2019-06-28 22:54:57 -04:00
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# Interfacing a PS/2 keyboard
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Serial connection through ACIA is nice, but you are probably plugging a modern
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computer on the other side of that ACIA, right? Let's go a step further away
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from those machines and drive a PS/2 keyboard directly!
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## Goal
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Have a PS/2 keyboard drive the stdio input of the Collapse OS shell instead of
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the ACIA.
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**Status: work in progress**
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## Gathering parts
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* A RC2014 Classic that could install the base recipe
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* A PS/2 keyboard. A USB keyboard + PS/2 adapter should work, but I haven't
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tried it yet.
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* A PS/2 female connector. Not so readily available, at least not on digikey. I
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de-soldered mine from an old motherboard I had laying around.
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* ATtiny85/45/25 (main MCU for the device)
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* 74xx595 (shift register)
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* 40106 inverter gates
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* Diodes for `A*`, `IORQ`, `RO`.
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* Proto board, RC2014 header pins, wires, IC sockets, etc.
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* [AVRA][avra]
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## Building the PS/2 interface
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TODO. I have yet to draw presentable schematics. By reading `ps2ctl.asm`, you
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might be able to guess how things are wired up.
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It's rather straigtforward: the attiny reads serial data from PS/2 and then
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sends it to the 595. The 595 is wired straight to D7:0 with its `OE` wired to
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address selection + `IORQ` + `RO`
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## Using the PS/2 interface
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2019-06-29 14:25:18 -04:00
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After having built and flashed the `glue.asm` supplied with this recipe, you end
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up with a shell driven by the PS/2 keyboard (but it still outputs to ACIA).
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2019-06-28 22:54:57 -04:00
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2019-06-30 14:16:00 -04:00
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There are still a few glitches, especially at initialization or at connect and
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disconnect, but it otherwise works rather well!
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2019-06-28 22:54:57 -04:00
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[avra]: https://github.com/hsoft/avra
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