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Version 5.35, 4.79.2.18. Tagged as 'Kernel-5_35-4_79_2_18'

Version 5.35, 4.79.2.17. Tagged as 'Kernel-5_35-4_79_2_17'

kernel now attempts to substitute video mode numbers in face of h/w with limited bits-per-pixel support (not tested yet)

HAL_API document added - early draft only, of interest to those
writing or modifying HALs for new h/w
ARMop_API document added - early draft only, of interest only
to those modifying kernel to support new ARM cores
*** polite comments on HAL_API welcome ***

Version 5.35, 4.79.2.15. Tagged as 'Kernel-5_35-4_79_2_15'

First attempt at ARM9 support, and general clean-up of old ARM-specific code, now using vectored ARMops.

Not tested.

Version 5.35, 4.79.2.14. Tagged as 'Kernel-5_35-4_79_2_14'

More stuff. Up to the desktop now; cache on, working keyboard. Some source restructuring to start to make splitting it up into several object files more feasible.

Detail:
  Added the HAL NVRAM entries.
  Modified i2cutils to use the HAL entries for NVRAM and behave sensibly if the HAL reports that there is no NVRAM, in which case there must be a forced reset_cmos call so that the cache gets set up sensibly.
Admin:
  Tested under the RPC emulator and appears to be working correctly, although some calls to IIC are still being made in the no nvram case.

Version 5.35, 4.79.2.8. Tagged as 'Kernel-5_35-4_79_2_8'

Version 5.35, 4.79.2.5. Tagged as 'Kernel-5_35-4_79_2_5'

Version 5.35, 4.79.2.2. Tagged as 'Kernel-5_35-4_79_2_2'

* 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'

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'

Not fully tested on all hardware permutations.