Labels: text | drawing | map | diagram OCR: Barrel Shifter Function Start Address GR3, 63,4 CRTC reg C&D - CPU Write msb CPU Read CPU Write Data 00-7 ALU 1sb I N/A-O None, AND OR, XOR Bit Mask Display Q GR8 Memory Latch Data Rotate GR3, 60-3 Address * Set/Reset 0 GRO, 60-3 8 Enable Set/Reset 0 GR1, 60-3 8 8 Write Mode + CPU Read GR5, 60,1 Plane 1 Latch- Data DO-7 EGA Functional Diagram Plane 2 Latch by Bob Montgomery Orlando, Florida Plane 3 Latch 12-1-87 * Color Compare @ 8 8 GR2, 60-3 8 * Color Don't Care 0% GR7, 60-3 Data from Plane 1 Read Map - 100 00 *= >Extend bit to byte. Data from Plane GR4, 60-2 Data from Plane 3 Read Mode GR=Graphics Register (3CE, 3CF). GR5, 63 Read Map=n selects plane n for reading. Each bit gated Color Don't Care bit n=0 makes color compare ignore plane n. Bit Mask passes Latch data where bits are 0, and switch data where bits are 1.
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