More options: (read/write DCO6, read DCS6)
0001 enable video screen swapping
0002 keep video screen when disabling swapping
0010 read key from interrupt 16h when swapping (V command)
0200 use ROM-BIOS output even when DOS available
0400 load and write .EXE and .COM files like flat .BIN files (/F+)
0800 for loading flat .BIN files set up Stack Segment != PSP (/E+)
1000 enable 40-column friendly mode
2000 in 40-column mode indent odd D lines more
4000 in 40-column mode display dashes at half of D length
01_0000 allow to share serial IRQ handler
0100_0000 use ROM-BIOS I/O even when DOS available (disables script file read)
2000_0000 display flags in style 2 for R command register dump
4000_0000 display flags in style 3 for R command register dump
8000_0000 linebreak before R register dump if not column 0 (int 10h only)
