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- Lines: 122
Tue May 11 09:57:14 1999
- Orig file:
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.2.7/linux/arch/m68k/q40/README linux/arch/m68k/q40/README
@@ -0,0 +1,121 @@
+Linux for the Q40
+You may try http://www.geocities.com/SiliconValley/Bay/2602/ for
+some up to date information. Booter and other tools will be also
+available from this place and ftp.uni-erlangen.de/linux/680x0/q40/
+Hints to documentation usually refer to the linux source tree in
+/usr/src/linux unless URL given.
+It seems IRQ unmasking can't be safely done on a Q40. Autoprobing is
+not yet implemented - do not try it! (See below)
+For a list of kernel commandline options read the documentation for the
+particular device drivers.
+The floppy imposes a very high interrupt load on the CPU, approx 30K/s.
+When something blocks interrupts (HD) it will loose some of them, so far
+this is not known to have caused any data loss. On hihgly loaded systems
+it can make the floppy very slow. Other Q40 OS' simply poll the floppy
+for this reason - something that can't be done in Linux.
+Only possible cure is getting a 82072 contoler with fifo instead of
+drivers used by the Q40, appart from the very obvious (console etc.):
+ drivers/char/q40_keyb.c # use PC keymaps for national keyboards
+ serial.c # normal PC driver - any speed
+ lp.c # printer driver
+ char/joystick/* # most of this should work
+ block/q40ide.c # startup for ide
+ ide* # see Documentation/ide.txt
+ floppy.c # normal PC driver, DMA emu in asm/floppy.h
+ # and arch/m68k/kernel/entry.S
+ # see drivers/block/README.fd
+Various other PC drivers can be enabled simply by adding them to
+arch/m68k/config.in, especially 8 bit devices should be without any
+problems. For cards using 16bit io/mem more care is required, like
+checking byteorder issues, hacking memcpy_*_io etc.
+Upon startup the kernel will usually output "ABCQGHIJ" into the SRAM,
+preceded by the booter signature. This is a trace just in case something
+went wrong during earliest setup stages.
+*Changed* to preserve SRAM contents by default, this is only done when
+requested - SRAM must start with '%LX$' signature to do this. '-d' option
+to 'lxx' loader enables this.
+SRAM can also be used as additional console device, use debug=mem.
+This will save kernel startup msgs into SRAM, the screen will display
+only the penguin - and shell prompt if it gets that far..
+Serial console works and can also be used for debugging, provided serial
+Most problems seem to be caused by fawlty or badly configured io-cards or
+harddrives anyway..there are so many things that can go wrong here.
+Make sure to configure the parallel port as SPP for first testing..the
+Q40 may have trouble with parallel interrupts.
+Q40 Hardware Description
+This is just an overview, see asm-m68k/* for details ask if you have any
+The Q40 consists of a 68040@40 MHz, 1MB video RAM, up to 32MB RAM, AT-style
+keyboard interface, 1 Programmable LED, 2 8bit DACs and up to 1MB ROM, 1MB
+Most interfacing like floppy, hd, serial, parallel ports is done via ISA
+slots. The ISA io and mem range is mapped (sparse&byteswapped!) into separate
+regions of the memory.
+The main interrupt register IIRQ_REG will indicate whether an IRQ was internal
+or from some ISA devices, EIRQ_REG can distinguish up to 8 ISA IRQs.
+The Q40 custom chip is programmable to provide 2 periodic timers:
+ - 50 or 200 Hz - level 2, !!THIS CANT BE DISABLED!!
+ - 10 or 20 KHz - level 4 (and possibly 6 - hardware decoding..)
+Linux uses the 200 Hz interrupt for timer and beep by default.
+q40 master chip handles only level triggered interrupts :-((
+further limitation is no disabling etc. Unless someone finds
+some ingenious clue this means autoprobing will never work.
+Parallel port interrupts cause most trouble..
+IRQ sharing is not yet implemented.
+q40 receives AT make/break codes from the keyboard, these are translated to
+the PC scancodes x86 Linux uses. So by theory every national keyboard should
+work just by loading the apropriate x86 keytable - see any national-HOWTO.
+Unfortunately the AT->PC translation isn't quite trivial and even worse, my
+documentation of it is absolutely minimal - thus some exotic keys may not
+behave exactly as expected.
+There is still hope that it can be fixed completely though. If you encounter
+problems, email me idealy this:
+ - exact keypress/release sequence
+ - 'showkey -s' run on q40, non-X session
+ - 'showkey -s' run on a PC, non-X session
+ - AT codes as displayed by the q40 debuging ROM
+btw if the showkey output from PC and Q40 doesn't differ then you have some
+classic configuration problem - don't send me anything in this case
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