[mark-r]

I once worked at a company that used a Code39 font cartridge in HP Laserjets. When HP stopped putting font cartridge slots in their printers, I had the task of intercepting print jobs and detecting the font selection sequence, then taking the text and converting it to a Code128 bitmap graphic. It wasn't hard at all, kind of fun actually.

[darksim905]

'font' cartridge? the what now?

[EvanAnderson]

You're one of today's lucky 10,000.

Like another poster said, laser printers "back in the day" were freestanding computers with various communications interfaces that happened to have fancy paper handling and printing peripherals attached. In the case of the Apple LaserWriter, for example, it was arguably a more powerful computer[0] than the Mac machines of the day that were sending print jobs to it.

There were different ROM "personalities" available for laser printers, some of which came on pluggable cartridges.

Check these links out:

- https://www.pagetable.com/?p=1673

- https://www.pagetable.com/?p=1721

- https://www.pagetable.com/?p=1850

Michael Steil, the blogger responsible for those links, has done work extracting code and PostScript data out of some of those old cartridges. It's a really cool aspect of retrocomputing many people aren't even aware of.

[0] https://web.archive.org/web/20240404213221/https://lowendmac...

[darksim905]

commented elsewhere but The links you shared are pretty cool, a little before my time (born late 80s). That's kinda neat, it makes me think of a post on HN some time back by Donald Knuth on the letter S and the technical challenges back then about that as a letter, mathmatically. I'm guessing given that, that's why printers needed these modules and were set up this way. Neat!

[mark-r]

The LaserWriter was like something from the future compared to the Laserjet. I think they used the same Canon print engine, but the HP was far less sophisticated. It only used bitmap fonts, nothing scalable like Adobe's Type 1 for Postscript. Knuth probably used a supercomputer for his typesetting.

[mark-r]

And if you don't know the origin of the phrase "lucky 10,000" then it's your lucky day too!

https://xkcd.com/1053/

[ValdikSS]

In the dark ages, when printers were PostScript and more powerful (and expensive) than the computers which printed on them, you added fonts by installing additional hardware modules, similar to a game console cartridge.

[darksim905]

The links someone else shared are pretty cool, a little before my time (born late 80s). That's kinda neat, it makes me think of a post on HN some time back by Donald Knuth on the letter S and the technical challenges back then about that as a letter, mathmatically. I'm guessing given that, that's why printers needed these modules and were set up this way. Neat!

[xp84]

Up until like 15 years ago, lots of laser printers even had RAM slots as well. Populating them with extra RAM made them behave better when printing big PDFs and stuff.

[benj111]

Don't say it too loudly. I'm sure HP would love to introduce 'Font as a service'

[wildzzz]

They were ROM cards that stored extra typefaces or other PostScript functions.