Add-on programs with code verification and control

Details Add-on programs with code verification and control Add-on programs with code verification and control

1979-10-31

1982-03-23

Shaw, Gareth D.

Boots, shoes, and leggings

G06F 1306

Patent

active

043216676

ABSTRACT:
Expandable memory system having add-on modules beginning at fixed address boundaries, e.g., 2K (K=1024), and having verification and authorization features. A non-volatile memory stores a bit corresponding to each 2K memory boundary. When an add-on program is authorized at a particular boundary address, the corresponding bit is set. The base program checks each bit and, if it is set, reads the first location of the corresponding add-on program. If the data read from the new module matches some reference, e.g., the boundary address itself, then program control branches to the add-on program. Additional verification features include cyclic redundancy checks of the added code. Alternative operation includes branching to a verified add-on program that tests its own authorization bit which, if reset, causes a branch to the next verified add-on program, and so on.

REFERENCES:
patent: 3579199 (1971-05-01), Anderson et al.
patent: 3815103 (1974-06-01), Holtey et al.
patent: 3821715 (1974-06-01), Hoff, Jr. et al.
patent: 3838264 (1974-09-01), Maker
patent: 3972028 (1976-07-01), Weber et al.
patent: 4122996 (1978-10-01), Wilczek
patent: 4161277 (1979-07-01), Steiner
patent: 4209846 (1980-06-01), Seppa
Crandall et al., "Dynamic Self--Checking for a Read--Only Storage", IBM Tech. Discl. Bull., vol. 19 No. 8, Jan. 1977, pp. 2868-2869.

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