Feeding Dinosaurs: Keeping Ancient HP LaserJets alive
The world’s first laser printer was built by Gary Starkweather at Xerox PARC in 1971, hooking up a Xerox photocopier and an early Xerox computer. The first commercial laser printers were huge data-center-scale monsters, the IBM 3800 and the Xerox 9700. It took most of a decade, and the crossover from cameras to computers by Canon, for the laser printer to become affordable for home and small business users. Canon invented a desktop-sized print engine and sold it to Apple and HP. The rest, as they say, is history. HP has become the dominant seller of laser (and inkjet) printers; here is a retrospective on their continuous introduction of new models and features.
Inkjet printers are cheaper to buy, but generally more expensive to feed ink into. Indeed, for a while, these printers were almost free, but the ink was costly. Manufacturers resorted to various “copy protection” techniques to prevent third-party suppliers from producing ink. Laser printers cost more to buy, but have advantages in addition to cost: they are faster, and, you can leave them idle for months (or even years) without the ink drying out (since their ink, called “toner”, is already a dry powder). So you don’t have to trash your old printer and buy a new one every couple of years.
The HP laser printers made from about 1980 to about 2000 have a reputation for long-lasting reliability. Indeed, we have an HP LaserJet 6MP which we bought new around 1997(!). It was in steady use for a couple of decades as our family’s printer. But that’s not the end of the story.
Most printers today can communicate with a computer over the industry-standard USB protocol. Earlier laser printers used a “Centronics” or “parallel” connector inherited from older dot-matrix printers, of which Centronics was a major manufacturer. The cable had a 25 pin connector at one end, a cable with 25 separate wires inside it, and a 36-pin connector at the other. The HP6MP has two different connectors for the once-common “PC Parallel Port” and one for the now-legacy AppleTalk network, but does not have standard Ethernet connectivity. As the years rolled by and PCs and laptops lost their parallel ports, our 6MP was sidelined for a while and we used other printers. It went back into service when my HP laptop acquired an old docking station with a parallel port. I just blew the dust off the printer, plugged it in, and it literally started printing right away. When that laptop was replaced by a sustainability-oriented Framework Laptop, the 6MP was again down for a while. But only a few weeks this time.
I found a seller on eBay who had a JetDirect 300X print server. A “print server” is a dedicated tiny computer to which computers can send print jobs using a variety of network protocols over TCP/IP on a standard Ethernet “blue cable” (newer print servers use WiFi). And the 300X talks to the printer via the old standard parallel printer cable connection. Soon the 6MP was back to work, and in fact is now reachable from multiple computers at the house. And this ole’ HP just keeps printing!
My cheapo JetDirect 300X came loaded with extremely old firmware (not surprising given how old the design is). I was able to download a 2017 update from HP, but the directions to install it didn’t work because the firmware in the unit was too old. Fortunately an enthusiast with a similar problem had been able to piece together a solution which worked (I mostly followed the directions there, but used OpenBSD Unix with its working built-in tftp server, instead of Linux). I said “fortunately” because one of the fixes in the newer firmware was for this major security flaw that affected almost all networked HP printers.
Most early LaserJets offered memory expansion (RAM) through a kind of interchangeable memory called a SIMM (Single In-line Memory Module). These had 72 pins to connect to the computer’s memory socket. Most of today’s computers use DIMMs, and laptops use SODIMMs (both of which have around 200 pins to connect to the computer, since they have a much larger memory range and more capabilities). In the era when we bought the HP6MP, memory was quite expensive compared to today, so the unit came with a whopping 3 megabytes of SODIMM RAM (actually I think I upgraded it to that 3MB a few years after buying it). You’d think “nobody makes megabyte memory these days, it’s all gigabytes”, and you’d be right. Almost. However, you can still buy new memory SIMMs specifically for HP printers, and from several sources at that. The HP SIMMs have a slight (and pioneering, for its day) modification from then-standard SIMMS, to tell the printer how much memory is on the card. For the avid electronics do-it-yourselfer, you can scrounge industry-standard 72 pin SIMMs (from an ancient PC, perhaps) and modify them by soldering jumper wires onto the SIMM to “sim”ulate HP’s size-detection configuration. I think I’ll just buy some new memory with the jumpers already on, instead of dusting off my soldering iron.
How long will our 6MP keep working? Nobody can say. As long as we can buy toner for it, and it doesn’t lay down and return to the primordial ooze, I’ll keep feeding the dinosaur.
