公开(公告)号：US5392441A

公开(公告)日：1995-02-21

申请号：US143529

申请日：1993-10-26

申请人： Gary L. Brasher ,  James H. Nuckols ,  Jeffrey S. Watters

发明人： Gary L. Brasher ,  James H. Nuckols ,  Jeffrey S. Watters

IPC分类号： G06F13/40 ,  G06F13/42 ,  G06F13/00

CPC分类号： G06F13/4072 ,  G06F13/4217

摘要： A data field having a variable number of zero-level bits is read by a bus in a digital system, wherein the bus is pumped by writing all logical "one" bits onto the bus lines just before they are read. The unused bits will then be still in a logical "one" state, i.e. a known value, rather than floating or at an indeterminate value. A program for performing this operation in a computer uses steps to prevent other operations such as refresh cycles or interrupts from being interposed between the write and read cycles. A CPU may use this method to read a system identifier value upon boot-up, for example.

摘要翻译： 具有可变数量的零电平位的数据字段由数字系统中的总线读取，其中通过在读取总线之前将所有逻辑“1”位写入总线来泵送总线。 然后，未使用的位将仍然处于逻辑“一”状态，即已知值，而不是浮动或不确定值。 用于在计算机中执行该操作的程序使用步骤来防止诸如刷新周期或中断之类的其他操作被插入在写周期和读周期之间。 例如，CPU可以使用该方法在启动时读取系统标识符值。

公开(公告)号：US4959860A

公开(公告)日：1990-09-25

申请号：US307402

申请日：1989-02-07

申请人： Jeffrey S. Watters ,  Norman P. Brown ,  James H. Nuckols

发明人： Jeffrey S. Watters ,  Norman P. Brown ,  James H. Nuckols

IPC分类号： G06F21/00

CPC分类号： G06F21/79

摘要： A power-on password security function for a digital computer system allows the system software to distinguish between authorized and unauthorized users. Safeguards are made against corruption of password data which could lead to lock-out authorized users, and redundant checks allow the security function to operate even when first-level checks fail. The battery-powered RAM storage area used to hold the password when the system is turned "off" is protected against being accessible by unauthorized users when the system is turned "on".

公开(公告)号：US06182187B2

公开(公告)日：2001-01-30

申请号：US08044241

申请日：1993-04-07

申请人： B. Tod Cox ,  Peter J. Michels ,  Michael R. Kluth ,  Jeffrey S. Watters

发明人： B. Tod Cox ,  Peter J. Michels ,  Michael R. Kluth ,  Jeffrey S. Watters

IPC分类号： G06F1200

CPC分类号： G06F9/4403

摘要： A computer system having a system ROM comprising a flash or bulk EPROM replacing a block flash or boot block EPROM, and a second ROM to store the primary boot code. In a first embodiment, a single block EPROM is replaced with a bulk EPROM and a ROM, where the ROM is preferably a one-time programmable ROM. The primary boot code is copied into the ROM thereby preventing its erasure. The bulk EPROM is reprogrammed if desired. Separate decode logic detects an address to the primary boot code and enables the ROM. In a second system using a block EPROM and a bulk EPROM as the system ROM, the block EPROM is replaced with a bulk EPROM, and the primary boot code is copied into both bulk EPROMs, preferably at mirrored locations. An external switch is provided with appropriate logic, so that the user may select between either of the bulk EPROMs to boot the system. Thus, if the system is unable to boot from one of the bulk EPROMs, the user may flip the switch to access the primary boot code from the other bulk EPROM. A software program is executed after successful reboot to reprogram and verify the contents of both of the bulk EPROMs. The software reprograms and verifies one bulk EPROM and then reprograms and verifies the other to assure data integrity.

摘要翻译： 一种具有系统ROM的计算机系统，该系统ROM包括代替块闪存或引导块EPROM的闪存或大容量EPROM，以及存储主引导代码的第二ROM。 在第一实施例中，单块EPROM被大容量EPROM和ROM替代，其中ROM优选地是一次性可编程ROM。 主引导代码被复制到ROM中，从而防止其擦除。 如果需要，大容量EPROM被重新编程。 单独的解码逻辑检测到主引导代码的地址，并启用ROM。 在使用块EPROM和批量EPROM作为系统ROM的第二系统中，块EPROM被大容量EPROM替换，并且主引导代码被复制到两个批量EPROM中，优选地在镜像位置。 外部开关具有适当的逻辑，使得用户可以在任何一个批量EPROM之间选择引导系统。 因此，如果系统不能从大容量EPROM之一引导，则用户可以翻转开关以从另一个批量EPROM访问主引导代码。 成功重新启动后，执行软件程序重新编程和验证两个批量EPROM的内容。 软件重新编码并验证一个批量EPROM，然后重新编码并验证另一个批量EPROM，以确保数据完整性。