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Joystick ports and other refinements

A project log for MSX on RC2014

in which I attempt to make an MSX1 compatible computer using RC2014, keeping to standard RC2014 backplane and modules as far as possible.

shiela-dixonShiela Dixon 07/11/2023 at 15:040 Comments

This week I've received two new modules. 

The first is something that I didn't really consider essential - especially after making such a nice mechanical keyboard. But I find that it makes games so much more fun (and I'm getting better scores!)

The MSX standard allows for two game / general purpose ports. Like everything MSX, it's nowhere near as simple as reading a hardware port.  The ports are read via the sound chip (it has two configurable i/o ports of its own) with some multiplexing.  Therefore this module needs connections to the YM/AY module. I've made a ribbon lead which doesn't look too shabby. 

We already have a similar ribbon between PPI and the keyboard, so the new one between the game port module and AY doesn't look out of place. 

I've been exploring more games and have found a port of the 'fictional' Spectrum game, Nohzdyve, which I absolutely love on the Speccy and this version is even better. It controls a little differently. Rather than simply moving left and right (and continuing to move after you've let go of the key), you still continue to drift left or right, but more slowly than when you actually move left or right. It's hard to explain and not something you immediately notice but makes it more fun to play. Like most of the games I've tried, it supports the joystick.

You can see from the picture above that I'm continuing to use a backplane 8. This is only possible with this new module:

I'm calling this the 'spacesaver'. I respect Spencer's decision to keep the official RC2014 highly modular, but with this project I've found it a little frustrating that the CPU and clock should take two backplane slots. Here we have the Z80, a clock generator and a reset circuit on a single module. The 'enhanced bus' connections are there too if anyone wanted to use this with an enhanced-bus RC2014.  I've fitted this with a 3.58Mhz crystal so that it's specific to the MSX2014 project. The reset circuit means that I no longer have to press the reset button when I power up. 

The whole thing looks very neat. You can see that I'm down to seven modules on a standard backplane 8 (I have a heatsink on my TMS video chip, unfortunately meaning that it hogs the slot in front of it). This works fine if I switch the cartridge ROM module with the tape module as needed (which are mutually-exclusive anyway).

This setup is working beautifully. Unfortunately I've got to order a new version of the joystick module pcb because I had to do some troubleshooting there and found a connection I missed - the version I'm using has a couple of bodge wires. 

Apart from that - what next? I'm not quite sure. I have been tempted to use an enhanced-bus backplane and put those joystick and cassette signals on the enhanced bus. I'm still sleeping on that one. I'd also like to learn about floppy interfaces and possibly get MSXDOS running with a Gotek.

I guess I should get on with some of the software projects that I've started, which for me is the main point of building this computer. Here's some of the cool stuff that I've been messing around with. They include Conway's Life, using RC2014 modules with the MSX, type-ins from a book and from the web.

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