New MSX graphics / sound / joystick module for RC2014 / RCBus

I'm impressed at what Les has packed onto this standard-sized module. It contains an FPGA replacement for the TMS9918A, a YM/AY sound module and joystick interface.

The project is open-source and is here.

In MSX terms this is the VDP (vidio display processor) and PSG (programmable sound generator), thus being an alternative for both the J B Langston TMS9918A video module and Ed Brindley's YM/AY sound module and adds two joystick ports to boot. All on a single module for RC2014 or compatible computers.

There's no room for the d-sub joystick ports, so headers are provided so that these ribbon cables can be used.

This is a neat solution for those wishing to take advantage of Les' MSX8 system, which loads most MSX rom files along with a modified MSX BIOS from CP/M on a ROMWBW RC2014.

It is hard-wired to the MSX ports for the sound and video, so it won't be suitable for those wanting to run Colecovision ROMs, for example.

I'm torn myself between the real TMS chip and modern substitutes. It's good to use the real chips - why else would you build the real hardware rather than use an emulator? But the video output of the real TMS9918A (on the monitors I use anyway) leaves a bit to be desired - it is blurry and full of strong artefact colours where dark meets light. HDMI (or DVI in this case) is way more convenient than composite. These are the reasons why I've been developing my own replacement for that chip.

I've been excited about the release of this module because it makes a serious improvement to my MSX2014, which builds an MSX-compatible computer on an RC2014 backplane. There have been a couple of problems with that. First is the number of connections between modules, in particular between the AY module and joystick module. Second is that I've had trouble getting my own HDMI module working with full MSX (various reasons, I'm still working on that). Les' module solves both of these issues. The HDMI output is amazing and as long as I don't want to load from cassette, I have no flying wires between modules.

It's not quite a single-board MSX. You still need CPU, RAM/ROM (with 'slot select'), clock and PPI and optionally cartridge rom. But my MSX2014 is much neater and has more free slots.

As far as the RC2014 goes, Les and the community are still ironing a few things out as I write this, and MSX BASIC with MSX8 is still an ongoing development, but I believe many of the MSX ROMs will load and play perfectly with joystick and certain keys can be used.

I've made and tested a couple of spare ones. If you're interested in one of those, assembled, tested and complete with AY chip and the joystick ribbon cables, they're now on Tindie here.

Comments

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