Re: BYTE Article of Mega II

["Bryan Parkoff" <nospam@nospam.com>]

"Michael J. Mahon" <mjmahon@aol.com> wrote in message 
8JidnaX0iMkN59fbnZ2dneKdnZydnZ2d@comcast.com">news:8JidnaX0iMkN59fbnZ2dneKdnZydnZ2d@comcast.com...
> Bryan Parkoff wrote:
>
>>     Yeah, it makes sense what 3,000 gates meant.  Hopefully, the answer 
>> will be available to assure which RGB matrix does not have ROM.  I 
>> believe that RGB matrix is constructed by TTL gating.  I am the one 
>> annoying to post in the newsgroups when I am trying to get some answers 
>> from the non-existed research.  I am sure to see how microscope may be 
>> helpful to decap Mega II chip to find RGB matrix information.
>
> What is visible from the surface may not be sufficient to determine
> the logic of the chip.

Michael,

    I am not sure I understand what you mean.  If RGB matrix is a ROM, I am 
sure that four NTSC pixels (16 RGB pixels) out of 140 NTSC pixels (560 RGB 
pixels) will display on the screen at 98% correct.  (Study 16 RGB pixels out 
of 560 RGB pixels per horizontal line for research purpose).  Only 2% error 
is the mismatch color between RGB pixels.  For example, five monochrome 
pixels have five bits.  First one bit is light gray pixel.  Second four bits 
are light gray pixels.  If ROM is used, first one bit would be pink leaving 
second four bits to be same light gray pixel.  (It is mismatch color.)  I 
have a list of errors.
    It is not the practice to locate 7 bits or more bits to determine DHGR 
colors if ROM is used.  It can only determine current four bits to show 
current color before it needs to determine and give correct color on future 
four bits.  It has to do with TTL gating instead of ROM.
    It is difficult for me to explain.  Perhaps, folks are willing to 
participle to see my Microsoft Excel worksheet.  Microsoft Excel worksheet 
helps to explain clearly so they have a better idea to do feedback and write 
small algorithm for testing.  Pick-up table with 4,096 entries is like ROM 
should be avoided.  A small algorithm has two loops.  Outer loop is 0x0000 
through 0xFFFF.  It is like bit stream (monochrome pixels) each horizontal 
line.  Inner loop is 0x00 through 0x0F.  It is for 16 RGB pixels.  Translate 
16 bits (monochrome pixels) to determine one color each pixel out of 16 
pixels each horizontal line out of 65,536 horizontal line.  Simple 
algorithm?  Didn't you?

Bryan Parkoff