(Moved from the "I JUST GOT THIS" thread.) 
Continuing on the discussion
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OK, I tried it with 3.1 again, and it didn't work. So it might like 2.0, but not 3.1.
It says it patches the trackdisk. If that changed significantly, I can see that causing problems? Especially if their executable is looking for certain things to patch..
Might it be possible (probably not for me, but) to compare the trackdisk before/after that patch and figure out what would need to be patched into the 3.1 trackdisk??
I'm not at all familiar with patching these drivers, so... :huh:
Also interesting about them trying to get to to read IBM HD disks and failing apparently (not being able to slow it to half speed)...
Thanx for the info!!
desiv
Continuing on the discussion
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Not really! :smile:
I found a review of it on the AW December 90 issue. It will shed some light to most o your questions, and i hope it is alright for me to post it here. If not, the mods can take it elsewhere.. So, here goes:
AEHD Drive
More mileage from a drive
By Sheldon Leemon
EXTERNAL FLOPPY-DISK drives are among the most popular of Amiga peripherals, and yet you'll rarely see a review of one. That's because for the last Five years, such drives have all been pretty much alike. Some have offered a pass-through connector to let you hook up additional drives, some a power switch or a design that eliminates the usual clicking sound that occurs when the drive is empty.
Their main function, however—reading and writing standard 880K. Amiga
format disks—has remained unchanged. While other computer systems have
switched to high-density, 3.5-inch floppies having double the capacity of standard models, the Amiga has been plugging along with its original drive,
leaving frustrated owners to ask themselves, "If we can put a man on the moon, why can't we put a high-density floppy in an Amiga?"
Through Apple-Colored Glasses
The first company to provide some kind of answer to this question is Applied Engineering, a company best known for its Apple II peripherals. The Apple connection is apparent in the styling of the AEHD high-density drive for the Amiga.
It looks identical to the Macintosh version of the drive, right down to the Mac-platinum color. In fact, the company has not even changed the packaging, which identifies the drive as an 800K unit ''compatible with all Macintosh Series,
Apple IIGS, IIC Plus, lie," and bears an endorsement from Sieve Wozniak, cofounder
of Apple. (I always figured the Woz was an Amiga fan at heart.)
Applied Engineering's origins seem to have given the company a different perspective on the Amiga market. This drive differs in several respects from the standard Amiga unit. It's got a stylish plastic case (as opposed to the bent metal case of most inexpensive Amiga drives). It features a dual-color activity LED that
glows green when the drive is reading, and red when it is writing—which, if
nothing else, tells when the drive is working instead of just hung up.
More important, it features an electronic drive-eject system rather than a
mechanical one. The eject button is actually a soft-touch switch that sends an
electronic request to the drive, asking it to eject the disk. If the drive is busy
when you press the button, the unit politely ignores your request until disk activity is safely finished. This completely eliminates the possibility of ejecting a
disk before a write operation has been completed, an action that often results in
the dreaded "Volume VitalWork: has a Read/Write Error" message.
Although electronic ejection is easier and safer, it works only when the drive is
connected to the computer and the computer is turned on. When the power is off,
you must use the back-up mechanical eject system, which involves pushing the
end of paper clip into a small hole on the front of the drive.
Data Demon
The AEHD's most significant feature is its ability to store over 1,5MB of information on a single high-density floppy. This capability is not automatic; to take
advantage of it, you must install a device driver (which patches the normal trackdisk.device) and add the device to the system using the MOUNT command.
The drive comes with detailed instructions for installing the needed software,
as well as an installation script that takes care of it automatically. This script does
not alter your startup-sequence file so that it automatically mounts the highdensity
drive, but this is a fairly simple task to accomplish for anyone familiar
with text-file editing. The driver software does work on a 3000 under 2.0.
Once mounted and installed, the AEHD drive acts as two drives. When
you insert a standard-density floppy, the computer recognizes the drive by its
usual AmigaDOS designation (df1: for the first external drive on a 500, df2: for the first external drive on a 2000).
If, however, you insert a high-density disk (these have an extra square hole opposite the write-protect hole and the letters "HD" printed by the shutter), the system recognizes the drive by the name under which you mounted the high-density device (usually df5: for the first external drive on a 500 and df6: for the first on a 2000).
Applied Engineering handles more data by simply slowing the drive's disk-rotation
speed. Originally, the company had planned to double the normal disk capacity to 1.76 megabytes by slowing the drive to half speed, but this did not work. The final version stores only 19 sectors per track instead of 22, for a total
of 1.52MB per disk. As a result, the drive is unable to read 1.4-4-meg, IBMformat
disks as originally advertised (though it can read a 720K MS-DOS disk, with the help of a format-conversion utility such as Consultron's Cross DOS).
The Arithmetic of Reading and Writing
As you might expect, slowing down the drive affects the speed at which it reads
and writes data. Using the Diskspeed program to measure it, I found that the high-density drive writes at just 525 bytes per second, instead of the usual
3000 bytes per second. In actual practice, however, writing files to the high density
disk turned out to be onlv about 20-25% slower than writing them to a standard floppy.
On the other hand, disk reads were consistently 20-25% faster in the high density
mode. This means that under normal conditions, in which you read from disks much more frequently than you write to them, the high-density mode should be faster than standard mode. You will probably find that high-density mode makes the process of backing up a hard drive a little faster than usual because of
the reduction in floppy swaps.
As with most new products, the AEHD drives had some bugs to shake out. The
first unit i tested worked unreliably (due to production problems in the initial run), and the original manual had numerous typographic errors. The second unit worked flawlessly, however, and came with a corrected manual. All told, I was quite impressed. While the AEHD does not offer double the storage, it does provide more capacity than comparable IBM drives. And even in normal-density mode, the electronic-eject button is an important safeguard. Most important, however, the AEHD Drive represents a much-needed step away from the status quo, paving the way for new generations of improved floppy drives on the Amiga.
Hope you make something out of it, plus it has some very interesting facts for people tinkering with floppies in general
My understanding is that it isn't 1.x exclusive! :smile:
OK, I tried it with 3.1 again, and it didn't work. So it might like 2.0, but not 3.1.
It says it patches the trackdisk. If that changed significantly, I can see that causing problems? Especially if their executable is looking for certain things to patch..
Might it be possible (probably not for me, but) to compare the trackdisk before/after that patch and figure out what would need to be patched into the 3.1 trackdisk??
I'm not at all familiar with patching these drivers, so... :huh:
Also interesting about them trying to get to to read IBM HD disks and failing apparently (not being able to slow it to half speed)...
Thanx for the info!!
desiv
