building my own relay computer

[ben]

On 2/14/2015 1:05 AM, Dave G4UGM wrote:
>
>
>> -----Original Message-----
>> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Dale H.
>> Cook
>> Sent: 14 February 2015 03:41
>> To: cctalk at classiccmp.org
>> Subject: Re: building my own relay computer
>>
>> At 08:14 PM 2/13/2015, Ben wrote:
>>
>> The alu has never relay been a problem with relays, but what about main
>> storage? Punched tape (paper/film/card) is no longer with us for I/O.
>>
>
> Punched tape is about. Check out the "green keys" list, 5-level stuff comes
> up from time to time, generally at low cost. There is some ex-CNC items on
> E-Bay at present but for silly prices. Whilst I haven't seen any on E-Bay
> there were three Documation readers advertised on the Vintage Computer
> forums.
>
>
>> Fifty years ago I got around that by building my own card reader (very
> slow)
>> for input and hand-punching Hollerith cards with a hole punch. That was
>> some years before I got access to an IBM card punch in high school. Output
>> was a set of electro-mechanical counters, and they were a real pain to
>> implement.
>>
>
> Many folks have implemented photo electric tape readers, but these tend to
> be clocked off the small feed holes. I guess it wouldn't be too hard to
> build a photo electric reader that has a 3-d printed feed wheel that was
> driven by a stepper motor. In fact I am pretty sure you could even use a
> coil and ratchet arrangement, like this one here:-
>
> http://grabcad.com/library/cam-operated-ratchet-pawl-1
>
> but operated buy a coil and magnet rather than a rotating cam. Some one has
> actually made a complete but operated mechanical punch card computer..
>
> http://observationdeck.io9.com/a-3-d-printed-hand-cranked-punch-card-compute
> r-1481921919
>
> so I don't think its hard. Getting things 3-D printed isn't hard, in fact
> most FabLabs will have one and things can be printed for the cost of
> materials. Also Hack Space...
>
>   I think it's the punch that's harder. You would need to harden the punch
> pins, and the would need to have a very exact fit. I guess a CNC router
> could be used to make these...
>

I think that needs real machine work. Strange what you could do 100 
years ago you can not do today.
Computer controlled stuff is good for may things but not that.
Ben.