High Level Assembler runs under these operating systems. Unless otherwise stated, the assembler also operates under subsequent versions, releases, and modification levels of these systems:

• OS/390® Version 2 Release 10.0 (5647-A01)
• VM/ESA® Version 3 Release 1.0 (5654-A17)
• z/VM® Version 5 Release 2 (5741-A05)
• VSE/ESA Version 2 Release 6 (5690-VSE)
• z/VSE® Version 3 Release 1 andVersion 4 (5686-CF8)
• z/OS Version 1 Release 2.0 (5694-A01)

High Level Assembler supports the operation codes available with the following mode processors:

• Extended Architecture (370-XA)
• Enterprise Systems Architecture/370 (ESA/370)
• Enterprise Systems Architecture/390 (ESA/390)
• z/Architecture