Well, you have a 3200x1800 resolution on a 13.3 display.
Normally windows scale everything based on how you set the control panel, but adobe forced Photoshop to ignore that setting.
Pretty reasonable! Without a proper implementation it just "zoom and blur" everything, and since Photoshop is a professional graphic application it cannot blur an image.
So.. if you want to use photoshop 6 you cannot do anything.
Possible solution:
- Use Photoshop Elements instead, it SHOULD scale correctly
- Use Photoshop CC and enable (inside preferences -> experimental features) the 200% zoom.
With that experimental feature you can only zoom by 200% (every pixel become 4 pixels, so no blur) but i think it can work well on your pc.
If you don't see the experimental feature option you are using an old versione of Photoshop CC