SYS1/zip     Source for System 1 Monitor
SYSMON1      System 1 Monitor
SYS2/zip     Recreated source for System 2 COS/Kernel
SYSCOS40     System Kernel, 40-column text, Cassette OS, 6845-R or S
SYSCOS40s    System Kernel, 40-column text, Cassette OS, 6845-S, teletext characters translated
SYSCOS80     System Kernel, 80-column text, Cassette OS, 6845-S