Sunday, 8 February 2015

ZX Spectrum USB Keyboards

Continuing with the refreshed USB keyboard designs is the ZX Spectrum USB keyboard. There are two versions of this, this being the first, the standalone USB keyboard. The other version is specifically for use with an integrated Raspberry Pi.
The design of these continues to evolve, this time the layout has changed and the mode switch is now in line with the other V2.2 keyboards. I've also shuffled the pins around so there is a byte wide port on the row connector, and 5 contiguous bits from another port for the column connector. This makes the code neater, I'm a bit obsessive about things being neat and orderly, I often will do several revisions of the board to get the nearest layout. It keeps me happy if nothing else.
The large hole in the board anchors it around the central pillar on the Spectrum case. The are holes for mounting pillars at the corners. The USB connector is mounted as far back as possible, so just the strain relief sticks out of the case in the hole previously used by the TV modulator.
One really useful things about these board mounting on the back of the case is it is possible to save a keyboard with damaged membrane tails and connect even very short tails to the board, like the column tail in this example.
The red switch poking out of the mic socket is used to change mode. When powered on, it starts in remapped mode, so the keys will work according to what is printed on them for normal use (i.e. symbol shift + P for ", caps shift + 0 for delete etc.). If you press the mode button on the back, it will beep and go into emulator mode. Here the buttons will map straight through, for use with the fuse spectrum emulator etc. (i.e. symbol shift + 2 give ctrl + 2, caps shift + 0 give shift + 0 etc.). Press it again and it will beep and go back to remapped mode. The beeper also makes a click sound as each key is pressed when not in emulator mode (as fuse makes the click sound).
These board can also be used with the ZX Spectrum Plus, mounted to the back of the keyboard.
I can supply these boards as a conversion kit, complete with USB cable and mounting pillars, just supply a ZX Spectrum or ZX Spectrum Plus.


Price including postage

So there is the completed ZX Spectrum USB keyboard, available for sale now, and one of the most popular items in my Etsy store. Read more about the version of the ZX Spectrum USB keyboard with integrated Raspberry Pi.