An Input/Output Architecture for Virtual Memory Computer Systems
Abstract
In many large systems, user I/O must be performed for the user by the system, in order to assure such system goals as security, response, and efficiency. However, reduced overhead and increased flexibility would result if the user could perform his I/O directly. This thesis presents a design for an I/O subsystem architecture which, in the context of a segmented, paged, time- shared computer system, allows the user direct access to I/O devices. Some conclusions of this thesis are: (1) that in order to provide a coherent program structure, I/O operations should be contained in a separate I/O process, (2) that to allow the user to refer to his devices in a simple fashion while protecting his devices from other users, the I/O device should be represented to the user as a segment, (3) that the virtual memory can meet the timing needs of the I/O system without compromising its own functions by the use of time limits on the duration of the I/O operations, and (4) that interrupts should not be part of the user environment, but should be hidden from the programmer, so that the I/O program he constructs is sequential rather than interrupt driven in structure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1974
- Accession Number
- AD0774738
Entities
People
- David D. Clark
Organizations
- Massachusetts Institute of Technology