Boots – shoes – and leggings
Patent
1987-02-04
1988-12-27
Shaw, Gareth D.
Boots, shoes, and leggings
364900, G06F 100, G06F 1130
Patent
active
047945257
ABSTRACT:
External interface control circuitry is described that couples a microcomputer system (100) to an external device (800). The control circuitry includes a microcomputer (102), a power switch (108) for applying power to the external device (800) in response to a PSC* signal, bus control (104) for gating interface signals from the microcomputer (102) with a PD* signal for application to the external device (800) and a peripheral interface adapter (106) for producing the PC and PD* signals and coupling the PI* and READY*/IRQ* signals to the microcomputer (102). A power-up sequence is executed by the microcomputer (102) in response to grounding the PI* signal when the external device (800) is plugged into the microcomputer system (100). Next, the external device (800) produces a binary zero state of the READY*/IRQ* signal, and in response microcomputer (102) produces a binary one state of the PD* signal and thereafter the PC signal. The sequence is then completed when the external device (800) returns the READY*/IRQ* signal to the binary one state. The unique power-up process insures that the external device (800) is only powered when present and protects CMOS devices in the interface control circuitry from being inadvertently destroyed.
REFERENCES:
patent: 4171539 (1979-10-01), Tawfik et al.
patent: 4233666 (1980-11-01), Walberg et al.
patent: 4307455 (1981-12-01), Juhasz et al.
patent: 4312035 (1982-01-01), Greene
patent: 4495568 (1985-01-01), Gilbert et al.
patent: 4593349 (1986-06-01), Chase et al.
Biancalana Peter
Pettinger Joseph M.
Pickert William F.
Eakman Christina
Hackbart Rolland R.
Motorola Inc.
Shaw Gareth D.
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