Nonstandard Display Controller Registers
Index Bits R/W Mode Description
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-20h DspSetUp - display setup register
7-5 R/W DspTest - display test mode selection
4 R/W NoRTLmode - disable row-then-line mode
3 R/W UCmode - enable update on change mode
2 R/W JagGrMode - select 95LX-compatible graphics
1 R/W CGAMode - select CGA registers
0 R/W DspEnable - enable MDA/CGA registers and memory
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-21h DspSpd - clock speed selection
3-2 DotClk - dot clock to display module
1-0 DspClk - display DRAM access speed
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-22h 7-0 R/W RowTime - row timer
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-23h 4-0 R/W Contrast - contrast control
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-24h 6-0 R/W HorzDsp - horizontal displayed
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-25h ChrWidth - character width
2 R/W DoubDot - enable dot doubler
1-0 R/W CellWid - character cell width
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-26h 5-0 R/W RowOff - window row size offset
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-27h 4-0 R/W FontOff - font offset
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-28h 7-0 R/W VertDsp - vertical displayed
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-29h 4-0 R/W MaxScan - maximum scan line
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-2Ah 5-0 R/W VertAdj - vertical adjust
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-2Bh 4-0 R/W Underline - underline scan line
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-2Ch ShadeReg - shading and color mapping
3-2 R/W ShadeMode - shading technique selection
1 R/W EnFRS - enable frame-rate shading
0 R/W Invert - invert shades
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