PDP11GUI Bitfields window
Often a peripheral register does not contain a single scalar 16 bit value, but is segmented into different bit groups. Every group of bits represents a “sub-value”, so one memory address contains several information fields. The Bitfields window shows and edits those bitgroups.
Whenever you click on a memory address in the Register or the Memory window, the Bitfield window is synchronized to show the bit fields of the selected address.
In the example, I clicked on the PSW in the “CPU register” window. Then I manually edited the “Z”-flag in the bitfield window to “1”. Since I did not yet pressed “Deposit”, the changed bit is marked yellow. In field “value” the final 16-bit is updated to “00345” and also marked in yellow.
The bitfield information for register addresses is defined in the machine description file.