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Hardware Specifications Keyboard with 64 (8x8) Keys 8 Seven-Segment Display Timer Options: hh – mm – ss 8087 Coprocessor Maximum Mode DMA 8237 for Fast Data Transfer UART 8250 for RS232 Port RAM ( FFFF) – EPROM (80000-FFFFF) Clock = *16*4= Hz =7.3728MHz
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A Design Example
A Programmable Calculator
Programmable Calculator
• Working in Exact Mode• Receiving Program from RS232 Port• Saving Programs using RS232 Port• Memory Fill/View/Edit/Search• Switch to floating point calculator• Using DMA for Large Data Transfer
Hardware Specifications
• Keyboard with 64 (8x8) Keys• 8 Seven-Segment Display• Timer Options: hh – mm – ss• 8087 Coprocessor Maximum Mode• DMA 8237 for Fast Data Transfer• UART 8250 for RS232 Port• RAM (00000-7FFFF) – EPROM (80000-FFFFF)• Clock = 115200*16*4=7372800 Hz
=7.3728MHz
CPU Pins in Maximum Mode
GNDAD14AD13AD12AD11AD10AD9AD8AD7AD6AD5AD4AD3AD2AD1AD0NMIINTRCLKGND
VCCAD15A16/S3A17/S4A18/S5A19/S6
RQ/GT0RQ/GT1
QS0
READYRESET
BHE/S7MN/MXRD
LOCKS2S1S0
QS1TEST
1234567891011121314151617181920
3130292827262524232221
4039383736353433328086
Max Mode
GND
S2 S1 S0 Characteristics
0 0 0 Interrupt acknowledge
0 0 1 Read I/O port0 1 0 Write I/O port0 1 1 Halt1 0 0 Code access1 0 1 Read memory1 1 0 Write memory
1 1 1 Passive State
S0, S1 and S2 Signals
8086
CP
U
Clockgenerator
Wait-StateGenerator
CLK
READY
RESET
MN/MX
AD0-AD 15A16-A19 BHE
STBOE
8282Latch
A0 - A19
Address Bus
+5V
RESS0S1S2
CLKS0
S1S2
DATA
8286Transceiver
T
OE
ALE
Gnd
DEN
DT/R
MRDC
MWTC
IORC
IOW C
AIOW C
AMWC
INTA
8288
Bus
Con
trolle
r
8086 System Maximum Mode
8284 Clock Generator for 8086
an 18-pin chip• specially designed to be used with 8088/86 microprocessors,• It provides the clock and synchronization for the microprocessor,• also provides the READY signal for the insertion of wait states into the CPU bus cycle.
7.3728MHz
22.1184MHz
Bank Write and Bank Read Control Logic
Bank Write Control Logic Bank Read Control Logic
A0 A0
2 EPROMs Each 256KB = 256Kx8 = Eight 27512 or 285122 SRAMs Each 256KB = 256Kx8 = Eight 62512 or 61512Total 1M
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOEWE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOEWE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOEWE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOEWE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOEWE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOEWE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOEWE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOEWE
D0 - D7
D8 - D15A1-A16
A1-A16
Y0Y1Y2Y3Y4Y5Y6Y7
A0A1A2
G1 G2
A17A18A19
A0DEN
Y0Y1Y2Y3Y4Y5Y6Y7
A0A1A2
G1 G2
A17A18A19
BHEDEN
RDL RDL
RDU
RDL
RDU
RDU
RDURDU
WRL
WRU
WRL
WRUWRU
WRLWRL
WRU
SRAMs
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOE
A0A1A2A3A4A5A6A7A8A9A10A11A12A13A14A15
D0D1D2D3D4D5D6D7
CSOE
D0 - D7
D8 - D15A1-A16
A1-A16
Y0Y1Y2Y3Y4Y5Y6Y7
A0A1A2
G1 G2
A17A18A19
A0DEN
Y0Y1Y2Y3Y4Y5Y6Y7
A0A1A2
G1 G2
A17A18A19
BHEDEN
RDL RDL
RDU
RDL
RDU
RDL
RDURDU
EPROMs
Peripherals
• 8255 (Keyboard)• 8255 (Display)• Timer 8254• 8259 Interrupt Controller• DMA 8237• Coprocessor 8087• UART 8250
Address Decoding for the Peripherals
8086
8255APPI
A0A1
Latch (‘373)
Display
Y0Y1Y2Y3Y4Y5Y6Y7
X0X1X2
A0A1A2A3A4A5A6A7
CS
8259
A0
CS
AD0-AD7
D0-D7Buffer
ALE Keyboard Address: 000XXPP0Timer Address: 010XXPP0Display Address: 011XXPP0UART Address: 101XPPP08259 Address: 110XXXP0DMA Address: 111PPPP0
IR0IR1
DMA
Keyboard
Timer
UART8259
Address Definition
• Keyboard_BASE EQU 0• Display_BASE EQU 60H• Timer_BASE EQU 40H• UART_BASE EQU 0A0H• DMA_BASE EQU 0E0H• 8259_BASE EQU 0C0H
Connecting 8087 to Processor
8250/16450/16550 UART Connection
A3 A2 A1 (System) A2 A1 A0 (UART)Y5 (Decoder) CS 101XPPP0Line Drivers RS232 io
A0A2A4A6A8AAACADA0A2
Registers
• Transmitter holding register• Receiver buffer register• Interrupt enable register
00001111 A2
Registers
• Interrupt identification register
00000PPP A4
Line Control
00011111 A6 Even Parity, 2 Stop bits, 8 Data bits
Modem Registers
Modem Control Register
Modem Status Register
00000001 A8 DTR Active
status AD
Line Status
Status AA
Divisor Register
Input Clock : 7.3728MHz Required Baud Rate: 9600 bps10000000 A6 DLAB Set0011 0000 A00 A2
Baud Rate Divisor(Decimal) Divisor(hex)
460,800 1 1
115,200 4 4
57,600 8 8
28,800 16 10
38400 12 C
19200 24 18
9600 48 30
Intel Hex Data Format
• : No – Address – Data – Check Sum• :0A 00400 56 78 F6 00 80 80 6C 40 03 02 75
• 56 + 78 + F6 + 80 + 80 + 6C + 40 + 3 + 2 = 375
Commands From RS232
• Upload Data• Download Data• Dump Memory• Fill Memory• Go To Address• Breakpoint• Trace• Register …
Definitions• DISPLAY_SEGMENTS EQU Display_BASE• DISPLAY_GND EQU Display_BASE +2• DISPLAY_CTRL EQU Display_BASE+ 6
• KEYBOARD_ROW EQU Keyboard_BASE• KEYBOARD_COL EQU Keyboard_BASE+2• KEYBOARD_CTRL EQU Keyboard_BASE+6
• TIMER_CH0 EQU Timer_BASE• TIMER_CH1 EQU Timer_BASE+2• TIMER_CH2 EQU Timer_BASE+4• TIMER_CTRL EQU Timer_BASE+6
• IC8259_0 EQU 8259_BASE• IC8259_1 EQU 8259_BASE+2
Main ProgramORG 0FFF0H ;Address FFFF0
• XOR AX,AX ;AX=0• MOV DS,AX ;DS=0• MOV AH,70H ;AX=7000H• MOV SS,AX ;STACK From 7FFFFH• MOV SP,0FFFFH ; SS*10H+SP=7FFFFH• JMP 0F000H:100
Initialize & Main LOOPORG 100H ;Address F0100
• CLI • CALL INIT_KEYBOARD• CALL INIT_DISPLAY• CALL INIT_TIMER• CALL INIT_8259• CALL INIT_DMA• CALL INIT_RS232• STI
• Main_LOOP:• CALL Keyboard_hit• JZ RS232• CALL GETCH ;Scan Code Available in AL• CALL Process_Key• RS232:• CALL RX_AVAILABLE• JZ Main_LOOP• CALL Process_RX• JMP Main_LOOP
INIT_KEYBOARD• INIT_KEYBOARD:• MOV AL,00001011B ;Mode0 output for A &• ;Mode 0 input for B input for C• OUT KEYBOARD_CTRL,AL• MOV AL,0FFH ;OFF All Rows• OUT KEYBOARD_ROW,AL • XOR AL,AL ;Reset FIFO • MOV [Key_head],AL• MOV [Key_tail],AL• RET
INIT_DISPLAY• INIT_DISPLAY:• MOV AL,00001001B ;Mode 0 and out for both A & B. C input• OUT DISPLAY_CTRL,AL• MOV AL,0FFH• OUT DISPLAY_GND,AL ;All 7-Segments off• XOR AX,AX ;Clear ALL Ms of Calc(X,Y,M0-M7)• MOV ES,AX• MOV DI,offset X_SIZE• CLD • MOV CX,10• REP:STOSW ;X_SIZE=Y_SIZE=M_SIZE0-7=0• CALL REFRESH_DISPLAY• RET
REFRESH_DISPLAY• REFRESH_DISPLAY: ; Shows the content of X register• MOV DI,offset DISPLAY_DATA• MOV AX,[X_SIZE]• CMP AX,0• JNE X_NOT_ZERO• XOR AX,AX• MOV WORD PTR [DI],AX• MOV WORD PTR [DI+2],AX• MOV WORD PTR [DI+4],AX• MOV BYTE PTR [DI+6],AL• MOV BYTE PTR [DI+7],10111111B• RET
INIT_TIMER• INIT_TIMER:• MOV AL,00110110B ;Counter 0, 2 Bytes, Mode 3, Binary• OUT TIMER_CTRL,AL• MOV AX,36864 ;7.3728M/36864=200Hz; Refreshing Rate• OUT TIMER_CH0,AL• MOV AL,AH• OUT TIMER_CH0,AL • • MOV AL,01110111B ;Counter 1, 2 Bytes, Mode 3, BCD• OUT TIMER_CTRL,AL• MOV AX,200H ;200Hz/200=1Hz; Time Refresh Rate• OUT TIMER_CH1,AL• MOV AL,AH• OUT TIMER_CH1,AL• RET
INIT_8259
• INIT_8259: • MOV AL,00010011B
;ICW1: Edge - Single - ICW4• OUT IC8259_0,AL• MOV AL,80H ; ICW2=Interupt Type• OUT IC8259_1,AL• MOV AL,00000001B ;ICW4: 8086 Processor• RET
INIT_RS232
• INIT_RS232:
