Let me add a bit more detail on how this works. The #ibm7094 (specifically the one in the #MIT Computation Center which ran #CTSS) had a hard disk which was used for working storage. My understanding is that the preferred way of working was for users to enter files directly into the system via a teletype terminal, but the system did also have a card reader and multiple magnetic tape drives.

I don't think CTSS provided a friendly way for users to initiate loading from cards (although I'm not sure what there really was in the way of access control for the hardware if you were willing to write your own code). I suspect you wouldn't have had physical access anyway, so you would have had to have worked through the admin staff.

In practice, you would have done this by submitting a job. Jobs covered various I/O tasks, e.g. bulk printing, and for the most part could be submitted through an OS command (which wrote to a special file in the user's home directory). The one exception to this was card input, as that required the physical cards to be submitted to a helpdesk. Those cards were bookended by a metadata card (specifying the user and output filename) at the start and an EOF card at the end. In theory all of the job types could be submitted in the same way - except the 'deck' in those cases would just be the metadata card (and in fact the REQUEST in the users home directory was just an online representation of the same cards).

#retrocomputing #ibm #mainframes

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