Motorola MVME166IG/D2 - Manual (Page 59)

Memory Requirements
MVME166IG/D2 3-13
3
❏ confidence test failure
❏ NVRAM checksum error
❏ NVRAM low battery condition
❏ local memory configuration status
❏ self test (if system mode) has completed with error
❏ MPU clock speed calculation failure
After debugger initialization is done and none of the above situations have
occurred, the SYSFAIL* line is negated. This indicates to the user or VMEbus
masters the state of the debugger. In a multi-computer configuration, other
VMEbus masters could view the pertinent control and status registers to
determine which CPU is asserting SYSFAIL*. SYSFAIL* assertion/negation is
also affected by the ENV command. Refer to Appendix A.
MPU Clock Speed Calculation
The clock speed of the microprocessor is calculated and checked against a user
definable parameter housed in NVRAM (refer to the CNFG command in
Appendix A). If the check fails, a warning message is displayed. The
calculated clock speed is also checked against known clock speeds and
tolerances.
Memory Requirements
The program portion of 166Bug is approximately 512KB of code, consisting of
download, debugger, and diagnostic packages and contained entirely in Flash.
The Flash memory on the MVME166 is mapped starting at location $FF800000.
166Bug requires a minimum of 64KB of contiguous read/write memory to
operate.
The ENV command controls where this block of memory is located.
Regardless of where the onboard RAM is located, the first 64KB is used for
166Bug stack and static variable space and the rest is reserved as user space.
Whenever the MVME166 is reset, the target PC is initialized to the address
corresponding to the beginning of the user space, and the target stack pointers
are initialized to addresses within the user space, with the target Interrupt
Stack Pointer (ISP) set to the top of the user space.
At power up or reset, all 8KB of memory at addresses $FFE0C000 through
$FFE0DFFF is completely changed by the 166Bug initial stack.