The Portable StyleWriter, which does not use GrayShare technology like the StyleWriter II, does NOT support grayscale printing and can only produce dithered images. Dithering is the effect of simulating grays or colors by using patterns of black and white dots.
Basically, what you see on the screen on a black & white Macintosh system is what you will get as output on the Portable StyleWriter. Since the Portable StyleWriter does not support grayscale printing, the output will be dithered similarly to the image on the screen.
If the application you are printing from does not support color/grayscale, then the output will not be dithered and will appear as on their Macintoshes screen - purely black and white blotches without dithering.
Support Information Services