[GreenKeys] 8-Level TD?

[Javier Albinarrate]

I should have reread the whole thing hahah was thinking faster than 
reading :)

You DO HAVE an ASR33....  I misread...

So you're fine with the 8 bits architecture then (although you'll need a 
lot more relays hahaha)... that's not my case :)

Regards!
Javier


On 22/11/2013 15:53, Javier Albinarrate wrote:
> Hi Cory!
>
> Well I already spammed your mailbox with all the pesky details of my 
> project :)
> In any case, for the records I suggest the following approach instead.
>
> Have lemons? make lemonade
> Forget 8 bits, who needs them? Use 6 bits with 5 bits I/O.
>
> 1- 6 bits architecture: 6 bits data 12 bits address
> 2- 6 bits instruction set with the following characteristics:
>     - You need an extremely well thought instruction set, as baudot is 
> not very binary friendly
>     - Avoid special characters, like LTRS & FIGS
>     - Most common actions in the LTRs range (single word because you 
> use no shift)
>     - Jumps and not so often instructions in the FIGs range (2 words)
>     - Optional extended set (using just 1 instruction in the FIGS 
> range, extends another 8 instructions with an extra decoder)
>     - You need to think in detail each instruction to make it fit in 
> the available ranges, and you need to remember that you can use any 
> bit order for decoding, it is arbitrary (you need to tame baudot)
> 3- The brain
>     - A resettable sequencer of 10 steps
>     - A couple of muxes and demuxes, for instructions and addresses
>     - A matrix of sockets, where you plug diodes 1N4007. Voilá... you 
> have microcoding. That is the core of the design, because it makes 
> everything EASY and FLEXIBLE.
> 4- IO:
>     - Dulpex current loop for IO to the TTY in 5 bits. (otherwise with 
> everything in a single loop it is a mess to control)
>     - 6 bits buffer out and another 6 bits buffer in using relays.
>     - You need to keep the SHIFT status and eventually insert / remove 
> the LTRS and FIGS. This is just a little logic block.
>     - Option A for sequencing: fast reed relays. Option B: Dekatron 
> with vacuum tubes (lots of triodes there, probably cheap russian 
> submini triodes would do it).
> 5- RAM:
>     - Cheap option? Solid state
>     - Bulky option?  Latched relays (I am lucky, I have 1k of them)
>     - Weird option? Neons (many cheap russian IN2 and quite a few tiny 
> russian thyratrons)
>     - Magnetic option? Core. You can get loads of ferrite cores for no 
> money, but it will require a lot of solid state to drive and address.
>
> Regards!
>
> Javier
> LU8AJA
>
>
>
>
> On 22/11/2013 15:15, Cory Heisterkamp wrote:
>>
>> Hey Guys,
>>
>> Looking for some brainstorming here. For the last couple years I've 
>> been planning on building a computer entirely out of relays, with 
>> minimal support from vacuum tubes, Dekatrons, etc. But no transistors 
>> or IC's allowed! I have most of the design worked out and plan on 
>> using my ASR33 for the terminal. Life would be so much simpler if the 
>> communication were parallel, but that feels like a bit of a cheat (I 
>> see why Flexowriters were so popular back in the day for computer 
>> work). I have a Model 28 Receiving-Selector which was Teletype's 
>> version of a serial-to-parallel converter. Did they ever make an 
>> 8-level version?
>>
>> My idea is this... Basically, my output buffer holds a byte at a time 
>> in 8 relay latches. When ready to send my data out to the world, the 
>> holding magnet of the distributor could release, the distributor 
>> would effectively "sample" the state of each of the 8 latches, and as 
>> it returned to the home position, trips the reset line on the buffer 
>> to clear it and it's ready for the next byte to be loaded.
>>
>> The trick is finding an 8-level piece of equipment to start from. Any 
>> thoughts?-Cory
>>
>>
>>
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