Type-in from the February 1987 issue of Amstrad Action.
The program is Listed in the video.
From the magazine (courtesy of CPCRulez):
"Richard Turner of Northampton has provided a mini listing that turns a screen upside-down. A simple Call to location &9C40 sets this in motion."
https://dai.ly/x8medli
Best viewed on a large screen at 720p (Dailymotion player setting)
Not emulated - original hardware and software.
Please note that the aspect ratio for this video is 16:9 but the CPC monitor has
an aspect ratio of 4:3 so you may wish to adjust your viewing device accordingly.