More options: (read/write DCO2, read DCS2)
0001 DB: show header
0002 DB: show trailer
0010 DW: show header
0020 DW: show trailer
0100 DD: show header
0200 DD: show trailer
0800 use getinput function for int 21h interactive input in DPMI
1000 H: stay compatible to MS-DOS Debug
2000 idle and check for Ctrl-C in getc
4000 idle and check for Ctrl-C in getc in DPMI
8000 T/TP/P/G: cancel run after RE command buffer execution
01_0000 N: operate in MS Debug style instead of K command alike
02_0000 N: capitalise command line tail
04_0000 explicit 0-length ranges operate in partial MS Debug style
08_0000 R: 16-bit 80-column register dump in MS Debug style
10_0000 R: do variable prompts in MS Debug style
20_0000 R: do variable prompts with underscore separator
40_0000 display linebreak before R command register dump
