Saturday, July 30, 2022
Tuesday, September 3, 2013
Note: this was written in 2012 and the technical details reflect that time.
As a contractor, you need to keep your skills up, so I kept a lab at home. The clients I dealt with were mostly small and medium sized businesses. SMBs don't generally have large networks and I would often use the lab to try out ideas.
I also liked to browse eBay for cheap gear. If you have looked at the Cisco 1841 router, you would see that many are advertised as having IOS 15, but beware; they often don't have enough memory to run. IOS12 will run on 128MB but IOS15 requires the full 384MB in order to run correctly.
This has happened to me twice now; twice I have purchased 1841's with IOS 15, and twice they have not had the required amount of memory to run IOS 15.
My first 1841 came with IOS12 and 15 so I just dropped back to 12. This is currently my home router. My latest purchase needs to run IOS15 for my lab work, so I decided to try a memory upgrade.
This is the Cisco page showing how to add the additional memory. It is very straight forward requiring only the removal of one screw to get the box open.
Of course you can't just throw any old memory in there. The 1841 comes with either 128MB or 256MB of DRAM, with a single slot for upgrading to 384MB. In my case I have 128MB so I needed a 256MB ram module, and after a little research, This is the one to get.
Installation took maybe all of 5 minutes, and the router is up and running again:
And that is all there is to it. I've been working with the router most of the day, and so far run into no issues with functionality or with the extra memory.
Monday, August 28, 2000
Wednesday, August 10, 1994
Sunday, August 9, 1992
This was one of my first LCD designs. Again I was responsible for the electrical, PCB, LCD and mechanical designs. This was a custom LCD display that was to fit into a plastic molding. The LCD was a separate custom design that I put together including the metal bezel.
The remaining electrical design was conventional surface mount tech, as can be seen in the photos of the completed unit. Some push buttons and LEDs completed the design.
Friday, August 9, 1991
In order to make this stack correctly, the plastic molding had indents and protrusions to ensure alignment. The photo below shows this detail.
Monday, August 6, 1990
I worked at Three Five Systems for five years. I was the only engineer in the UK office and in my time there I did the electronic design, PCB layout and the plastic molding design.
This assembly is the front panel for an industrial controller. It consisted of 6 dual digit displays (14 segments), and a bar graph module. Both of these modules are custom assemblies, so I had three PCBs and two plastic moldings to design.
Thursday, August 17, 1989
Sunday, August 16, 1987
This project was a helmet mounted display for the MBB105 helicopter. The display had some HUD function but was also slaved to the under mounted gun. As the pilot's head moves, so the gun under the helicopter moves with it, and the optical system identifies hard edges of vehicles and buildings for targeting.
Monday, August 10, 1987
The Panavia Tornado was the primary strike aircraft for the royal air force in the 80s. GEC Marconi was tasked with providing an avionics upgrade package that included a partial redesign of the e-scope
Thursday, August 14, 1986
Wednesday, August 6, 1986
Much of my time at GEC Marconi Avionics was spent on the C17 Globemaster project. GEC were putting together an avionics package including the Head Up Display (HUD). HUD systems back then were usually comprised of two parts; the optics assembly, mounted in the pilot's field of view, and the computer system that drives the optics.
Thursday, July 31, 1986
Way back in the 80s I worked for GEC Marconi Avionics. I have no idea why we were asked to do this but we had to design the laser rangefinder receiver for the Abrams tank. Of course in a company that does military work you never get to see the big picture.