BENTLY 330103-00-03-05-02-05线缆软件初始化开关或跳线打开时启用的大多数功能其他模块通过在上设置控制寄存器来启用MVME177。在通电或重置时，包含177Bug调试包设置了许多这些寄存器。具体的编程细节可以通过研究M68060微处理器用户手册。您也可以查看详细信息单板中给出的所有MVME177板载寄存器计算机程序员参考指南。

BENTLY 330103-00-03-05-02-05线缆多微处理器编程注意事项良好的编程实践要求一次只能使用一个MPU控制MVME177控制寄存器。特别值得注意的是：❏ 修改地址映射的寄存器❏ 需要两个周期才能访问的寄存器❏ VMEbus中断请求寄存器本地重置操作本地重置（LRST）是系统重置（SRST）的子集。本地重置can可通过五种方式生成：❏ 看门狗计时器过期❏ 按下前面板重置开关（如果系统控制器功能已禁用）❏ 在GCSR中的板控制寄存器中断言位❏ 系统重置*❏ 通电复位注：GCSR允许VMEbus主机重置本地公共汽车此功能非常危险，应使用小心。局部重置功能是一个局部系统重置，而不是完整的系统重置，如通电重置或系统重置*。当本地总线重置信号为断言，本地总线循环可能会中止。这个VMEchip2连接到本地总线和VMEbus和中止的循环是否为VMEbus，可能会导致不稳定的操作。本地处理器和VMEbus主机应使用中断或邮箱位置；正常情况下不应使用重置通信。只有当本地处理器停止或本地总线挂起重置是最后的手段。当MVME177处于重置状态时，对其的任何VMEbus访问都是忽略。如果启用了全局总线计时器，则会生成总线错误。

Software Initialization

Most functions that have been enabled with switches or jumpers on

other modules are enabled by setting control registers on the

MVME177. At power up or reset, the EPROMs that contain the

177Bug debugging package set up the default values of many of

these registers.

Specific programming details may be determined by study of the

M68060 Microprocessor User's Manual. You can also check the details

of all the MVME177 onboard registers as given in the Single Board

Computers Programmer's Reference Guide.

Multi-MPU Programming Considerations

Good programming practice dictates that only one MPU at a time

has control of the MVME177 control registers.

Of particular note are:

❏ Registers that modify the address map

❏ Registers that require two cycles to access

❏ VMEbus interrupt request registers

Local Reset Operation

Local reset (LRST) is a subset of system reset (SRST). Local reset can

be generated five ways:

❏ Expiration of the watchdog timer❏ Pressing the front panel RESET switch (if the system

controller function is disabled)

❏ Asserting a bit in the board control register in the GCSR

❏ SYSRESET*

❏ Power-up reset

Note The GCSR allows a VMEbus master to reset the local

bus. This feature is very dangerous and should be used

with caution. The local reset feature is a partial system

reset, not a complete system reset such as power-up

reset or SYSRESET*. When the local bus reset signal is

asserted, a local bus cycle may be aborted. The

VMEchip2 is connected to both the local bus and the

VMEbus and if the aborted cycle is bound for the

VMEbus, erratic operation may result.

Communications between the local processor and a

VMEbus master should use interrupts or mailbox

locations; reset should not be used in normal

communications. Reset should be used only when the

local processor is halted or the local bus is hung and

reset is the last resort.

Any VMEbus access to the MVME177 while it is in the reset state is

ignored. If a global bus timer is enabled, a bus error is generated.