发明名称 |
EXTERNAL INTERFACE CONTROL CIRCUITRY FOR MICROCOMPUTER SYSTEMS |
摘要 |
External interface control circuitry 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. |
申请公布号 |
WO8600154(A1) |
申请公布日期 |
1986.01.03 |
申请号 |
WO1985US01061 |
申请日期 |
1985.06.05 |
申请人 |
MOTOROLA, INC. |
发明人 |
PICKERT, WILLIAM, FREDRICK;PETTINGER, JOSEPH, M.;BIANCALANA, PETER |
分类号 |
G06F1/00;G06F3/00;G06F12/06;G06F13/40;H04L29/00;(IPC1-7):G06F9/00;G06F13/00;G06F7/00 |
主分类号 |
G06F1/00 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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