HP printers print B&W with just the black cartridge used
Black blacks, and looks as good as any B&W darkroom print, though not a glossy as using a glazing sheet.
Resolution is 600DPI, though as with all inkjets, the actual resolution on the final print depends on the paper, too absorbent or too glossy both make the "dots" bigger or smudged when looking with a loupe / magnifying glass.
With the eye, they look very sharp, but not as sharp as I have seen from professional printers. Like anything, you get what you pay for.
Ink for HP is inexpensive, less than 5p a page.