Debug device
From MSX Game Library
Proposal to improve the debugging protocol used by openMSX pseudo-device.
Based on: https://openmsx.org/manual/user.html#debugdevice
Improvement
In Multi-byte mode, use the two remaining bits for: bits #2: 0=8 bits number; 1=16 bits number (requires 2 consecutive outputs to 2Fh port) bits #3: 0=unsigned, 1=signed (needed for decimal display)
Bit #7 can also be used: 0=Output 1=Special (for the moment, have a break with FFh)