Busy Bit Readable, Command SET xyz | SMC Networks SMC91C95 instruction

I/O SPACE - BANK2
OFFSET	NAME	TYPE	SYMBOL
0	MMU COMMAND REGISTER	WRITE ONLY	MMUCR
		BUSY Bit Readable

This register is used by the CPU to control the memory allocation, de-allocation, TX FIFO and RX FIFO control. The three command bits determine the command issued as described below:

HIGH

BYTE


LOW		COMMAND			0	0	N2	N1	N0/BUS
BYTE					0	0	N2	N1	N0/BUS
BYTE									Y
									Y
	x	y		z

									0

COMMAND SET: xyz

000 0) NOOP - NO OPERATION

0011) ALLOCATE MEMORY FOR TX - N2,N1,N0 defines the amount of memory requested as (value + 1) * 256 bytes. Namely N2,N1,N0 = 1 will request 2 * 256 = 512 bytes. Valid range for N2,N1,N0 is 0 through 5. A shift-based divide by 256 of the packet length yields the appropriate value to be used as N2,N1,N0. Immediately generates a completion code at the ALLOCATION RESULT REGISTER. Can optionally generate an interrupt on successful completion. The allocation time can take worst case (N2,N1,N0 + 2) * 200ns.

0102) RESET MMU TO INITIAL STATE - Frees all memory allocations, clears relevant interrupts, resets packet FIFO pointers.

0113) REMOVE FRAME FROM TOP OF RX FIFO - To be issued after CPU has completed processing of present receive frame. This command removes the receive packet number from the RX FIFO and brings the next receive frame (if any) to the RX area (output of RX FIFO).

1004) REMOVE AND RELEASE TOP OF RX FIFO - Like 3) but also releases all memory used by the packet presently at the RX FIFO output.

1015) RELEASE SPECIFIC PACKET - Frees all pages allocated to the packet specified in the PACKET NUMBER REGISTER. Should not be used for frames pending transmission. Typically used to remove transmitted frames, after reading their completion status. Can be used following 3) to release receive packet memory in a more flexible way than 4).

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SMC Networks SMC91C95 manual Busy Bit Readable, High Byte LOW Command N0/BUS, Command SET xyz, 000 0 Noop no Operation

Contents

Features Bus Interface Table of Contents Software Drivers PIN ConfigurationNetwork Interface General Description OverviewPage Pcmcia Uses non-volatile jumperless setup via serial EepromISA Function ISA Pcmcia Number Pins PIN Requirements Crystal OSC XTAL1 XTAL2 Power VDD Avdd Ground GND Total PinsRecp Coln PIN no Name Symbol Type Description Description of PIN Functions ISA Byte High Enable input. Asserted low Pcmcia Card Enable 2 input. Used toEnable Select card on odd byte accesses Ready Reset Application of the VCC or Reset which ever ISA Output. Active high interrupt signal.Value of INT SEL1-0 bits in the Configuration Register. This interrupt is tri-stated when not Whenever the SMC91C95 is in 16 bit mode Enable Function bit in the EcorIs with Input. Active low read strobe used to access Interrupt pin if enabled Pin is active high when either the Pwrdwn Output B Powerdown mode Pwrdwn bit is zeroValue of the Mringin input. When entering Pin when enabled by the Audio bit Modem Eeprom Eesk Eeprom EecsEeprom Eedo Sdout Eeprom Rxclk TXDRegister AUI Txclk Tperxn TPE TpetxpTPE Tpetxdp Endec VSSAvss Buffer Types SMC91C95 SMC91C95 SMC91C95 Internal Block Diagram Functional Description Bus Transactions in ISA Mode NSBHE D0-D7 D8-D15BIT Mode Bus Transactions in Pcmcia Mode NCE1 NCE2 D0-D7 D8-D15 Even byte IOis8=1 + nEN16=1.16BIT=0No Cycle Even byte ROM Signals ISA Pcmci ON-CHIP Depth Width UsedSMC91C95 Address Spaces Buffer Memory Mapping and Paging VS. Receive and TX Area Fifo CPU Side TX FifoTX Completion Receive Queue and Mapping Block Diagram SMC91C95Internal With Packet Format in Buffer Memory Transmit Packet Receive Packet Byte before the Control Byte should be ignored ODD CRCODD Receive Frame Status Word Address Hash Value Multicast Table BIT Function Pcmcia Mode ISA Mode Interrupt Output NIREQ when either function isInterrupt Structure SMC91C95 Interrupt Merging Reset Logic Reset FunctionsEcor Mcor Powerdown Logic Powerdown FunctionsPowerdown Powers Does not Entered Exited Power Down Pwrdwn Pcmcia Configuration Registers Address 8000-803Eh Pcmcia Attribute Memory Address 0- 7FFEh Attribute Memory Address Using Serial Eeprom 7FFEh 8000h 803Eh ISA and Pcmcia Mode TypesymbolSpace Offsetname Internal I/O Space Mapping BANK0 BANK1 BANK2 BANK3 BANK4 BANK5 Bank Select Register Offset Name Type Symbol READ/WRITE BSR High Byte LOW BS2BS0 BS2 BS1 BS0 BANK# High Fdse EPH STP Fdupl MON Nocrc Byte Loop Sqet LOW Pade Forco Loop Txena Byte Transmits AUI Fdse Fduplx Ephloop Loop Loops AT Network High Link CTR EXC Lost Latcol Wakeu Byte OvrnCarr LOW LTX Sqet LTX MULPage High Soft Strip Rxen Byte RST CARLOW Almul Prms Byte Abort Rxabort RxovrnintPage Memory Size Actual Memory Register FFH Space BANK0 Offset Name Type Symbol Memory Configuration MCRRegister READ/WRITE Device High Full SET AUI Byte Wait Step SelecDIS INT Byte INT SEL1 INT SEL0 Interrupt PIN Used A15 A14 A13 Byte LOW ROM SizeRA17 RA15 RA14 High Address Byte LOW High Byte LOW Byte High Data Byte LOW Data Byte Wakeu Auto Byte BAD Release LOW Eeprom Reload Store Byte EnableHigh RCV Pcmcia Eeprom to Sram Memory Map 3FA 3FC3FD 3FF High Byte LOW Command N0/BUS Command SET xyzBusy Bit Readable 000 0 Noop no Operation Command Sequencing This register is updated upon an Allocate Memory MMU command Failed Allocated Packet NumberPage Page Data Register READ/WRITE Data High Data LOW Space BANK2 Offset Name Type SymbolThrough Ah Ercv EPH INT Rxovr Alloc TX INT RCV INT Empty Ercv INT Rxovr Empty TX INTPage INT LOW Multicast Table Byte High NXNDE IOS2 IOS1 IOS0 Byte LOW Mdoe Mclk MDI MDOMDOE=0 MDOE=1 Bit MDO High Byte LOW Byte Chip REV Chip ID Value Device High Byte LOW RCV Byte Discr Full Duplex Ethernet Support Theory of OperationMemory Architecture Behavior in Fdse Mode Main 802.3 section affected by Fdse is Typical Flow of Events for Transmit Driver CSMA/CD Side Typical Flow of Events for Receive Driver CSMA/CD Side Ethernet Interrupt Service Routine CSMA/CD MMU RAM RX Intr TX Intr Assumes Auto Release Option Selected Txempty Intr Driver Send and Allocate Routines Memory Partitioning Interrupt Generation Internal VS. External Attribute Memory MAP Attribute Memory Decodes Using Serial Eprom Pcmcia Configuration Registers Description SresetWrattri Ireq 8002h Ethernet Configuration and Status Register Ecsr IOIs8Page LevIREQ Enable Pcmcia functionality, this bit must be set IOIs8 Reserved Audio 8024h Pin Replacement Register PRR Current Value Value Written NEW Value Ringevent Ringenable 8028h Extended Status RegisterESR 802Ah Modem I/O Base Register 802Ch Modem I/O Base Register A15 A14 A13 A12 A11 A10 8032h Modem I/O Size Register Arbiter Functional Description of the BlocksMemory Management Unit BUS Interface Wait State Policy DMA Block Packet Number Fifos DMA MMU Packet Number Flow and Relevant Registers Csma Block Network Interface 10BASE-TAUI Physical Interface Transmit Functions Receive Functions Page Board Setup Information ISA Mode Ethernet Individual Address I/O Base AddressEeprom Word Register Address Diagnostic LEDs Arbitration ConsiderationsPage 64 X 16 Serial Eeprom MAP for ISA Mode 103 Parameter Symbo MIN TYP MAX Units Comments Maximum Guaranteed RatingsOperational Description Input Leakage IP Type BuffersID Type Buffers Type Buffer OD16 Type Buffer OD162 Type BufferOD24 Type Buffer Limits Parameter Symbo MIN TYP MAX Unit Test Condition INTRO-INTR3 Parameter MIN TYP MAX UnitsCapacitive Load on Outputs Timing Diagrams A50, nREG NCE1 NOE D150 30 max Max MinData Valid 108 109 Address/nREG Setup Time to NWE LowNWE High NCE1 Low to nWE High Setup O Read Timing Table on the following 110 Parameter Min Typ Max Units O Write Timing Table on the following 112 100 Card Configuration Registers READ/WRITE Pcmcia Mode A15=1 114 NINPAC 115 Consecutive Pcmcia Write Cycles 116 Pcmcia Attribute Memory READ/WRITE A15=0 117 Mringoutb 118 ISA Consecutive Read Cycles 119 ISA Consecutive Write Cycles 120 ISA Consecutive Read and Write Cycles 121 Data Register Special Read Access 122 Data Register Special Write Access 123 BIT Mode Register Cycles 124 ISA Register Access When Using Bale 125 External ROM Read Access Using Bale 126 Eeprom Read 127 Eeprom Write 128 Memory Read Timing 129 External Endec Interface Start of Transmit 130 Differential Output Signal Timing 10BASE-T and AUI 131 Recp Recn Tperxpn Tperxp Tperxn Recp Recn Transmit Timing END of Frame AUI and 10BASE-T 134 Collision Timing AUI 135 Vtqfp Package Outline 136Page Kennedy Drive Hauppauge, NY 516 435-6000 FAX 516