Hacking HP's OfficeJet 6310
by Daniel Hargett
I wrote this article in 2011, sent it to my English major sister for review, then forgot about it. While the technology mentioned is out of date, it's still not documented anywhere I could find. I think the value in publishing it is that it describes a journey of exploration that solved a problem. I think that is the biggest gift I've gotten from reading 2600 when I was a teenager in the 1990s. It promotes that mindset of "What if I press this button?"
Background
If you're not familiar with HP's business model on HP's InkJet printers, let me run it down for you real quick.
You buy a printer, sometimes for as low as $30 at Walmart, which is probably sold at a loss to HP. They bundle in a set of cartridges and sometimes even some glossy photo paper to show you the awesome capabilities of your shiny new printer. They are so nice! So you print some photos, marvel at the quality, then go buy more glossy paper. Twenty to 30 photos later, you're out of ink! So you go back to Walmart and pay $45 for another set of cartridges! You just paid more for those cartridges than you did for the whole printer! Sometimes a set of cartridges can run as high as $120 depending on what model you have. This can make home printing quite expensive.
In recent years, HP always offers "standard capacity" cartridges and "XL capacity" cartridges. The XL's holding two to three times the amount of ink as the standard cartridges and costing only $5-$10 more. This is an obvious cost-saving choice if you're aware of it. All modern XL cartridges are the same size physically, with walls built into the standard capacity cartridges to make them hold less ink and make it impossible to refill to XL capacity.
Prior to 2005 or so, HP would just release different cartridge numbers that worked in your printer but held more ink. A good example would be the #98 black cartridge (standard capacity) and the #96 cartridge (XL capacity). The unique thing about the #96 is that it is physically larger that the #98. So if HP didn't make the printer internals big enough to hold the #96, then you couldn't even insert it into the printer. They would do this for, say, a $30 printer, so you were forced to buy the smaller capacity cartridges and they profited more than you buying the large cartridges for your cheap little printer.
The Hack
So for reasons out of the scope of this article, I needed to use a #96 cartridge in an HP OfficeJet 6310. This printer is shown as working with only the #98 black cartridge, but if you look inside, there is plenty of room for a #96 to go in. So I put the cartridge in it and the screen told me "The cartridge on right is not intended for this printer."
So even though there is nothing preventing this cartridge from working in this printer, HP artificially limited its use, likely due to the low cost of the printer.
I knew there must be a way around it, so I Googled my question. Hundreds of forum posts popped up with people asking the same question, yet there was not one solution anywhere! Since this was work-related and I didn't know what else to do, I gave up for the time being.
A few days later, I was trying button combinations on the printer control panel in order to print a demo page.
When I pushed * and # together, the screen displayed the following:
This appeared to have made the printer crash or something. When I hit the Cancel button, nothing happened. I unplugged the printer and it restarted and continued to work normally. I tried the * and # again and once more got the strange output on the screen. I am a printer technician by trade and had seen plenty of service menus before. I wondered if this wasn't some sort of hidden service menu.
So in the true hacker spirit, I started pushing buttons. When I keyed in 1 2 3, the screen changed to UNDERWARE: then some letters and characters!
Using the arrow keys showed me more options. I immediately thought of my desire to use the #96 cartridge, but couldn't find any options for cartridges. Hitting the Cancel button enough times took me back to the normal screen. I then hit * and # and began trying all different number combinations and searching the menus that came up.
The combinations that yielded menus are as follows:
I hit pay dirt on the 1 2 7 menu.
There is a menu option that says Set boot code to MFG then you press OK and the boot code is set to manufacturer mode.
I power-cycled the printer and, when it came back on, it flashed MFG Mode during startup. I inserted the #96 cartridge and it worked without a hitch! Now keep in mind that I do not have this printer connected to a computer. I don't know if it will affect printing when connected to a computer.
I just use it to test refilled cartridges. It will print all reports and make copies though. It will print all reports and make copies though. There is also an option to Set boot code to user to undo this.
I have tried the * and # on many HP InkJets since then and it always works.
The screen usually says Enter Special Code when you hit them though. It has worked on many OfficeJet models and PhotoSmart models with fax capabilities. I even found it on a low-end PhotoSmart that didn't have a keypad! Some printers have very useful diagnostic tests hidden in these menus. Most have undecipherable options though.
I don't know what most of these functions do, but it provides a huge new playground for curious hackers to explore!