I'm getting a "79.01" error message on an HP Laserjet 8150N printer
and want to do a firmware upgrade to it.

Am looking for instructions on how to do the firmware upgrade.

Thanks.

Hello Skip9801l,

As you correctly surmised the error 79 may indicated a firmware
problem.  There are a number of other possibilities though, so you may
want to try troubleshooting those first.  HP has a support page here
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?locale=en_US&taskId=110&prodSeriesId=27718&prodTypeId=18972&objectID=c00033428
that offers a step by step troubleshooting procedure for errors 49 and
79.

Assuming you've done all that and you still need to upgrade the
firmware you need to get the appropriate firmware installation file. 
The download page for the various firmware versions (Mac, PC, Unix) is
here: http://h20000.www2.hp.com/bizsupport/TechSupport/DriverDownload.jsp?locale=en_US&pnameOID=21694&taskId=135&prodTypeId=18972&prodSeriesId=27718&submit.y=7&submit.x=6&lang=en&cc=us&swEnvOID=54

Instructions for installation are also provided by HP in the readme
file that accompanies the firmware.  I don't know your operating
system or your setup so I won't summarize the file, but the
instructions are pretty straightforward.  The readme file is here:
http://ftp.hp.com/pub/printers/software/lj8150lbreadmefw.txt

I hope this solves your printing woes.

Hibiscus