SSEM computer used CRT memory (see ssem-mem), so memory cells were actually visible due to phosphorescent electrons glow in the vacuum tube. In emuStudio there are two plugins, separating the functionality of memory and display.
At this link can be seen the original computer.
GUI window of the SSEM display in emuStudio is depicted below:
It doesn’t do any user interaction except displaying. Controlling the memory values can be interactively done in the ssem-mem plugin.