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ja_rd |
0001 0000 ;*******************************************************************************
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0002 0000 ; tb1.asm -- light8080 core basic demo: 'Hello World!"
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0003 0000 ;*******************************************************************************
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0004 0000 ; Should be used with SoC vhdl\soc\l80soc.vhdl
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0005 0000 ; Assembler format compatible with TASM for DOS and Linux.
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0006 0000 ;*******************************************************************************
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77 |
ja_rd |
0007 0000 ; This program will print a Hello message to a 9600/8/N/1 serial port, then
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74 |
ja_rd |
0008 0000 ; will loop forever copying the input port P1 to the output port P2.
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0009 0000 ; This demo is meant to be used as a starting point for those wanting to play
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0010 0000 ; with the l80soc core -- which in turn is little more than an usage example
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0011 0000 ; for the light8080 cpu core.
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0012 0000 ; See the readme file for instructions for setting up a project with this
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0013 0000 ; program on Digilentic's DE-1 development board.
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0014 0000 ;*******************************************************************************
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0015 0000
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0016 0000 ; DS pseudo-directive; reserve space in bytes, without initializing it
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0017 0000 #define ds(n) \.org $+n
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0018 0000
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0019 0000 MASK_RX_IRQ: .equ 20h
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0020 0000 MASK_TX_IRQ: .equ 10h
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0021 0000 MASK_RX_RDY: .equ 02h
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0022 0000 MASK_TX_RDY: .equ 01h
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0023 0000
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0024 0000 UART_DATA: .equ 80h
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0025 0000 UART_STATUS: .equ 81h
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0026 0000 UART_BAUDL: .equ 82h
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0027 0000 UART_BAUDH: .equ 83h
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0028 0000 IRQ_ENABLE: .equ 88h
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0029 0000
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0030 0000 P1IN: .equ 84h
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0031 0000 P2OUT: .equ 86h
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0032 0000
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0033 0000
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0034 0000 ;*******************************************************************************
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0035 0000
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0036 0000 .org 0H ; Reset entry point
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0037 0000 C3 60 00 jmp start ; Skip the rst address area
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0038 0003
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0039 0003 ;***** Interrupt vectors in area 0008h-0038h *****************
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0040 0003
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0041 0008 .org 0h+(1*8) ; interrupt vector 1
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0042 0008 C9 ret
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0043 0010 .org 0h+(2*8) ; interrupt vector 2
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0044 0010 C9 ret
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0045 0018 .org 0h+(3*8) ; interrupt vector 3
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0046 0018 C9 ret
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0047 0020 .org 0h+(4*8) ; interrupt vector 4
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0048 0020 C9 ret
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0049 0028 .org 0h+(5*8) ; interrupt vector 5
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0050 0028 C9 ret
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0051 0030 .org 0h+(6*8) ; interrupt vector 6
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0052 0030 C9 ret
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0053 0031
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0054 0038 .org 0h+(7*8) ; interrupt vector 7
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0055 0038 C3 A7 00 int38h: jmp irq_uart ; UART interrupt
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0056 003B
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0057 003B ;***** program entry point *******************************************
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0058 003B
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0059 0060 start: .org 60H
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0060 0060 31 50 01 lxi sp,stack
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0061 0063
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0062 0063 ; Initialize UART RX and TX buffers
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0063 0063 21 EB 00 lxi h,void_buffer
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0064 0066 22 EC 00 shld ptr_tx
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0065 0069 21 F0 00 lxi h,rx_buffer
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0066 006C 22 EE 00 shld ptr_rx
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0067 006F ; Set up UART baud rate to 9600 bauds @ 50MHz:
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ja_rd |
0068 006F ; (50E6 / 9600) = 5208d = 1458h
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0069 006F 3E 14 mvi a,14h
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ja_rd |
0070 0071 D3 83 out UART_BAUDH
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0071 0073 3E 58 mvi a,58h
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0072 0075 D3 82 out UART_BAUDL
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0073 0077
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0074 0077 ; Clear P2 port
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0075 0077 3E 00 mvi a,00h
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0076 0079 D3 86 out P2OUT
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0077 007B
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0078 007B ; Set up interrupts
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0079 007B 3E 08 mvi a,08h ; Enable UART irq...
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0080 007D D3 88 out IRQ_ENABLE
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0081 007F FB ei ; ...and enable interrupts in the CPU
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0082 0080
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0083 0080 ; print hello message to console
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0084 0080 21 96 00 lxi h,msg_hello
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0085 0083 CD DE 00 call print_string
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0086 0086
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0087 0086 forever:
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0088 0086 DB 84 in P1IN
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0089 0088 4F mov c,a
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0090 0089 07 rlc
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0091 008A 07 rlc
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0092 008B 81 add c
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0093 008C D3 86 out P2OUT
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0094 008E C3 86 00 jmp forever
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0095 0091
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0096 0091 F3 di
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0097 0092 76 hlt
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0098 0093 C3 93 00 done: jmp done
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0099 0096
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0100 0096 0A 0D 0A 48 msg_hello: .text "\n\r\nHello World!$\000"
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0100 009A 65 6C 6C 6F
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0100 009E 20 57 6F 72
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0100 00A2 6C 64 21 24
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0100 00A6 00
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0101 00A7
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0102 00A7 ;irq_uart: UART interrupt processing
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0103 00A7 irq_uart:
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0104 00A7 E5 push h
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0105 00A8 F5 push psw
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0106 00A9
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0107 00A9 ; Deal with RX interrupt (if any) first and then the TX interrupt.
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0108 00A9 DB 81 in UART_STATUS ; Is there new data in the RX register?
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0109 00AB E6 20 ani MASK_RX_IRQ
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0110 00AD CA C0 00 jz irq_uart_rx_done ; If there isn't, process TX interrupt.
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0111 00B0
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0112 00B0 ; Process UART RX interrupt
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0113 00B0 irq_uart_rx:
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0114 00B0 3E 20 mvi a,MASK_RX_IRQ ; Clear IRQ flag.
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0115 00B2 D3 81 out UART_STATUS
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0116 00B4 DB 80 in UART_DATA ; Get RX byte...
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0117 00B6 D3 86 out P2OUT ; ...display it in the output port...
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0118 00B8 2A EE 00 lhld ptr_rx ; ...and store it in the rx buffer.
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0119 00BB 77 mov m,a
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0120 00BC 23 inx h
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0121 00BD 22 EE 00 shld ptr_rx ; Update the rx buffer pointer.
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0122 00C0 ; Note there's no check for RX buffer overrun!
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0123 00C0
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0124 00C0 irq_uart_rx_done:
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0125 00C0 ; Ok, RX is done. Now deal with TX irq, if any
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0126 00C0 DB 81 in UART_STATUS ; Is the TX buffer re new data in the RX register?
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0127 00C2 E6 10 ani MASK_TX_IRQ
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0128 00C4 CA DA 00 jz irq_uart_end ; If there isn't, we're done.
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0129 00C7
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0130 00C7 ; process UART TX interrupt
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0131 00C7 irq_uart_tx:
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0132 00C7 3E 10 mvi a,MASK_TX_IRQ ; Clear IRQ flag.
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0133 00C9 D3 81 out UART_STATUS
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0134 00CB 2A EC 00 lhld ptr_tx ; Get next byte from the TX buffer
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0135 00CE 7E mov a,m
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0136 00CF FE 24 cpi '$' ; Did we reach the end of the buffer?
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0137 00D1 CA DA 00 jz irq_uart_tx_done ; If we did, we're done here...
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0138 00D4 23 inx h ; ...otherwise increment the TX pointer...
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0139 00D5 22 EC 00 shld ptr_tx
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0140 00D8 D3 80 out UART_DATA ; ...and transmit the data byte.
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0141 00DA
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0142 00DA irq_uart_tx_done:
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0143 00DA
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0144 00DA irq_uart_end:
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0145 00DA F1 pop psw ; Done, quit.
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0146 00DB E1 pop h
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0147 00DC FB ei
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0148 00DD C9 ret
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0149 00DE ; Note there's no check for RX buffer overrun! we shouldn't need it
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0150 00DE ; in this program, anyway.
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0151 00DE
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0152 00DE
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0153 00DE ;print_string: print $-terminated string at HL
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0154 00DE ; Returns as soon as the transmission has started; transmission proceeds in
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0155 00DE ; 'background' through the UART interrupt service routine.
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0156 00DE print_string:
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0157 00DE ; We don't check if there's a transmission going on, we just start
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0158 00DE ; transmitting. Not suitable for real use!
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0159 00DE 7E mov a,m ; Get first character from string...
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0160 00DF 23 inx h ; ...and move updated string pointer to TX
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0161 00E0 22 EC 00 shld ptr_tx ; buffer pointer.
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0162 00E3 FE 24 cpi '$' ; Kickstart transmission by sending 1st byte...
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0163 00E5 CA EA 00 jz print_string_end; ...unless its the end of string marker.
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0164 00E8 D3 80 out UART_DATA ;
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0165 00EA print_string_end:
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0166 00EA C9 ret
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0167 00EB
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0168 00EB
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0169 00EB ; data space, placed immediately after object code in memory
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0170 00EB 24 void_buffer: .text "$"
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0171 00EC ptr_tx: ds(2)
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0171 00EE
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0172 00EE ptr_rx: ds(2)
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0172 00F0
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0173 00F0 rx_buffer: ds(32)
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0173 0110
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0174 0110 ds(64)
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0174 0150
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0175 0150 stack: ds(2)
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0175 0152
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0176 0152 .end
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0177 0152 tasm: Number of errors = 0
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