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screen_map [2016/05/22 20:14] ex_writer |
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| - | ====== Screen Map ====== | ||
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| - | In the Bally Professional Arcade, two bits of RAM define each screen pixel. Therefore, one 8-bit byte of RAM defines four pixels on the screen. | ||
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| - | In the low-resolution model, 40 bytes define a line of screen data, providing a horizontal resolution of 160 pixels. The vertical resolution is 102 lines. Therefore, the screen requires 102 x 40 = 4,080 bytes. The remaining 16 bytes of screen RAM are used for [[scratchpad]]. More RAM can be reserved for [[scratchpad]] by [[blanking]] the screen before the 102nd line. | ||
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| - | [High-resolution explanation omitted.] | ||
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| - | The first byte of RAM is in the upper lefthand corner of the screen. As the RAM address increases, the screen position moves in the same direction as the TV scan—left-to-right and top-to-bottom. The four pixels in each byte are displayed with the least significant pixel, defined by bits 0 and 1, on the right. | ||
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| - | {{screen_map.png}} | ||
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| - | [NM:85–6] | ||
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