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        DDD Version 1.1     With this program and Dysan Corporation's
                                 "Digital Diagnostic Diskette"tm
                            ($30 for SS and $40 for DS as of 1983...)     
                            
                            You can comprehensively test, verify, and
align the heads of your flexible diskette drive, under your own oper-
ating conditions, without need for expensive oscilloscopes and drive
exercisers, to practically the same precision achievable by the usual
analog methods. Any time you suspect a bug in one of your drives, you
can determine which drive is at fault and what the problem is.
No more expensive shot-in-the-dark trips to the service center; no
more intermittent bugs which won't appear for the serviceman. Takes
the mystery out of flexible diskette systems!!


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System Requirements:
The DDDtm is available for all flexible diskette formats, and works
independently of any operating system.  This program is built around
CP/M and the 1793 floppy disk controller chip, and can be easily 
configured and assembled (with ASM - no macros... ) for most CP/M
systems. The screen displays require an addressable cursor and clear
screen facility from your terminal, but you could display the 
test results without the trick graphics if you don't have these
capabilities. 


Operator Requirements:
You will have to know how to edit and assemble 8080 assembly 
language. Step-by-step instructions for customizing the program
will be published in Dr. Dobb's Journal, probably in December
1983. The code is well-commented and could probably be customized
without the magazine if you must. You will, however, need to know 
some hardware-specific information about your terminal and disk
controller; count on needing the manufacturers' manuals and/or
cribbing the information from your BIOS source. (The disk reads
must bypass CP/M function calls entirely - you have to send raw
commands to the controller, and retrieve the data byte-by-byte.)


Tests Performed:
Radial Alignment - on six different tracks, to within 1/2 milliinch
Positioner Hysteresis -     "   , using any offset up to full width
Head Azimuth - from -42 to +42 minutes
Index Timing - inner and outer tracks
Diskette Centering - three levels of difficulty (tests bearings, clamping)
Spindle Speed - (not a function of the DDD... )
(Many other problems, such as dirty heads, will show themselves during
these tests...  You will want to get familiar with the results of the
different tests while your drives are working, so that you can recognize
the changes caused by new bugs.)


Verification:
DDD11.ASM is a 47K file
CRC (Version 5.0 and previous...)     6E 94
CRC (Version 5.1 and derivatives...)   7B79


Author:         LOREN AMELANG

CIS Email [70110,551]  (I access Snail Mail more often than Email...
                            but if you want to send machine code...)
Box 24, Philo, CA  95466 0024   (Best way to contact me...)


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           Take the mystery out of YOUR flexible disk system !!!
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