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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
-