{|{{Prettytable|width: 700px; font-size: 2em;}}
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|''Data Bit 7''||''Data Bit 6''||''Function''
|-
| 0 || 0 || Select pen
===== Note =====
This function is not available in the Gate-Array, but is performed by a device at the same I/O port address location. In the CPC464, CPC664 and KC compact, this function is performed in a memory-expansion (e.g. Dk'Tronics 64K RAM Expansion), if this expansion is not present then the function is not available. In the CPC6128, this function is performed by a PAL located on the main PCB, or a memory-expansion. In the 464+ and 6128+ this function is performed by the ASIC or a memory expansion. Please read the document on RAM management for more information.
== Register 0 - Palette Index (Pen selection) ==