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+=======================================================
+Documentation for the NeoMagic 256AV/256ZX sound driver
+=======================================================
+
+You're looking at version 1.1 of the driver.  (Woohoo!) It has been
+successfully tested against the following laptop models:
+
+        Sony Z505S/Z505SX/Z505DX/Z505RX
+        Sony F150, F160, F180, F250, F270, F280, PCG-F26
+        Dell Latitude CPi, CPt (various submodels)
+
+There are a few caveats, which is why you should read the entirety of
+this document first.
+
+This driver was developed without any support or assistance from
+NeoMagic.  There is no warranty, expressed, implied, or otherwise.  It
+is free software in the public domain; feel free to use it, sell it,
+give it to your best friends, even claim that you wrote it (but why?!)
+but don't go whining to me, NeoMagic, Sony, Dell, or anyone else
+when it blows up your computer.
+
+Version 1.1 contains a change to try and detect non-AC97 versions of
+the hardware, and not install itself appropriately.  It should also
+reinitialize the hardware on an APM resume event, assuming that APM
+was configured into your kernel.
+
+============
+Installation
+============
+
+Enable the sound drivers, the OSS sound drivers, and then the NM256
+driver.  The NM256 driver *must* be configured as a module (it won't
+give you any other choice).
+
+Next, do the usual "make modules" and "make modules_install".
+Finally, insmod the soundcore, sound and nm256 modules.
+
+When the nm256 driver module is loaded, you should see a couple of
+confirmation messages in the kernel logfile indicating that it found
+the device (the device does *not* use any I/O ports or DMA channels).
+Now try playing a wav file, futz with the CD-ROM if you have one, etc.
+
+The NM256 is entirely a PCI-based device, and all the necessary
+information is automatically obtained from the card.  It can only be
+configured as a module in a vain attempt to prevent people from
+hurting themselves.  It works correctly if it shares an IRQ with
+another device (it normally shares IRQ 9 with the builtin eepro100
+ethernet on the Sony Z505 laptops). 
+
+It does not run the card in any sort of compatibility mode. It will
+not work on laptops that have the SB16-compatible, AD1848-compatible
+or CS4232-compatible codec/mixer; you will want to use the appropriate
+compatible OSS driver with these chipsets.  I cannot provide any
+assistance with machines using the SB16, AD1848 or CS4232 compatible
+versions.  (The driver now attempts to detect the mixer version, and
+will refuse to load if it believes the hardware is not
+AC97-compatible.)
+
+The sound support is very basic, but it does include simultaneous
+playback and record capability.  The mixer support is also quite
+simple, although this is in keeping with the rather limited
+functionality of the chipset.
+
+There is no hardware synthesizer available, as the Losedows OPL-3 and
+MIDI support is done via hardware emulation.
+
+Only three recording devices are available on the Sony: the
+microphone, the CD-ROM input, and the volume device (which corresponds
+to the stereo output).  (Other devices may be available on other
+models of laptops.)  The Z505 series does not have a builtin CD-ROM,
+so of course the CD-ROM input doesn't work.  It does work on laptops
+with a builtin CD-ROM drive.
+
+The mixer device does not appear to have any tone controls, at least
+on the Z505 series.  The mixer module checks for tone controls in the
+AC97 mixer, and will enable them if they are available.
+
+==============
+Known problems
+==============
+
+  * There are known problems with PCMCIA cards and the eepro100 ethernet 
+    driver on the Z505S/Z505SX/Z505DX.  Keep reading.
+
+  * There are also potential problems with using a virtual X display, and
+    also problems loading the module after the X server has been started. 
+    Keep reading.
+
+  * The volume control isn't anywhere near linear.  Sorry.  This will be
+    fixed eventually, when I get sufficiently annoyed with it.  (I doubt
+    it will ever be fixed now, since I've never gotten sufficiently
+    annoyed with it and nobody else seems to care.)
+
+  * There are reports that the CD-ROM volume is very low.  Since I do not
+    have a CD-ROM equipped laptop, I cannot test this (it's kinda hard to
+    do remotely).
+
+  * Only 8 fixed-rate speeds are supported.  This is mainly a chipset
+    limitation.  It may be possible to support other speeds in the future.
+
+  * There is no support for the telephone mixer/codec.  There is support
+    for a phonein/phoneout device in the mixer driver;  whether or not 
+    it does anything is anyone's guess.  (Reports on this would be
+    appreciated.  You'll have to figure out how to get the phone to
+    go off-hook before it'll work, tho.)
+
+  * This driver was not written with any cooperation or support from
+    NeoMagic.  If you have any questions about this, see their website
+    for their official stance on supporting open source drivers.
+
+============
+Video memory
+============
+
+The NeoMagic sound engine uses a portion of the display memory to hold
+the sound buffer.  (Crazy, eh?)  The NeoMagic video BIOS sets up a
+special pointer at the top of video RAM to indicate where the top of
+the audio buffer should be placed.
+
+At the present time XFree86 is apparently not aware of this.  It will
+thus write over either the pointer or the sound buffer with abandon.
+(Accelerated-X seems to do a better job here.)
+
+This implies a few things:
+
+  * Sometimes the NM256 driver has to guess at where the buffer 
+    should be placed, especially if the module is loaded after the
+    X server is started.  It's usually correct, but it will consistently
+    fail on the Sony F250.
+
+  * Virtual screens greater than 1024x768x16 under XFree86 are
+    problematic on laptops with only 2.5MB of screen RAM. This
+    includes all of the 256AV-equipped laptops.  (Virtual displays
+    may or may not work on the 256ZX, which has at least 4MB of
+    video RAM.)
+
+If you start having problems with random noise being output either
+constantly (this is the usual symptom on the F250), or when windows
+are moved around (this is the usual symptom when using a virtual
+screen), the best fix is to
+
+  * Don't use a virtual frame buffer.
+  * Make sure you load the NM256 module before the X server is
+    started.
+
+On the F250, it is possible to force the driver to load properly even
+after the XFree86 server is started by doing:
+
+        insmod nm256 buffertop=0x25a800
+
+This forces the audio buffers to the correct offset in screen RAM.
+
+One user has reported a similar problem on the Sony F270, although
+others apparently aren't seeing any problems.  His suggested command
+is
+
+        insmod nm256 buffertop=0x272800
+
+=================
+Official WWW site
+=================
+
+The official site for the NM256 driver is:
+
+        http://www.uglx.org/sony.html
+
+You should always be able to get the latest version of the driver there,
+and the driver will be supported for the foreseeable future.
+
+==============
+Z505RX and IDE
+==============
+
+There appears to be a problem with the IDE chipset on the Z505RX; one
+of the symptoms is that sound playback periodically hangs (when the
+disk is accessed).  The user reporting the problem also reported that
+enabling all of the IDE chipset workarounds in the kernel solved the
+problem, tho obviously only one of them should be needed--if someone
+can give me more details I would appreciate it.
+
+==============================
+Z505S/Z505SX on-board Ethernet
+==============================
+
+If you're using the on-board Ethernet Pro/100 ethernet support on the Z505
+series, I strongly encourage you to download the latest eepro100 driver from
+Donald Becker's site:
+
+        ftp://cesdis.gsfc.nasa.gov/pub/linux/drivers/test/eepro100.c
+
+There was a reported problem on the Z505SX that if the ethernet
+interface is disabled and reenabled while the sound driver is loaded,
+the machine would lock up.  I have included a workaround that is
+working satisfactorily.  However, you may occasionally see a message
+about "Releasing interrupts, over 1000 bad interrupts" which indicates
+that the workaround is doing its job.
+
+==================================
+PCMCIA and the Z505S/Z505SX/Z505DX
+==================================
+
+There is also a known problem with the Sony Z505S and Z505SX hanging
+if a PCMCIA card is inserted while the ethernet driver is loaded, or
+in some cases if the laptop is suspended.  This is caused by tons of
+spurious IRQ 9s, probably generated from the PCMCIA or ACPI bridges.
+
+There is currently no fix for the problem that works in every case.
+The only known workarounds are to disable the ethernet interface
+before inserting or removing a PCMCIA card, or with some cards
+disabling the PCMCIA card before ejecting it will also help the
+problem with the laptop hanging when the card is ejected.
+
+One user has reported that setting the tcic's cs_irq to some value
+other than 9 (like 11) fixed the problem.  This doesn't work on my
+Z505S, however--changing the value causes the cardmgr to stop seeing
+card insertions and removals, cards don't seem to work correctly, and
+I still get hangs if a card is inserted when the kernel is booted.
+
+Using the latest ethernet driver and pcmcia package allows me to
+insert an Adaptec 1480A SlimScsi card without the laptop hanging,
+although I still have to shut down the card before ejecting or
+powering down the laptop.  However, similar experiments with a DE-660
+ethernet card still result in hangs when the card is inserted.  I am
+beginning to think that the interrupts are CardBus-related, since the
+Adaptec card is a CardBus card, and the DE-660 is not; however, I
+don't have any other CardBus cards to test with.
+
+======
+Thanks
+======
+
+First, I want to thank everyone (except NeoMagic of course) for their
+generous support and encouragement.  I'd like to list everyone's name
+here that replied during the development phase, but the list is
+amazingly long.
+
+I will be rather unfair and single out a few people, however:
+
+        Justin Maurer, for being the first random net.person to try it,
+        and for letting me login to his Z505SX to get it working there
+
+        Edi Weitz for trying out several different versions, and giving
+        me a lot of useful feedback
+
+        Greg Rumple for letting me login remotely to get the driver 
+        functional on the 256ZX, for his assistance on tracking
+        down all sorts of random stuff, and for trying out Accel-X
+
+        Zach Brown, for the initial AC97 mixer interface design
+
+        Jeff Garzik, for various helpful suggestions on the AC97
+        interface
+
+        "Mr. Bumpy" for feedback on the Z505RX
+
+        Bill Nottingham, for generous assistance in getting the mixer ID
+        code working
+
+=================
+Previous versions
+=================
+
+Versions prior to 0.3 (aka `noname') had problems with weird artifacts
+in the output and failed to set the recording rate properly.  These
+problems have long since been fixed.
+
+Versions prior to 0.5 had problems with clicks in the output when
+anything other than 16-bit stereo sound was being played, and also had
+periodic clicks when recording.
+
+Version 0.7 first incorporated support for the NM256ZX chipset, which
+is found on some Dell Latitude laptops (the CPt, and apparently
+some CPi models as well).  It also included the generic AC97
+mixer module.
+
+Version 0.75 renamed all the functions and files with slightly more
+generic names.
+
+Note that previous versions of this document claimed that recording was
+8-bit only; it actually has been working for 16-bits all along.