Re: Give all devices on a serial IEC bus unique numbers?
Date: 2006-07-16 12:08:37

On 2006-07-09, at 10:27, Spiro Trikaliotis wrote:

> Hello,
> in the German forum C64forum (cf.
> ), an interesting question came up: The person posting there would  
> like
> to see the following functionality added to OpenCBM:
> He wants a function which gives every device attached to the serial  
> bus
> a unique device number. Ideally, the one nearest to the computer  
> (or the
> farest one, it does not matter) gets the 8, the next one the 9, and so
> on.
> He says that he had had a C64 copy program with exactly that
> functionality, but he cannot find it anymore.
> All solutions for such a thing require very exact timing measurements,
> something which is not possible with the 154x/157x/1581 hardware. Does
> anyone here have a good idea how this could be accomplished?


> The person posting there already has some ideas:


> Disadvantage: The numbers will not be sorted from the nearest to the
> farest, but completely random.
> Oh, another idea comes to my mind, similar to the protocol used on the
> CAN bus:


> Again, the big disadvantage: The numbers will be random, not from
> nearest to farest.
> What do you think? Is there a better approach then the one proposed
> there?

Since nobody answered this - it seems "no" ;-) I was refraining from  
answering for some time as I hoped I could somehow be wrong but: if  
the IEC bus is just a passive, pass-though, whatever we call it -  
bus, I see no way to distinguish the position of the device on the  
bus unless we were able to measure over-the-wire signal propagation  

> Additionally, from where could I get a true random number in the
> floppy?

Hm, a "true random" you rather get nowhere but even a kind of quasi- 
random may be tough to get from the floppy. Thinking aloud... maybe  
feeding some timers with off-the-(magnetic)head readout?

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