Ever since I started up this company I've been too tight to buy a new laser printer - and I haven't needed to as I was donated a LaserWriter 12/640PS printer and seven toner cartridges back in 2001. I have this printer sitting on my LAN with Apple and Windows machines accessing it. I've found it to be a good workhorse but a bit slow, especially if sending a graphic or a .pdf to print.
In order to try and speed things up a bit I decided to look into upgrading the memory. This won't make it print more pages per minute and it won't improve communication speed over the LAN but it will allow more room for fonts and graphics when I send jobs to print.
In order to get into the unit, remove the two screws from the rear (on the right hand side when facing the rear above and below the communication ports). Remove the paper tray and you should find the front side held on by a plastic retaining tag - unclip it. With a careful bit of pulling the side panel should come away (try pulling from the top).
Removing the side panel
Removal of the side panel will reveal the logic board as shown below. There are two memory slots and base specification models (such as mine) are fitted with a single 4MB SIMM (the thing with the orange label towards the centre of the picture below).
This printer takes 72 pin SIMMS and can be fitted with a maximum of 64MB. It can also take mixed sizes of memory. I had a spare 16MB SIMM so I fitted it with the existing 4MB SIMM to make 20MB total. I've certainly noticed the difference especially when printing graphics.