Bush IBX set-top box port: general merge request threads

Unless asked otherwise, I’m going to keep all my merge request notices for the Bush IBX work here to avoid cluttering up the forum :)

I’ve just opened a merge request for PortMan: https://gitlab.riscosopen.org/RiscOS/Sources/HWSupport/PortMan/-/merge_requests/1

This should fix a crash error which happens on the Bush Internet TV set-top box. Short summary, the driver is pre-HAL and was never updated to deal with running on HAL systems. It also assumes pin names are max. 16 characters, but the pindef file for the Bush box (in the Lazarus directory) has at least one which is longer. That causes a “buffer overflow” error when the module is initialised.

Comments on the changes welcome – and if I forget to say that later, please assume the same for my other proposed changes :)

This is the big merge. These merges add support for the Bush Internet TV, by modifying the HAL and Kernel.

These enable the machine type definition for “Lazarus” (the Bush IBX codename) and add a “no VCO” and “display is a TV” flag to the VDU descriptor device-specific field.

• ADFS: https://gitlab.riscosopen.org/RiscOS/Sources/FileSys/ADFS/ADFS/-/merge_requests/4
• FPASC: https://gitlab.riscosopen.org/RiscOS/Sources/HWSupport/FPASC/-/merge_requests/5
• HdrSrc: https://gitlab.riscosopen.org/RiscOS/Sources/Programmer/HdrSrc/-/merge_requests/22
• Kernel: https://gitlab.riscosopen.org/RiscOS/Sources/Kernel/-/merge_requests/73

Next up, the VIDC20 driver changed. This needs the Kernel MR to go through before it’s merged, but it’s otherwise independent and shouldn’t break anything on desktop platforms.

• VIDC20Video: https://gitlab.riscosopen.org/RiscOS/Sources/Video/HWSupport/VIDC20Video/-/merge_requests/2

And the IOMD HAL fix, which requires basically all of the above

• IOMD HAL: https://gitlab.riscosopen.org/RiscOS/Sources/HAL/HAL_IOMD/-/merge_requests/2

Finally, the Env and Components files needed to actually build the thing:

• Env: https://gitlab.riscosopen.org/RiscOS/Env/-/merge_requests/18
• Components: https://gitlab.riscosopen.org/RiscOS/BuildSys/-/merge_requests/75

This whole pile of MRs adds basic support for the Bush Internet TV set-top box to RISC OS 5. The box can be booted, with a star prompt on the serial port, and generates video. The hardware must be modified for this to work usefully: at a minimum PS/2 mouse and keyboard ports are required. Ideally a TTL serial port (first UART on the SoC) mod should be fitted too.

The STB build is probably going to diverge a little from the main IOMD build target over time — I have the following planned:

• Modify IOMDHAL, Kernel and VIDC20Driver to pass the VIDC RCLK and HCLK clock rates into the video driver from the HAL layer.
  • This opens up options for installing a VIDC HCLK crystal on the IBX to allow for better video timing accuracy in certain modes.

• Add support for Zip drives (now IZipFS and PPADriverJ are in the repos)
• Write a driver for the RCMM infrared keyboard (on the second Super I/O serial port) and add it
• Create and integrate a new component to put some files in ResourceFS:
  • Basic utility programs you’d expect to see in :4.$.Library.
  • A basic !Boot obeyfile to bring the system up.
    • If a Zip disk with a flag file is present, it could boot from it in preference to the ROM.
  • A directory of user files which can be integrated into the build.

There’s also an NC-style user interface mentioned in some of the source code, which I’d like to look into.

For anyone who’s interested in playing with this, I’ve created a branch of the IOMDHAL repository you can recursively-clone, do a submodule update, and hopefully compile and run:

Currently I have my IBX booting off the Zip disk after some *Configure commands. Ideally I need to sit down and work out how to override the default CMOS settings to boot from ResourceFS and set the keyboard up properly, but that’s a job for later.

Ideally I need to sit down and work out how to override the default CMOS settings to boot from ResourceFS

The CMOS blatted in when it’s empty (or has a bad checksum) is held in a table in the kernel, and there’s a means to override that table if needed for having a specific port use differing defaults. For example here’s where the OMAP3 overrides the filing system to SCSIFS.