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

How to convert images for TMS9918A graphics on the RC2014

For me, graphics capability is essential for an 8-bit computer. My graphics chip of choice for the RC2014 is the very capable TMS9918A. It has 15 colours, sprites, several modes and a max resolution of 256x192. It makes arcade-style games possible, such as Tut-Tut above. I enjoy simply displaying images and have a bunch on my CF card (my 'hard drive') and have written image viewer and slideshow apps to display them. Some useful links: Convert9918 Tutorial of Convert9918's settings Multipaint J B Langston's TMS9918A video module my own TMSEMU video module my respository of TMS9918A software, games and .s2/.sc3 images Image conversion I did dabble in writing my own utility to convert .png images but then settled on the Multipaint app which can open a png in a MSX 'screen 2', allow you to tidy it up with paint tools and save as a .sc2 file. (An sc2 file is little more than a video-memory dump and so it's easy to blast that back into vram to display the image.

Driving NeoPixels with Z80

I 've long been thinking about a version two RC2014 LED matrix module . I've had a matrix with a MAX 7219 on a module. It's a nice enhancement. But there's only so much you can do with a single-colour LED array right? Wouldn't it be cool to have RGB LEDs? At Liverpool MakeFest I saw a wall-sized ping-pong ball NeoPixel display and picked up some NeoPixels with the intention of making one. Possibly driven by my RC2014. I enjoy learning about protocols and have had some SPI devices working with the RC2014 - bit-banging SPI works really well because it doesn't care about timing. NeoPixels really do care about timing though. From Adafruit's web page about their 8x8 NeoPixel matrix: If there's one thing I want to get across in this blog post, it's don't just accept what you're told . Question everything. Learn about what's going on and find out why you're being told something isn't possible. Get creative with workarounds. I'

ZX81 reversible internal 16k upgrade

T his post is an upvote for Tynemouth Software's ZX81 reversible Internal 16K RAM upgrade . Their instructions are easy enough for even me to follow and don't involve cutting tracks. This is the ZX81 I've had out on display and used whenever I wanted to. It's an issue 1 and was probably a kit judging by some very untidy assembly. It has a ZX8-CCB composite video mod and an external keyboard fitted. On board it has two 1k x 4-bit chips. The ZX81 originally came with 1k on board. Thanks to a trick with compressing the display in ram, that was enough to type and run a small program but you soon felt the limitations. Back in the early 80s, the solution was a 16k ram pack which plugged into the back[1] and this is the way I've been using this particular machine. These ram packs are notorious for 'ram pack wobble'. Even if fastened into place, you can still randomly find your work disappearing. This is a very reliable solution using a more modern 32k chip (half

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