An AS/400 programmer is responsible for the development and maintenance of computer software based on the IBM operating system. Your duties and responsibilities in this career include programming and testing code for applications and software, either independently or for a company. You may also create Software-as-a-service (SaaS) applications. If you work as an in-house programmer for a company, you can either work alone or as part of a team, so depending on the position, communication skills may be crucial. The AS/400 programmer career field also has opportunities for remote work.