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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