So I was able to get my hands on a Cisco 2621 with a decently sized flash. I found out the hard way that some of these older routers have tiny flash memory drives that are too small to load any decent ios images on. Plus I found that in order to upgrade the flash memory, you also had to upgrade the bootrom. This chip and dimm combo runs about $30-$40. I was able to pick up this 2621 with 32mb flash (vs 8mb of my other 2621).
So lets get the device up and running by resetting it to factory defaults.In order to accomplish this you need to boot to the rommon, which is accomplished by hitting the break sequence during the boot up process (specifically within 60 seconds).
In minicom you accomplish this with the following key strokes.
You will then see the following screen
rommon 1 >
Type the following to bypass startup files durring the boot process.
rommon 1 > confreg 0x2142
You will see the following message.
You must reset or power cycle for new config to take effect
Now do what it says, and type reset as show below.
rommon 2 > reset
The router will reboot and you will be prompted to enter the initial configuration dialog, choose no to this option.
Now overwrite the saved config on the router with the command below.
Then run the following command so that at next boot you are not bypassing the startup files.
Now restart the router again and and the config will be wiped and passwords reset.
Click here for the Cisco article that I used for reference.