I have a code listing for the 8048, from about 1977. It's printed in a databook, in dot-matrix format. I don't know how well it will scan. That's not a safe presumption at all. What you need is the datasheet for the printer mechanism. It probably has a part number. How do you know that? Those are commonly called "print resistors" and behave not unlike diodes. You'll probably find there are series resistors, too.

You probably need to know just when to latch the data and how to clock the thing, too. Also, if there are shift registers, there will be timing issues. A schematic with signal definitions will prove useful.

You've got your work, and plenty of it, cut out for you, Collin, but you can do this. These things work on the basis that the print resistor array stays stationary (some move, of course, and you haven't clarified that.) and the paper moves, with the print resistors firing at the appropriate time to discolor the paper. Usually a stepping motor, but sometimes a DC type, drives the paper feed. You'll use up a lot of paper figuring out just how long to fire the resistors, and, BTW, once one of them fails, the whole array is junk, so be careful with the drive current. Normally, they're driven with low-side switches. If you think about how that resistor array has to work, you'll see how a shift register could come into play. If it really does use shift registers, there are probably decoder/drivers, and counters, too, and it's likely the paper is driven with a stepper. It could be a DC type, though, but if you have a sample of its printing, you can see that because there'll be a slight vertical offset between dots in a row. The columns should all be aligned.

Take a closer look. Search for a part number, and then, a datasheet. That'll help a lot more than I can.

RE