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Aleste 520EX - I/O Ports

575 bytes added, 06:32, 12 February 2010
/* Aleste Gate Array (aka Patasonic's Multiport) */
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== Aleste Gate Array (aka Patasonic's Multiport) (Port 7Fxxh) ==
Aleste "Gate Array" is similar in functionality to the Gate-Array in the CPC/Plus.
{|{{Prettytable|width: 700px; font-size: 2em;}}
|''Data bit 7''||''Data bit 6''||Action
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|0||0||Gate Array Register 0 - Pen Palette index write
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|0||1||Gate Array Register 1 - Pen ink writePalette data
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|1||0||Gate Array Register 2 - Mode, Rom enable, Leds
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|1||1||Gate Array Register 3 - Used by mapperRAM banking
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=== Gate Array Register 0 - Palette Index ===
Pen index:
|4||If set to 1, border is selected
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|3..0||Pen index(ignored if Bit4=1=Border)
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=== Gate Array Register 1 - Palette Data ===
The number is converted by IC D62.
* When MAPPER is not set, the number is equivalent to the CPC's Gate-Array colour value, but this is looked up in IC D62 and converted into a 2-bit per element R,G,B for the aleste video hardware.
* '''Note''' - The CPC supports 3 intensities per color (0%, 50%, 100%), the Aleste supports four intensities (0%, 33%, 66%, 100%). In the CPC-style 27-color mode, the Aleste uses only the dark intensities (0%, 33%, 66%), this gives it a proper ratio (66% being twice 33%), the downside is that the 64-color mode appears brighter - so one may need to adjust brightness on the monitor whenever switching between 27-color and 64-color modes. === Gate Array Register 2 - Video Mode, ROM enable, LEDs ===
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=== Gate Array Register 3 - RAM banking (in CPC-style MAPMOD=0) ===
Controls RAM Banking, similar to the Gate Array on CPC6128 (or, more specific, similar to the 16L8 PAL IC which assists the CPC6128s Gate Array).
'''Actually''', it seems to work more like an [[Inicron RAM-Box]] (which isn't fully compatible with the dk'tronics style [[Standard Memory Expansions]]).
=== Gate Array Register 3 - RAM banking (in Aleste's special MAPMOD=1) ===
Four I/O ports control the mapper:
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