[Coco] USB keyboard interface for CoCo

[camillus Blockx]

The coco3 keyboard connecter has 15 pins but I think 1 is not used or even
connected. So that gives you an I/O pin more on your pic. Then for the
MC88XX for dana's project or os9cloud, I found a source. The MT68H811xxxx
(cpu) was harder to find, but I found them on ebay.

good luck and pls keep us posted
cb


On Thu, Nov 29, 2012 at 8:05 PM, Steven Hirsch <snhirsch at gmail.com> wrote:

> On Thu, 29 Nov 2012, Phill Harvey-Smith wrote:
>
>  On 29/11/2012 15:18, Gustavo Ranaur Schoenaker wrote:
>>
>>> The main problem is that the regular (e.g. non MEGA) arduino has 12 pins,
>>> two used by the serial port. The CoCo Keyboard uses 15 ports. My first
>>> try
>>> will be to use a MUX/DEMUX chip to to the job (and protect the precious
>>> CoCo PIC). If it doesn't work I would try to use the analog ports.
>>>
>>
>> What I did in a similar situation was used a crosspoint switch between
>> the AVR and the CoCo, one such as the MT8816A 16x8 switch available here :
>>
>> http://www.futurlec.com/**ICSFZarlink.shtml<http://www.futurlec.com/ICSFZarlink.shtml>
>>
>> This only needs 10 lines to drive it, you could probably get away with 8
>> for a CoCo keyboard as you would only need 8x8, so the topmost bit on the X
>> could be pulled high or low, and you could use a simple R-C array for the
>> reset pin, that leaves you with 3 pins for X, 3 for Y, 1 for data (switch
>> at XY open or closed), and one for write strobe.
>>
>> This also has the advantage that the PIA in the CoCo will see it as an
>> array of switches, just like the real keyboard.
>>
>
> Dana Peters' PS2-to-CoCo adapter (later sold by Cloud-9) used a crosspoint
> switch.  I once looked into building one from Dana's original plans, but
> ISTR that the Mitel MT88xx parts were not readily available.
>
> Steve
>
>
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