Subversion Repositories pentevo

video resolution:

lowres - 7MHz pixelclock (256 or 320 pixels per line)
hires  - 14MHz pixelclock (512 or 640 pixels per line)


videomode:

attr   - two bytes per 8 pixels, bits and attribute
text   - 2 bytes per 8 pixels, same as attr, but bytes are letter code and letter attribute
16c    - 4 bits per pixel, 16 colors
2c     - one bit per pixel, monochrome
256c   - 8 bits per pixel
16+16c - two 16c playfields with transparency


table structure:

MEMORY SPEED
        VIDEO MODE
                CPU SPEED/WAITS


BW - available memory bandwidth usage: when 1, cpu stalls, when 1/2 or less - CPU runs nowait at Fcpu<=Fmemory.
     When Fcpu>Fmemory and BW<1, there are wait states.


-----------------------------------------------------------------------------------------

3.5MHz, 8 bit memory:

        lowres attr/text,
        hires 2c:         BW=1/2
                3.5MHz nowait
                7MHz wait
        lowres 16c,
        hires attr/text:  BW=1
                stall


3.5MHz, 16 bit memory:

        lowres attr/text: BW=1/4 (or 1/2 in lame schemes like ATM turbo or Profi)
                3.5MHz nowait
                7MHz wait
        lowres 16c,
        hires attr/text:  BW=1/2
                3.5MHz nowait
                7MHz wait
        lowres 256c,
        lowres 16+16c,
        hires 16c:        BW=1
                stall


7MHz, 16 bit memory:

        lowres attr/text,
        hires 2c:         BW=1/8
                3.5MHz nowait
                7MHz nowait
                14MHz wait
        lowres 16c,
        hires attr/text:  BW=1/4
                3.5MHz nowait
                7MHz nowait
                14MHz wait
        lowres 256c,
        lowres 16+16c,
        hires 16c:        BW=1/2
                3.5MHz nowait
                7MHz nowait
                14MHz wait
        hires 256c,
        hires 16+16c:     BW=1
                stall