Linksys Cisco - 512MB DDR 400MHz PC3200 CL3

As additional software feature enhancements are introduced on the Cisco ASA 5500 Series Adaptive Security Appliances, the minimum memory requirements are changing for the Cisco ASA 5505, ASA 5510,ASA 5520, and ASA 5540 models. These requirements are for software releases starting with the Cisco ASA Software Version 8.3. Cisco ASA appliances running Cisco ASA 8.3 that do not meet the minimum memory requirement are not supported.
Both devices in an ASA failover configuration (active-active and active-standby) must have the same RAM memory. Mixed-RAM devices in ASA failover configurations are not supported.
All Cisco ASA 5505, ASA 5510, ASA 5520, and ASA 5540 appliances will ship with additional default memory to meet the memory requirements for Cisco ASA Software Version 8.3 in February 2010.