@ AmigaMance
Thanks for the comment about my screengrabs :pint:
Note that I had used a program called CyberGrab to put a 400K ILBM image in RAM prior to copying it to my Zip 100 to take it elsewhere for conversion to PNG. I would say that the actual amount of chip RAM available before starting any programs would be nearly 800K.
EDIT - With the AmigaOS4 backdrop disabled in WBPattern, this goes up to over 1.2 MB :-)