Re: DHGR Bit String Question

[Rubywand <rubywand@swbell.net>]

Bryan Parkoff writes ...
> 
>     I have a question about DHGR's order bits.  I display 7 deep red pixels.
> Please look at bit string below.
> 
> 1000100010001000100010001000
> 
>     I only capture 7 bits in this string.  I can add 0 bit or 1 bit in 0th
> bit because they are always the same, which they are not used nor displayed.
> 
> 1000100 0100010 0010001 0001000
> 
> 1000100:0 0100010:0 0010001:0 0001000:1
> 
> 88 44 22 11
> 
>     88 is always in even aux.  11 is always in even motherboard.  22 is
> always in odd aux.  44 is always in odd motherboard.
> 
>     How can you explain why did Apple //e move 11 from odd motherboard to
> even motherboard and 44 from even motherboard to odd motherboard?
> 
>     It does not make sense and it is always puzzled.  Please explain how it
> is done differently?
> 
> Bryan Parkoff


     Red is DHR Color #1. If you have seven DHR red dots starting at the left
side of the screen, then, the bit stream pattern 0001 will be repeated 7 times.
Moving left to right it will look like this:

--->
0001000100010001000100010001


Adding breaks for the 7-bit bytes gives ...

--->
0001000 1000100 0100010 0010001

which gives four-bit values of 1, 1, 1, 1, 1, 1, 1. You have seven red dots.


Since bytes are fed into the stream LSB-first, the bytes in Aux and main memory
(with x for the unused bit 7) are ...

  AUX      Main     AUX      Main
x0001000 x0010001 x0100010 x1000100

Taking x to be 0 you have these four bytes in memory:

AUX:  08 22
Main: 11 44



Rubywand