Golden Arcade is a real place, and I've described it accurately: there are three malls in one building, winding around each other but unconnected. I need to go back and see if it's still the same! It's a unique place - there are other malls in Hong Kong, in Mong Kok and Wan Chai, but Golden Arcade is special.
I had a favourite shop run by a fantastic businesswoman where I would buy all my parts. She knew from memory what she had in stock and what was compatible.
This is what it looks like from the outside. The only indication that it's there is the green and orange sign on the right that says 'Golden Computer Arcade'. All three malls inside the building have different Chinese names, but they all translate to 'Golden Computer Arcade'. There are also a bunch of shops around the area that have names that translate to 'Golden Computer Shop'.
I stopped and took a photo of the top of the stairs into the cheapest part of the mall, and a shopkeeper ran up and told me off. No photo inside the building, mostly because every single book there is a printed up photocopy of an original textbook. This is the only photo I have of the inside.
Google has a bunch of photos from inside on Google Maps: here's a link if you want to see more of it. https://goo.gl/PYrLa4 - it hasn't changed much since I was there nearly 10 years ago.
I'm hoping (with the help of you Patrons, thank you!) to get back there next year, I'm planning a combined Japan/Hong Kong trip with my daughter. It will be wonderful to revisit my old stomping grounds in Hong Kong, as a completely person to the woman that left there in late 2002.