8088 5mhz memory speed ns3/17/2023 Low / Even Bank High / Odd Bank 8086 8088 Bank – select signalsĢ9 Byte / Word Transfer 8088 8088 byte transfer 8088 word transferģ0 Question A memory cycle for an 8088 running at 5Mhz has no wait / idle state.The 8088 was designed at Intel's laboratory in Haifa, Israel, as were a large number of Intel's processors. Wait State – Triggered by events external to MPU – Buffer full will trigger a wait state – Triggered by READY pin – Inserted between T3 and T4Ģ5 What is the duration of the bus cycle in the 8088 based microcomputer if the clock is 8MHz and two wait states are inserted The duration of the bus cycle is in an 8MHz system is given in general by Tcyc = 500 ns + N x 125ns Tcyc = 500 ns +2 x 125ns = 750 nsĢ6 What is the duration of the bus cycle in the 8086 based microcomputer if the clock is 5MHzĪ)No wait state ? b)with three wait states are inserted.Ģ7 8.8 HARDWARE ORGANIZATION OF THE MEMORY ADDRESS SPACEĢ8 Hardware Organization of the memory Address Space.– Each is 1 clock period long – Occurs when instruction queue is full or the MPU does not need to read/write to memory T-State: One clock period is referred to as a T-State T-State An operation takes an integer number of T-States CPU Bus Cycle: A bus cycle consists of 4 or more T-States T1 T2 T3 T4 For the write cycle, the trailing edge of the WR signal transfers data to the memory or I/O, which activates and write when WR returns to logic 1 level. The 8088 also finishes sampling the data (in a read cycle) in this period. T4 - all bus signals are deactivated in preparation for the next clock cycle. If the bus cycle is a read cycle, the data bus is sampled at the end of T3. T3 - this clock period is provided to allow memory to access the data. The READY input to the CPU is sampled at the end of T2 and if READY is low, a wait state TW (one or more) is inserted before T3 begins. The DEN turns on the data bus buffers to connect the CPU to the external data bus. T2 - the RD or WR control signals are issued, DEN is asserted and in the case of a write, data is put onto the data bus. Actions include setting control signals to give the required values for ALE, DTR, IO/M putting a valid address onto the address bus. T2 – Change direction of Data bus for READ instructions.T1 – Address placed on bus – ALE active.Bus cycle will complete when READY = 1Ģ0 – Change direction of Data bus for READ instructions These 4 clock states gives a bus cycle duration of ( 125 ns * 4 ) = 500 ns in a 8-Mhz 8088 Idle State: no bus activity one clock period Wait state : controlled by READY signal inserted between T3 and T4 when READY = 0. These clock period are also called T-state. Each bus cycle consists of at least four clock periods, T1, T2, T3 and T4. During these operations, a series of control signal are also produced by the MPU to control the direction and timing of the bus. A bus cycle corresponds to a sequence of events that starts with an address being output on the system bus followed by a read or write data transfer. Examples of bus cycle are memory read, memory write, input/output read and input/output write. ( FCF) 33% duty cycle the FCF is divided by 3 internally by 8244 to provide the necessary CLK output pin pclk provide 50% of duty cycle to drive periperal devicesĪ bus cycle defines the basic operation that a microprocessor performs to communicate with external devices. READY used to slow down the 8088 Dfrom IO circuit thru RD1 and RD2 A crystal oscillator is connected between X1 and X2 which provides a FUNDAMENTAL CRYSTAL FREQUENCY. The RESET signal does resets the This line can also be used by other peripherals on the computer so that they reset when the 8088 resets. INTA TEST NMI RESET HOLD HLDA Address / data bus AD0-AD15, A16/S3-A19/S6 ALE _ BHE/S7 M/IO’ DT/R’ _ RD WR DEN READY Interrupt interface 8086 MPU Memory/IO controls DMA interface Mode Select MN/MX’ CLKġ0 SYSTEM CLOCK Clock (CLK) : input signal which synchronize the internal and external operations of the microprocessor.ġ1 CLOCK GENERATOR IC The clock source is generated by 8284 ( clock generator and Driver IC ) CLK ( 8) of 8284 is connected to pin /8086 8284 also supplies it with 2 of it's control lines – RESET and READY. Athaur Rahman Bin Najeeb Room 2.105 Website: Consultation : Tuesday am ( appointment)Ħ 8086 Minimum-Mode Signals 8086 MPU Power supply Vcc GND INTR _ 1 ECE Microprocessor and Interfacing Chapter /8086 Microprocessors and their memory and I/O interfaces Br.
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