Changes
CRTC
,/* CRTC Differences */
|(C9=R9 and C0=R0) or (C9=0 and C0=0 to R0-1)
|}
=== Reading from CRTC registers on ASIC/Pre-ASIC ===
On CRTC Types 3 and 4, only the 3 least significant bits of the selected register number are considered to read a register according to the following table:
{|{{Prettytable|width: 700px; font-size: 2em;}}
|'''Nb'''||'''Register'''||'''Definition'''
|-
|0||16||Light Pen Address (High)
|-
|1||17||Light Pen Address (Low)
|-
|2||10||Cursor Start Raster
|-
|3||11||Cursor End Raster
|-
|4||12||Display Start Address (High)
|-
|5||13||Display Start Address (Low)
|-
|6||14||Cursor Address (High)
|-
|7||15||Cursor Address (Low)
|}
Therefore, as an example, reading register 4 will give the same result as reading register 12 or 20.
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