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Groups > comp.sys.apple2.programmer > #5385

Re: IIGS - Linear mapping?

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Actually there is a bug in my timing table (one also needs RAS for the cpu).
This means that one has to use both the rising and falling edges of the 14M clock to load the address bus.
Maybe something like:


14M clock
---------
0 cycle 0      load video row address
1              assert RAS
0 cycle 1      load first video column address
1              assert CAS
0 cycle 2      -
1              -
0 cycle 3      -
1              latch first 16 bits of video data
0 cycle 4      deassert CAS
1              -
0 cycle 5      load second video column address
1              assert CAS
0 cycle 6      -
1              -
0 cycle 7      -
1              latch second 16 bits of video data
0 cycle 8      deassert CAS & RAS 
0 cycle 8      -
1              -
0 cycle 9      load row address for cpu access
1              assert RAS
0 cycle 10     load column address for cpu access
1              assert CAS
0 cycle 11     -
1              -
0 cycle 12     -
1              latch 8 bits of cpu data 
0 cycle 13     deassert CAS & RAS
1              - 

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IIGS - Linear mapping? paul.s.macmillan@gmail.com - 2018-11-06 11:11 -0800
  Re: IIGS - Linear mapping? James Davis <JPD.Enterprises@outlook.com> - 2018-11-07 00:06 -0800
    Re: IIGS - Linear mapping? kegs@provalid.com (Kent Dickey) - 2018-11-07 08:23 -0600
      Re: IIGS - Linear mapping? John Brooks <jbrooks@blueshiftinc.com> - 2018-11-07 08:35 -0800
        Re: IIGS - Linear mapping? kegs@provalid.com (Kent Dickey) - 2018-11-07 23:29 -0600
          Re: IIGS - Linear mapping? John Brooks <jbrooks@blueshiftinc.com> - 2018-11-08 15:14 -0800
            Re: IIGS - Linear mapping? Dagen Brock <dagenbrock@gmail.com> - 2018-11-09 02:03 -0800
              Re: IIGS - Linear mapping? John Brooks <jbrooks@blueshiftinc.com> - 2018-11-09 14:53 -0800
            Re: IIGS - Linear mapping?  <leonb@novabbs.i2p> - 2020-01-24 22:07 +0000
            Re: IIGS - Linear mapping?  <leonb@novabbs.i2p> - 2020-01-24 22:29 +0000
              Re: IIGS - Linear mapping? Antoine Vignau <antoine.vignau@laposte.net> - 2020-01-24 20:15 -0800

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