Background

The Acorn operating system RISC OS is built from a kernel and a collection of software components called relocatable modules. Its native bitmap format is the sprite.

SpriteExtend

RISC OS’s most fundamental sprite drawing routines live alongside the other VDU handling within the OS kernel. However, that’s not enough to support all of the defined sprite operations. A support module called SpriteExtend enters the fray: it hooks into the OS and steps in when required to implement the extended OS_SpriteOp operations.

PrivateEye 3.10 is now available.

PrivateEye is a viewer for Sprites, DrawFiles, JPEGs, ArtWorks, GIFs and PNGs. It also has editing features including bitmap effects and rotation.

Version 3.10 is an update which enhances its handling of JPEGs:

• Progressive JPEGs are now passed straight through to the OS when it is capable of decoding them. This requires RISC OS Select with SpriteExtend 1.30 [circa 2002] or RISC OS 5 with SpriteExtend 1.73 [circa 2016], or later. You can still force JPEG cleaning on from the choices if you wish.
• The information given on JPEGs is enhanced. The source info window [pictured above] will show the details of the file format, being JFIF, Exif, Adobe or a combination thereof; Baseline, Extended Sequential or Progressive DCT coding and whether the packing was Huffman or Arithmetic.
• Hand-in-hand with the above is enhanced colourspace reporting. The “Colours” field will show whether the JPEG is encoded as YCbCr (the most common), YCCK (like CMYK), RGB or CMYK. It will report the number of components used, and the depth of those components too.

I’ve updated the site a few times since my last front-page blog post. So what’s happened lately?

• Art! The Sunrise Set is a collection of, presently, seven drawings of sunlit scenes in a geometric vector style. If you like them, you can download them as 1024x1024-pixel resolution PNGs.

• Wallpaper! I’ve added a new page with chamfered and embossed variations on the “modern” Acorn logo. They are based on the Acorn logo I recreated for my Risc PC in Blender. You can download as 1920x1200-pixel resolution PNGs, or versions tuned for the Archimedes 256-colour palette at 800x600 pixels. You can grab the source files too, if you use Affinity Designer.

• Tweaks! My fantasy Acorn branded hard disc in a diagram type style image thing got tweaked a bit with changed colours and other bits.

• Diagrams! At one point I was working on an article about how to properly wire up Risc PC IDE cables, but drawing a diagram of Risc PC innards ended up being more interesting. I spent some hours drawing two diagrams and never finished the article itself… The two hard disc diagrams are added to the bottom of the hard disc page.

Read about it here.

I’ve been learning how to model 3D objects in Blender by recreating the Acorn Risc PC case.

Read about it here.