The document provides information about the 8085 microprocessor. It describes the 8085 as an 8-bit processor with 40 pins that can access 64KB of memory and 256 I/O ports. It has 5 hardware interrupts, 8 general purpose registers including the program counter and stack pointer, and provides 74 instructions across 5 addressing modes.

3. 8085 PIN DIAGRAM

7. 8085 ARCHITECTURE

14. INSTRUCTIONS SET OF 8085 DATA TRANSFER GROUP MOV Rd, Rs .(Move data from Rs to Rd). Example: MOV C,B. Move the content of register B to C. Initially After execution B=10H. B=10H. C=20H. C=10H. Flags Affected :No flags affected. Addressing mode: Register.

80. 8255 PIN DIAGRAM PA0-PA7 I/O Port A Pins PB0-PB7 I/O Port B Pins PC0-PC7 I/O Port C Pins D0-D7 I/O Data Pins RESET I Reset pin RD ¯ I Read input WR ¯ I Write input A0-A1 I Address pins CS ¯ I Chip select Vcc , Gnd I +5volt supply

81. 8255 BLOCK DIAGRAM

83. 8255 BLOCK DIAGRAM A 0 ,A 1 decide the port to be used in 8255. A 1 A 0 Selected port 0 0 Port A 0 1 Port B 1 0 Port C 1 1 Control Register

89. INTERFACING 8085 & 8255 8255 8085 3:8 decoder 74373 (AD0-AD7) D7-D0 A0-A7 /CS A0 A1 O0 O1 O7 A13 A12 A11 ALE RD ¯ WR ¯ RD¯ WR¯ G2A G2B G1 A15 A14 IO/M A B C PA PB PC

91. INTERFACING STEPPER MOTOR with 8255

100. INTERRUPT PRIORITY Interrupt name Mask-able Vectored TRAP No Yes RST 7.5 Yes Yes RST 6.5 Yes Yes RST 5.5 Yes Yes INTR YES NO

104. 8253 PIT

106. CONTROL WORD D0 D7 SC1 SC0 Select counter RL1 RL0 Read/Load SC1 SC0 RL1 RL0 M2 M1 M0 BCD 0 0 Counter0 0 1 Counter1 1 0 Counter2 1 1 ILLEGAL 0 0 Counter latching 0 1 Read/load LSB 1 0 Read/load MSB 1 1 R/L MSB 1 st then LSB.

107. CONTROL WORD M2 M1 M0 BCD =0 Binary counter BCD =1 BCD counter 0 0 0 Mode 0 0 0 1 Mode 1 X 1 0 Mode 2 X 1 1 Mode 3 1 0 0 Mode 4 1 0 1 Mode 5

110. DMA