Video DAC: Difference between revisions
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[[File:mvs_viddac.jpg|right|thumb|Resistor array forming the video DAC on a 1FZS | [[File:mvs_viddac.jpg|right|thumb|Resistor array forming the video DAC on a 1FZS.]] | ||
The NeoGeo video DAC | The NeoGeo uses a discrete video DAC made of precision resistors, and two 74LS273 latches controlled by [[NEO-B1]], [[NEO-GRC]] or [[NEO-GRZ]]. | ||
[[File:aes_viddac.png|right|thumb|Video DAC on a AES board.]] | |||
[[File:aes_viddac_schematic.png]] | |||
Each color component has its own set of 7 resistors. 6 of them are used with the actual color value stored in the [[palette RAM]] (5 + 1 [[Palettes#Dark bit|common bit]]). The last (SHADOW signal) is related to the REG_DISPDISABLE and REG_DISPENABLE registers (74HC259 latch). | |||
The output voltage is then divided by 5 to obtain a 1Vp-p max signal, which can be fed to the [[CXA1145]] encoder. | |||
[[Category:Chips]] | [[Category:Chips]] | ||
[[Category:Video system]] | [[Category:Video system]] | ||
Revision as of 13:17, 8 February 2011
The NeoGeo uses a discrete video DAC made of precision resistors, and two 74LS273 latches controlled by NEO-B1, NEO-GRC or NEO-GRZ.
Each color component has its own set of 7 resistors. 6 of them are used with the actual color value stored in the palette RAM (5 + 1 common bit). The last (SHADOW signal) is related to the REG_DISPDISABLE and REG_DISPENABLE registers (74HC259 latch).
The output voltage is then divided by 5 to obtain a 1Vp-p max signal, which can be fed to the CXA1145 encoder.