Revision as of 11:02, 18 June 2024 view source Retroand (talk \| contribs) Bureaucrats, Interface administrators, Administrators 666 edits →‎Gallery ← Older edit		Revision as of 11:04, 18 June 2024 view source Retroand (talk \| contribs) Bureaucrats, Interface administrators, Administrators 666 edits m →‎ROM Operating System: Corrected typo Tag: Visual edit Newer edit →
Line 70: \|} [[File:ROS Memories.jpg\|thumb\|left\|alt=Some of the sixteen ROS memories\|Some of the sixteen ROS memories]] The ROM Operating System or ~~symply~~simply ROS is the firmware of the System/23. It consists in a set of sixteen ROMs of 8KB each, for a total of 128KB. Each ROS ROM has a unique diagnostics identification code, which is determined by the outputs of two 74LS138 3:8 decoders. ROMs 02h and 09h are fixed in the memory map, where the rest are paged in the memory range 4000h-7FFFh. ROMs 0Eh and 0Fh are not present but the logic to select them is implemented even if there is no place to place them in the board; still, with an appropriate ROM adapter their space could be enabled to inject code into the system. ROMs paged 0-7 are present in the board while ROMs paged 8-15 are expected to be provided by expansion cards on their corresponding slots. Therefore, the maximum theoretical ROM capacity for the Datamaster consists of 272KB if the 0Eh-0Fh gap and pages 8-15 are used.

IBM System/23 Datamaster: Difference between revisions