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Added 256-colour version of the (high-resolution only) teletext code, and support for teletext when hardware scroll is disabled. Both are required for Tungsten.

Turned off the module init/final service calls, since we still don't have an
allocation for them.
Upped the OS version number to 5.01.

Version 5.35, 4.79.2.53. Tagged as 'Kernel-5_35-4_79_2_53'

Detail:
  Lots of changes since last version, at least the following:
  * Updated OS timestamp, removed alpha status
  * Negative INKEY OS version changed to &AA
  * GraphicsV is now alocated vector number &2A
  * ROM moved up to &FC000000
  * Max application slot increased to 512 Mbytes (for now)
  * Max size of RMA increased to 256 Mbytes
  * RMA is now first-created dynamic area (so it gets lowest address after
    top of application slot)
  * OS_Memory 10 reimplemeted
  * New OS_ReadSysInfo 6 values 18-22 added
  * OS_ReadSysInfo 8 gains flag bit to indicate soft power-off
  * Misc internal top-bit-set-address fixes
  * *ChangeDynamicArea can take sizes in megabytes or gigabytes
  * Magic word "&off" in R0 passed to OS_Reset powers down if possible
  * Added acceleration: block copy; CLS; text window scroll up; rectangle
    fill
  * Disabled LED flashing in page mode (liable to crash)
  * Masked sprite plot and VDU 5 text avoids reading the screen if possible
  * Framestore made USR mode accessible
  * Fix for VDU 5,127 bug - now relies on font definitions being in extreme
    quarters of memory, rather than bottom half
  * Allocated 64-bit OS_Convert... SWIs
  * IIC errors use allocated error numbers
  * Looks for Dallas RTC before Philips RTC because we're using a Philips
    NVRAM device with the same ID
  * Fix to bug that meant the oscillator in the Dallas RTC wasn't enabled
  * Default mouse type (USB) changed to allocated number
  * Ram disc max size increased to 128 Mbytes (Ursula merge) and made
    cacheable for StrongARMs (not XScale)
  * Branch through zero handler now works in USR mode, by use of a
    trampoline in the system stack to allow PC-relative register storage
  * Address exception handler changed to not use 0 as workspace
  * OS_Memory 13 extended to allow specification of cacheability and access
    privileges
  * Added OS_Memory 16 to return important memory addresses
  * RISCOS_MapInIO() takes cacheable flag in bit 3, access permissions in
    bits 10 and 11, doubly-mapped flag in bit 20, and access permissions
    specified flag in bit 21
  * Bug fix in last version for application abort handlers didn't quite
    work; register shuffle required
  * "Module is not 32-bit compatible" error now reports the module name
  * Default configured language changed from 10 to 11 (now Desktop again)

Version 5.35, 4.79.2.51. Tagged as 'Kernel-5_35-4_79_2_51'

Version 5.35, 4.79.2.48. Tagged as 'Kernel-5_35-4_79_2_48'

Ursula. Quite a hairy code merge really, so let's hope it is
worth it to someone. What you get (back after 2 or 3 years):
- much more efficient for largish numbers of DAs (relevance
  to current build = approx 0)
- fancy reason codes to support fast update of
  Switcher bar display (relevance = 0)
- support for clamped maximum area sizes, to avoid address
  space exhaustion with big memory (relevance = 0)
- better implementation of shrinkable DAs, performance
  wise (if lots of DAs, relevance = approx 0)
- support for 'Sparse' DAs. Holey dynamic areas, Batman!
  (relevance, go on someone use the darned things)
Moderately development tested on HAL/32bit ARM9 desktop.
Note the Switcher should be compiled to use the new
reason codes 6&7, for fabled desktop builds.

Also, during this work, so I could see the wood for the
trees, redid some source code clean up, removing pre-Medusa
stuff (like I did about 3 years ago on Ursula, sigh). That's
why loads of source files have changed. The new DA stuff
is confined pretty much to hdr.KernelWS and s.ChangeDyn.

Ta.

Version 5.35, 4.79.2.38. Tagged as 'Kernel-5_35-4_79_2_38'

further kernel/HAL split work in video area almost-HAL code for VIDC20/IOMD in vdu.vduhint, now almost divorced from kernel workspace tested briefly in Ursula desktop environment

Version 5.35, 4.79.2.4. Tagged as 'Kernel-5_35-4_79_2_4'

* Added ARM_IMB and ARM_IMBRange SWIs as recommended by ARMv5.
* Some early prototype HAL bits popped in - a lot of source restructuring still
  to come.
* New debug target creates an AIF image with debug information, and translates
  this into an ASCII object file for the 16702B logic analyser.

Version 5.35, 4.79.2.1. Tagged as 'Kernel-5_35-4_79_2_1'

Added compile-time support for full-resolution teletext characters in teletext emulation mode (MODE 7) for that authentic BBC Micro feel.

  Also introduced a few useful teletext control features via VDU 23,18.
  Unrelatedly, fixed *ScreenLoad to work for interlaced displays.

Detail:
  The new typeface is designed on a 16x20 grid (previously we had used 8x10),
  so it uses a screen resolution of 640x500 pixels (rather than 320x250).
  Since we have been unable to source a genuine teletext font, and since
  examination of a BBC Micro suggests that the genuine font may not have been
  a power-of-2 pixels wide, I have designed one specially, based upon the one
  supplied in Zap distributions (a 12x20 font). Rather than increase the
  amount of workspace that the kernel requires for cacheing graphic
  characters, it now generates them on the fly, as they are required; this
  should only add about 25% to their rendering time.

  The new VDU 23 sequences are as follows:

  VDU 23,18,0,mode,0,0,0,0,0,0
    Switch transparency mode
      mode = 0: "Text" mode: the whole display is set opaque
      mode = 1: "Mix" mode: foreground colours, and both foreground and
        background of boxed text are opaque; non-boxed background colours are
        all transparent
      mode = 2: "Box" mode: boxed regions are opaque, others are transparent
      mode = 3: "TV" mode: the whole display is set transparent
    Default is mode = 0.

  VDU 23,18,1,suspend,0,0,0,0,0,0
    Suspend or resume bitmap updates
    This call allows an application to request that the kernel suspends
    updates to the framebuffer bitmap. This allows for a significant speed
    increase in the rendering time for a large amount of text, for example
    when redrawing a complete teletext page, because each time you plot a
    single character, it can cause the whole of the rest of the line to be
    re-rendered. When you switch out of suspend mode, the whole screen is
    refreshed in a single pass. Note that the appearance of the display is
    undefined is you cause a hardware scroll while in suspend mode.
      suspend = 0: screen update is enabled
      suspend = 1: screen update is suspended
    Default is suspend = 0.

  VDU 23,18,2,reveal,0,0,0,0,0,0
    Reveal/conceal
      reveal = 0: characters between the Conceal control code and the next
        colour control code are replaced by spaces
      reveal = 1: all characters are displayed
    Default is reveal = 0.

  VDU 23,18,3,black_emable,0,0,0,0,0,0
    Enable/disable black foreground colour control codes
      black_enable = 0: control codes &80 and &90 do nothing
      black_enable = 1: control code &80 selects black text, control code
        &90 selects black graphics
    Default is black_enable = 0.

  I have performed some timing tests on the rendering of complete teletext
  pages grabbed from the teletext server. These show that the new code
  generally imposes a 2x speed hit. However, when using the VDU 23,18,1
  suspend function, this improves to a 20% speed increase when compared to
  the old low-resolution code. Better still, because the framebuffer is only
  being updated for the final stage of this process, the screen *appears* to
  be updated some 3x faster than with the old code!

  A comment on the VDU variable Log2BPC is in order: in previous kernels,
  this was able unambiguously to refer to both the framebuffer width of a
  character in bytes, and the framebuffer width of an "addressable pixel" in
  bits; this no longer works with the 16-pixel wide teletext font. Bearing
  in mind that future kernels may support Unicode system fonts where the
  width varies from character to character, I have chosen to fix Log2BPC to
  the "addressable pixel" definition.

Admin:
  Requires HdrSrc 0.89 and (for non-desktop builds) Interlace 0.61. A monitor
  definition file containing a definition for a 640x500 screen mode is also
  required; version 0.40 of ModeFiles contains a suitable mode for STB-400.

  Tested fairly rigourously on an Ursula build, a Lazarus build and an
  STB-400 build, using genuine teletext pages and Yellow River Kingdom.

Version 5.30. Tagged as 'Kernel-5_30'

Detail:
  In the previous version, Portable_Idle was called each time that the callback
  chain was examined. This is only desirable in cases where we're polling the
  keyboard, waiting before scrolling the text window; in the normal case, it's
  an unnecessary slow-down. Now fixed to only call Portable_Idle if we're
  waiting for a key up/down/timeout.
Admin:
  Not tested.

Version 5.28. Tagged as 'Kernel-5_28'

  In particular, they can go off when Scroll Lock etc have frozen the text
  output.
Detail:
  The callback chain is examined at least once per line scroll. Additionally,
  it is examined repeatedly while Scroll Lock or Ctrl-Shift are acting, while
  idling between lines if Ctrl is held down, and while waiting for the Shift
  key to be pressed at the bottom of a screen when in page mode.
  The opportunity is also taken to call Portable_Idle after each time that the
  callback chain has been examined.
Admin:
  Not tested.

Version 5.27. Tagged as 'Kernel-5_27'

Details:
  The Kernel will now compile to produce a pure 32-bit system if No26bitCode is
  set to TRUE.
  If No26bitCode is FALSE, then the Kernel will be a standard 26-bit Kernel,
  although some internal changes have taken place to minimise compile
  switches between the two cases. See Docs.32bit for more technical info.

  The hardest part was the flood-fill...

Other changes:
  Pointer shape changes now take place on the next VSync, rather than actually
  WAITING for the VSync. Turning the Hourglass on shouldn't slow your machine
  down by 5% now :)

  Lots of really crusty pre-IOMD code removed.

Admin:
  Tested in 32 and 26-bit forms in a limited desktop build. Basically, this
  will need to see a lot of use to iron out difficulties. I'd like anyone who
  has a non-frozen project to at least attempt using this Kernel.

Version 5.23. Tagged as 'Kernel-5_23'