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 =====================================
 Amiga Buddha and Catweasel IDE Driver
 =====================================
 
 The Amiga Buddha and Catweasel IDE Driver (part of ide.c) was written by
 Geert Uytterhoeven based on the following specifications:
 
 ------------------------------------------------------------------------
 
 Register map of the Buddha IDE controller and the
 Buddha-part of the Catweasel Zorro-II version
 
 The Autoconfiguration has been implemented just as Commodore
 described  in  their  manuals, no tricks have been used (for
 example leaving some address lines out of the equations...).
 If you want to configure the board yourself (for example let
 a  Linux  kernel  configure the card), look at the Commodore
 Docs.  Reading the nibbles should give this information::
 
   Vendor number: 4626 ($1212)
   product number: 0 (42 for Catweasel Z-II)
   Serial number: 0
   Rom-vector: $1000
 
 The  card  should be a Z-II board, size 64K, not for freemem
 list, Rom-Vektor is valid, no second Autoconfig-board on the
 same card, no space preference, supports "Shutup_forever".
 
 Setting  the  base address should be done in two steps, just
 as  the Amiga Kickstart does:  The lower nibble of the 8-Bit
 address is written to $4a, then the whole Byte is written to
 $48, while it doesn't matter how often you're writing to $4a
 as  long as $48 is not touched.  After $48 has been written,
 the  whole card disappears from $e8 and is mapped to the new
 address just written.  Make sure $4a is written before $48,
 otherwise your chance is only 1:16 to find the board :-).
 
 The local memory-map is even active when mapped to $e8:
 
 ==============  ===========================================
 $0-$7e          Autokonfig-space, see Z-II docs.
 
 $80-$7fd        reserved
 
 $7fe            Speed-select Register: Read & Write
                 (description see further down)
 
 $800-$8ff       IDE-Select 0 (Port 0, Register set 0)
 
 $900-$9ff       IDE-Select 1 (Port 0, Register set 1)
 
 $a00-$aff       IDE-Select 2 (Port 1, Register set 0)
 
 $b00-$bff       IDE-Select 3 (Port 1, Register set 1)
 
 $c00-$cff       IDE-Select 4 (Port 2, Register set 0,
                 Catweasel only!)
 
 $d00-$dff       IDE-Select 5 (Port 3, Register set 1,
                 Catweasel only!)
 
 $e00-$eff       local expansion port, on Catweasel Z-II the
                 Catweasel registers are also mapped here.
                 Never touch, use multidisk.device!
 
 $f00            read only, Byte-access: Bit 7 shows the
                 level of the IRQ-line of IDE port 0.
 
 $f01-$f3f       mirror of $f00
 
 $f40            read only, Byte-access: Bit 7 shows the
                 level of the IRQ-line of IDE port 1.
 
 $f41-$f7f       mirror of $f40
 
 $f80            read only, Byte-access: Bit 7 shows the
                 level of the IRQ-line of IDE port 2.
                 (Catweasel only!)
 
 $f81-$fbf       mirror of $f80
 
 $fc0            write-only: Writing any value to this
                 register enables IRQs to be passed from the
                 IDE ports to the Zorro bus. This mechanism
                 has been implemented to be compatible with
                 harddisks that are either defective or have
                 a buggy firmware and pull the IRQ line up
                 while starting up. If interrupts would
                 always be passed to the bus, the computer
                 might not start up. Once enabled, this flag
                 can not be disabled again. The level of the
                 flag can not be determined by software
                 (what for? Write to me if it's necessary!).
 
 $fc1-$fff       mirror of $fc0
 
 $1000-$ffff     Buddha-Rom with offset $1000 in the rom
                 chip. The addresses $0 to $fff of the rom
                 chip cannot be read. Rom is Byte-wide and
                 mapped to even addresses.
 ==============  ===========================================
 
 The  IDE ports issue an INT2.  You can read the level of the
 IRQ-lines  of  the  IDE-ports by reading from the three (two
 for  Buddha-only)  registers  $f00, $f40 and $f80.  This way
 more  than one I/O request can be handled and you can easily
 determine  what  driver  has  to serve the INT2.  Buddha and
 Catweasel  expansion  boards  can issue an INT6.  A separate
 memory  map  is available for the I/O module and the sysop's
 I/O module.
 
 The IDE ports are fed by the address lines A2 to A4, just as
 the  Amiga  1200  and  Amiga  4000  IDE ports are.  This way
 existing  drivers  can be easily ported to Buddha.  A move.l
 polls  two  words  out of the same address of IDE port since
 every  word  is  mirrored  once.  movem is not possible, but
 it's  not  necessary  either,  because  you can only speedup
 68000  systems  with  this  technique.   A 68020 system with
 fastmem is faster with move.l.
 
 If you're using the mirrored registers of the IDE-ports with
 A6=1,  the Buddha doesn't care about the speed that you have
 selected  in  the  speed  register (see further down).  With
 A6=1  (for example $840 for port 0, register set 0), a 780ns
 access  is being made.  These registers should be used for a
 command   access   to  the  harddisk/CD-Rom,  since  command
 accesses  are Byte-wide and have to be made slower according
 to the ATA-X3T9 manual.
 
 Now  for the speed-register:  The register is byte-wide, and
 only  the  upper  three  bits are used (Bits 7 to 5).  Bit 4
 must  always  be set to 1 to be compatible with later Buddha
 versions  (if  I'll  ever  update this one).  I presume that
 I'll  never use the lower four bits, but they have to be set
 to 1 by definition.
 
 The  values in this table have to be shifted 5 bits to the
 left and or'd with $1f (this sets the lower 5 bits).
 
 All  the timings have in common:  Select and IOR/IOW rise at
 the  same  time.   IOR  and  IOW have a propagation delay of
 about  30ns  to  the clocks on the Zorro bus, that's why the
 values  are no multiple of 71.  One clock-cycle is 71ns long
 (exactly 70,5 at 14,18 Mhz on PAL systems).
 
 value 0 (Default after reset)
   497ns Select (7 clock cycles) , IOR/IOW after 172ns (2 clock cycles)
   (same timing as the Amiga 1200 does on it's IDE port without
   accelerator card)
 
 value 1
   639ns Select (9 clock cycles), IOR/IOW after 243ns (3 clock cycles)
 
 value 2
   781ns Select (11 clock cycles), IOR/IOW after 314ns (4 clock cycles)
 
 value 3
   355ns Select (5 clock cycles), IOR/IOW after 101ns (1 clock cycle)
 
 value 4
   355ns Select (5 clock cycles), IOR/IOW after 172ns (2 clock cycles)
 
 value 5
   355ns Select (5 clock cycles), IOR/IOW after 243ns (3 clock cycles)
 
 value 6
   1065ns Select (15 clock cycles), IOR/IOW after 314ns (4 clock cycles)
 
 value 7
   355ns Select, (5 clock cycles), IOR/IOW after 101ns (1 clock cycle)
 
 When accessing IDE registers with A6=1 (for example $84x),
 the timing will always be mode 0 8-bit compatible, no matter
 what you have selected in the speed register:
 
 781ns select, IOR/IOW after 4 clock cycles (=314ns) aktive.
 
 All  the  timings with a very short select-signal (the 355ns
 fast  accesses)  depend  on the accelerator card used in the
 system:  Sometimes two more clock cycles are inserted by the
 bus  interface,  making  the  whole access 497ns long.  This
 doesn't  affect  the  reliability  of the controller nor the
 performance  of  the  card,  since  this doesn't happen very
 often.
 
 All  the  timings  are  calculated  and  only  confirmed  by
 measurements  that allowed me to count the clock cycles.  If
 the  system  is clocked by an oscillator other than 28,37516
 Mhz  (for  example  the  NTSC-frequency  28,63636 Mhz), each
 clock  cycle is shortened to a bit less than 70ns (not worth
 mentioning).   You  could think of a small performance boost
 by  overclocking  the  system,  but  you would either need a
 multisync  monitor,  or  a  graphics card, and your internal
 diskdrive would go crazy, that's why you shouldn't tune your
 Amiga this way.
 
 Giving  you  the  possibility  to  write  software  that  is
 compatible  with both the Buddha and the Catweasel Z-II, The
 Buddha  acts  just  like  a  Catweasel  Z-II  with no device
 connected  to  the  third  IDE-port.   The IRQ-register $f80
 always  shows a "no IRQ here" on the Buddha, and accesses to
 the  third  IDE  port  are  going into data's Nirwana on the
 Buddha.
 
 Jens Schönfeld february 19th, 1997
 
 updated may 27th, 1997
 
 eMail: sysop@nostlgic.tng.oche.de

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