Method for autonomously transferring code to a computer without accessing local memory by the central processing unit

Abstract

Abstract In a computer-driven device, a start-up mode after reset is provided whereby boot-up instructions are by default always accepted directly from an external source. The device may comprise a gate array (GA) which is connected directly via a serial port to a receiving or input device, to receive program code for transfer directly as instructions to a microprocessor-type central processing unit. The central processing unit is part of a computer controlled device containing a microprocessor, memory (a RAM), and typically a bulk erase flash memory device, the flash memory device being unprogrammed when the computer controlled device is fabricated originally. When the computer controlled device first powers up, a special mode of operation ensues in which the gate array directly monitor bits received via the serial port from the input device and shifts them into a local register from which bytes or words are loaded directly into the CPU as instructions. A boot sequence is thereby accepted in this manner to load random access memory of the free-running CPU which thereafter can control transfer of additional executable code or load a permanent boot sequence into bulk erase (nonvolatile) flash memory. The invention can be incorporated into a wireless modem/packet terminal node controller. The input device may be a coupling to an external computer system, typically a serial input.

Inventors

• 👤 David L. Paulsen

Bibliographic Details