the timer. If the timer overflows, the VOID_TIMER_OVF bit in the INTR_EVENT_C
register will be set. This indicates that the ring may have latency problems.
3.7 INTERNAL REGISTERS
Four registers are not normally of interest to the NP, although they all can be read at any
time However, it can take more than one read operation to obtain their value and they can
change value between these reads. They are exclusively used for ATE testing and
diagnostic software. None of these registers can be directly written by the NP. These
registers are not further defined for user operation.
3.7.1 Revision Number Register (REV_NO_REG)
MAC CHIP TYPE (LSB)
This register contains the MAC chip type and revision number.
MAC Chip Type for a standalone chip is 00000000.
MAC Revision Number. This is 0000 for MAC Rev A and 0011 for MAC Rev C.
3.7.2 Packet Request Register (PKT_REQUEST)
The packet request register is intended for factory testing only to allow test programs to
access the internal packet request state. This register contains the last, or current, packet
request header control bytes presented to the MAC by the FSI. See 8.3 Packet Request
Header for definitions of these bits.
This bit has the inverse value of the BCN_FRAME bit contained in the last packet
request header control bytes.
This bit contains the value of the internal USE_R_FLAG flip/flop.
MC68838 USER'S MANUAL
MAC CHIP TYPE (MSB)
MAC REVISION NUMBER