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Remote file access over low-speed lines

Hague, James Mortimer (1988) Remote file access over low-speed lines. Doctor of Philosophy (PhD) thesis, University of Kent. (doi:10.22024/UniKent/01.02.94392) (KAR id:94392)


A link between microcomputer and mainframe can be useful in several ways, even when, as is usually the case, the link is only a normal terminal line. One interesting example is the ‘Integrated application’, which divides a task between microcomputer and mainframe and can offer several benefits; in particular, reducing load on the mainframe and permitting a more advanced user interface than possible on a conventional terminal.

Because integrated applications consist of two co-operating programs, they are much more difficult to construct than a single program. It would be much easier to implement integrated applications concerned with the display and/or modification of data in mainframe files if the microcomputer could confine its dealings with the mainframe to a suitable file server. However, file servers do not appear practical for use over slow (compared to disc access speed) terminal lines.

It was proposed to alleviate the problems caused by the slow link with extended file operations, which would allow time-consuming file operations such as searching or copying between files to be done in the file server. It was discovered after attempting such a system that extended file operations are not, by themselves, sufficient; but, allied to a record-based file model and asynchronous operations (i.e. file operations that do not suspend the user program until they complete), useful results could be obtained.

This thesis describes FLAP, a file server for use over terminal lines which incorporates these ideas, and MMMS, an inter-application transport protocol used by FLAP for communication between the microcomputer file interface and the mainframe server.

Two simple FLAP applications are presented, a customer records maintenance program and a screen editor. Details are given of their construction and response time in use at various line speeds.

Item Type: Thesis (Doctor of Philosophy (PhD))
DOI/Identification number: 10.22024/UniKent/01.02.94392
Additional information: This thesis has been digitised by EThOS, the British Library digitisation service, for purposes of preservation and dissemination. It was uploaded to KAR on 25 April 2022 in order to hold its content and record within University of Kent systems. It is available Open Access using a Creative Commons Attribution, Non-commercial, No Derivatives ( licence so that the thesis and its author, can benefit from opportunities for increased readership and citation. This was done in line with University of Kent policies ( If you feel that your rights are compromised by open access to this thesis, or if you would like more information about its availability, please contact us at and we will seriously consider your claim under the terms of our Take-Down Policy (
Uncontrolled keywords: Microcomputer/mainframe link
Subjects: Q Science > QA Mathematics (inc Computing science) > QA 76 Software, computer programming,
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Computing
SWORD Depositor: SWORD Copy
Depositing User: SWORD Copy
Date Deposited: 13 Jul 2023 10:58 UTC
Last Modified: 13 Jul 2023 10:59 UTC
Resource URI: (The current URI for this page, for reference purposes)

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