accepting the defaults are a good way to insure sub-standard
performance.
My particular setup is as follows:
Amiga 2000 equiped with bridge card.
Western Digital hard drive controller
Miniscribe 8438 32meg hard disk drive (mini 3 1/2 inch
mounted inside Amiga in second drive bay.
By adjusting the interleave value I was able to increase my data
transfer rate by 567%. That's nearly a six to one increase!
Interleave | Revolutions | Tranfer Rate | Comments
Value | Per Cylinder | In Bytes |
------------------------------------------------------------------
2 | 18 | 29,002 | Unusually long low
| | | level format time
3 | 18 | 29,002 |
| | |
4 | 17 | 30,317 | Default in format setup
| | |
5 | 3 | 174,080 | Optimum for my setup
| | |
6 | 4 | 130,560 |
| | |
7 | 5 | 104,448 |
| | |
8 | 5 | 104,448 |
As can be noted in the chart above too tight an interleave (small
value) can cause far worse performance than too loose (large value).
The results can be anticipated because most PC/XT running at 4.77mhz
should be have their hard drive formated at an interleave of 5. Only
8mhz PCs usually are formated at 4. This is only in general as the
particular system as a whole (computer, controller & drive) affects
the outcome. Only by experimenting can the exact value be known for
sure but a little too loose is a lot better than a little too tight.
If in doubt set it looser (larger interleave value). An interleave of
6 should be good for all but the strangest of setup.
In the IBM PC Hardware SIG Disk data library are several programs to
assist in finding the proper adjustment. Beware of programs however
that optimise the interleave for you. I have found none that work
with a bridge card).
The interleave settings for SCSI controllers are just as critical
as I have found when working with UNIX workstations. Presently I do
not have a SCSI drive in my setup but I would hope by the time I do
some programs such as I found in PC SIG would exist for the Amiga. I
am somewhat doubtful that the manufacturers can be counted on to
insure maximum performance. This is especially true considering some
of the more unique systems that can be made with an Amiga (68020-30
at greater than standard speeds).
Mark A. Raschke
Compuserve - 72416,2511
GEnie - M.A.Raschke