Re: BYTE Article of Mega II

Bryan Parkoff wrote:
"Michael J. Mahon" <mjmahon@xxxxxxx> wrote in message news:8JidnaX0iMkN59fbnZ2dneKdnZydnZ2d@xxxxxxxxxxxxxx

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 work***. Microsoft Excel work*** 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?

What I meant was that if you take the top off the chip and look at
it with a microscope, you may not be able to correctly determine
the circuit of the chip. Reverse engineering a chip often requires
grinding, etching, etc., not just looking.

-michael

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