For MG1,MG2,MG4,MG8 file have HEADER 256 bytes length
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[3] MGx_FILE_ID Identifier for MG files = "MGH" (Milti Gigascreen ZX File Header)
[1] MGx_FILE_VER MG zx file format Version
[1] MGS_CharSize Size of Char[1=8x1, 2=8x2, 4=8x4, 8=8x8]
[1] ZX Color1 Border
[1] ZX Color2 Border
Data Format *.MG2
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[6144] BitPlane0 Interlaced Bit Data (ZX original screen bitplan)
[6144] BitPlane1 Interlaced Bit Data (ZX original screen bitplan)
[3072] MGSAttr0 Linear MultiGigaScreen ATTR Data
[3072] MGSAttr1 Linear MultiGigaScreen ATTR Data