Falkirk Sheriff Court was told that police seized nine devices – computers, phones, digital cameras, a USB stick and external drives – and child abuse material was found on all of them.
Five of the devices were subjected to a full examination.
The court heard previously that almost 1.4 million images remained ungraded on one of the devices, due to the extent of the collection.
MacPherson was caught after police identified his IP address was being used to distribute child abuse material.
Prosecutor Rachel Wallace said that in July 2025, MacPherson posted multiple images of child sexual exploitation, classed as the most serious, during an online chat with an undercover police officer.
Although he was using a messaging app designed to be anonymous, police were able to trace the messages to his home.
The child victims were girls, mostly aged between nine and 15, but at least one was possibly as young as seven.
Wallace said: “Police have advised us this is quite possibly the largest collection of child sexual abuse material ever seen by Police Scotland.”
When MacPherson was arrested and interviewed, he told police he had searched online for years for indecent images of children “for his own personal gratification”.