Re: 6702 chip

On Sat, 14 Jul 2012, William Levak wrote:

I have rearranged my test program as indicated below.  It does make the 
program shorter and the logic flow simpler.  BUT, to get it to work, I 
have to initialize the shift register to all zeroes, and the last number 
register and the flip-flops to 214.

I don't understand why that should be!


> On Thu, 12 Jul 2012, William Levak wrote:
>
> INITIALIZATION:
>
> The flip-flops are set to 0.
>
> The even/odd register is set to 1.
>
> The last number register is set to 0.
>
> All the shift register positions are set to 0, except the current output 
> positions, which are set to 214.
>
> OPERATION:
>
> 1.  The shift registers output to the flip-flops, which output to the output 
> register.
>
> 2.  The chip waits for input.  If the input is odd and the even/odd register
> is even, continue below.  Otherwise transfer the low bit of the input 
> register to the even/odd register, and continue waiting for input.
>
> 3.  Exclusive or the input with the last number register.  Exclusive or that 
> result with the current position of the shift registers.
>
> 4.  Shift the shift registers one position, and copy the input register to 
> the last number register.
>
> 5.  Go to step 1. and continue indefinitely.
>
> This looks like it will work, but I have not tested it yet.  The advantage is 
> that 214 is set only once. Everything else is normal chip initialization.
>
> It does not explain how the even/odd register is set to one when an odd 
> number is accepted.  There does not appear to be a good place to do it.
> It isn't likely to be done when the exclusive or's are executed.  That would 
> take very precise timing. The most likely time is when the input register is 
> coppied to the last number register, but that would take separate logic than 
> step 2.
>
>
> wlevak@sdf.lonestar.org
> SDF Public Access UNIX System - http://sdf.lonestar.org
>
>      Message was sent through the cbm-hackers mailing list
>

wlevak@sdf.lonestar.org
SDF Public Access UNIX System - http://sdf.lonestar.org

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