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+NOTES ON RADIOTRACK CARD CONTROL
+by Stephen M. Benoit (benoits@servicepro.com)  Dec 14, 1996
+----------------------------------------------------------------------------
+
+Document version 1.0
+
+ACKNOWLEDGMENTS
+----------------
+This document was made based on 'C' code for Linux from Gideon le Grange
+(legrang@active.co.za or legrang@cs.sun.ac.za) in 1994, and elaborations from
+Frans Brinkman (brinkman@esd.nl) in 1996.  The results reported here are from
+experiments that the author performed on his own setup, so your mileage may
+vary... I make no guarantees, claims or warranties to the suitability or
+validity of this information.  No other documentation on the AIMS
+Lab (http://www.aimslab.com/) RadioTrack card was made available to the
+author.  This document is offered in the hopes that it might help users who
+want to use the RadioTrack card in an environment other than MS Windows.
+
+WHY THIS DOCUMENT?
+------------------
+I have a RadioTrack card from back when I ran an MS-Windows platform.  After
+converting to Linux, I found Gideon le Grange's command-line software for
+running the card, and found that it was good!  Frans Brinkman made a
+comfortable X-windows interface, and added a scanning feature.  For hack
+value, I wanted to see if the tuner could be tuned beyond the usual FM radio
+broadcast band, so I could pick up the audio carriers from North American
+broadcast TV channels, situated just below and above the 87.0-109.0 MHz range.
+I did not get much success, but I learned about programming ioports under
+Linux and gained some insights about the hardware design used for the card.
+
+So, without further delay, here are the details.
+
+
+PHYSICAL DESCRIPTION
+--------------------
+The RadioTrack card is an ISA 8-bit FM radio card.  The radio frequency (RF)
+input is simply an antenna lead, and the output is a power audio signal
+available through a miniature phone plug.  Its RF frequencies of operation are
+more or less limited from 87.0 to 109.0 MHz (the commercial FM broadcast
+band).  Although the registers can be programmed to request frequencies beyond
+these limits, experiments did not give promising results.  The variable
+frequency oscillator (VFO) that demodulates the intermediate frequency (IF)
+signal probably has a small range of useful frequencies, and wraps around or
+gets clipped beyond the limits mentioned above.
+
+
+CONTROLLING THE CARD WITH IOPORT
+--------------------------------
+The RadioTrack (base) ioport is configurable for 0x30c or 0x20c.  Only one
+ioport seems to be involved.  The ioport decoding circuitry must be pretty
+simple, as individual ioport bits are directly matched to specific functions
+(or blocks) of the radio card.  This way, many functions can be changed in
+parallel with one write to the ioport.  The only feedback available through
+the ioports appears to be the "Stereo Detect" bit.
+
+The bits of the ioport are arranged as follows:
+
+  MSb                                                         LSb
++------+------+------+--------+--------+-------+---------+--------+
+| VolA | VolB | ???? | Stereo | Radio  | TuneA | TuneB   | Tune   |
+|  (+) |  (-) |      | Detect | Audio  | (bit) | (latch) | Update |
+|      |      |      | Enable | Enable |       |         | Enable |
++------+------+------+--------+--------+-------+---------+--------+
+
+
+VolA . VolB  [AB......]
+-----------
+0 0 : audio mute
+0 1 : volume +    (some delay required)
+1 0 : volume -    (some delay required)
+1 1 : stay at present volume
+
+Stereo Detect Enable [...S....]
+--------------------
+0 : No Detect
+1 : Detect
+
+  Results available by reading ioport >60 msec after last port write.
+  0xff ==> no stereo detected,  0xfd ==> stereo detected.
+
+Radio to Audio (path) Enable [....R...]
+----------------------------
+0 : Disable path (silence)
+1 : Enable path  (audio produced)
+
+TuneA . TuneB [.....AB.]
+-------------
+0 0 : "zero" bit phase 1
+0 1 : "zero" bit phase 2
+
+1 0 : "one" bit phase 1
+1 1 : "one" bit phase 2
+
+  24-bit code, where bits = (freq*40) + 10486188.
+  The Most Significant 11 bits must be 1010 xxxx 0x0 to be valid.
+  The bits are shifted in LSb first.
+
+Tune Update Enable [.......T]
+------------------
+0 : Tuner held constant
+1 : Tuner updating in progress
+
+
+PROGRAMMING EXAMPLES
+--------------------
+Default:        BASE <-- 0xc8  (current volume, no stereo detect,
+                                radio enable, tuner adjust disable)
+
+Card Off:       BASE <-- 0x00  (audio mute, no stereo detect,
+                                radio disable, tuner adjust disable)
+
+Card On:        BASE <-- 0x00  (see "Card Off", clears any unfinished business)
+                BASE <-- 0xc8  (see "Default")
+
+Volume Down:    BASE <-- 0x48  (volume down, no stereo detect,
+                                radio enable, tuner adjust disable)
+                * wait 10 msec *
+                BASE <-- 0xc8  (see "Default")
+
+Volume Up:      BASE <-- 0x88  (volume up, no stereo detect,
+                                radio enable, tuner adjust disable)
+                * wait 10 msec *
+                BASE <-- 0xc8  (see "Default")
+
+Check Stereo:   BASE <-- 0xd8  (current volume, stereo detect,
+                                radio enable, tuner adjust disable)
+                * wait 100 msec *
+                x <-- BASE     (read ioport)
+                BASE <-- 0xc8  (see "Default")
+
+                x=0xff ==> "not stereo", x=0xfd ==> "stereo detected"
+
+Set Frequency:  code = (freq*40) + 10486188
+                foreach of the 24 bits in code,
+                (from Least to Most Significant):
+                  to write a "zero" bit,
+                    BASE <-- 0x01  (audio mute, no stereo detect, radio
+                                    disable, "zero" bit phase 1, tuner adjust)
+                    BASE <-- 0x03  (audio mute, no stereo detect, radio
+                                    disable, "zero" bit phase 2, tuner adjust)
+                  to write a "one" bit,
+                    BASE <-- 0x05  (audio mute, no stereo detect, radio
+                                    disable, "one" bit phase 1, tuner adjust)
+                    BASE <-- 0x07  (audio mute, no stereo detect, radio
+                                    disable, "one" bit phase 2, tuner adjust)
+
+----------------------------------------------------------------------------