ISR
Save Bank Select & Address
Ptr Registers
Mask SMC91C100 Interrupts
Read Interrupt Register
No
Yes
RX INTR?
Yes
TX INTR?
Call TX INTR or TXEMPTY
INTR
No
Call RXINTR
Get Next TX
ALLOC INTR?
Packet
No
Yes
Available for
Transmission?
Write Allocated Pkt # into
Packet Number Reg.
Yes
No
Call ALLOCATE
Write Ad Ptr Reg. & Copy Data
& Source Address
Enqueue Packet
EPH INTR?
Yes
No
Set "Ready for Packet" Flag
Return Buffers to Upper Layer
Restore Address Pointer &
Bank Select Registers
Call EPH INTR
Unmask SMC91C100
Interrupts
Disable Allocation Interrupt
Mask
Exit ISR
55
SMSC [ SMSC CORPORATION ]
