133 lines
3.0 KiB
NASM
133 lines
3.0 KiB
NASM
jp Sysinit ; Startup vector: DO NOT MOVE! Must be the first instruction
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; Pat80 BIOS v0.01
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; @author: Daniele Verducci
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;
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; MEMORY MAP
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; ROM is at 0x0000
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; RAM is at 0x8000
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; SYSTEM VAR SPACE: 0x8000 - 0x8FFF (4kb)
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; DRIVERS VAR SPACE: 0x9000 - 0x9FFF (4kb)
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; APPLICATION VAR SPACE: 0xA000 - 0xFFFF (24kb)
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; I/O MAP
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; I/O 0 (0x00 - 0x1F) Parallel terminal (uses addr 0x00 and 0x01)
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; I/O 1 (0x20 - 0x3F) Sound card (uses addr 0x20 only)
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; I/O 2 (0x40 - 0x5F) PS2 Keyboard (uses 0x40 and 0x41)
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; I/O 3 (0x60 - 0x7F)
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; I/O 4 (0x80 - 0x9F)
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; I/O 5 (0xA0 - 0xBF)
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; I/O 6 (0xC0 - 0xDF)
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; I/O 7 (0xE0 - 0xFF)
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; **** RESET/INTERRUPT VECTOR ****
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; Maskable interrupt mode 1: when the BREAK key is pressed,
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; a maskable interrupt is generated and the CPU jumps to this address.
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; In this way, BREAK key brings up memory monitor at any time.
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ds 0x38
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di ; Disable maskable interrupts.
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exx ; exchange registers
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ex af, af'
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jp Monitor_main
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; **** SYSTEM CALLS ****
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; System calls provide access to low level functions (input from keyboard, output to screen etc).
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; The name starts always with Sys_
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ds 0x40 ; Place system calls after Z80 reset/interrupt subroutines space
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; Returns ABI version.
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; (ABI -> https://en.wikipedia.org/wiki/Application_binary_interface)
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; Any Pat80 application should check the ABI version on startup, and refuse to run if not compatible.
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; @return bc the ABI version
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Sys_ABI:
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ld bc, 0
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ret
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; Prints string
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; @param BC Pointer to a null-terminated string first character
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Sys_Print:
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jp Term_print
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; Writes a single character
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; @param A Value of character to print
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Sys_Printc:
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jp Term_printc
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; Reads a single character
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; @return A The read character
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Sys_Readc:
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;jp Term_readc
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jp PS2Keyb_readc
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; Reads a line
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; @return BC The pointer to a null-terminated read string
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Sys_Readline:
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jp Term_readline
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; Emits system beep
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Sys_Beep:
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jp Snd_beep
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; MEMORY CONFIGURATION
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SYS_VAR_SPACE: EQU 0x8000
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DRV_VAR_SPACE: EQU 0x9000
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APP_SPACE: EQU 0xA000
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; SYSTEM CONFIGURATION
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IO_0: EQU 0x00
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IO_1: EQU 0x20
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IO_2: EQU 0x40
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IO_3: EQU 0x60
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IO_4: EQU 0x80
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IO_5: EQU 0xA0
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IO_6: EQU 0xC0
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IO_7: EQU 0xE0
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;include 'drivers/hd44780.asm'
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;include 'drivers/keyboard.asm'
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include 'drivers/ps2_keyboard.asm'
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include 'drivers/arduino_terminal.asm'
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include 'drivers/sn76489.asm'
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include 'monitor.asm'
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include 'libs/time.asm'
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;include 'tests/sndtest.asm'
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; **** SYSTEM INITIALIZATION ****
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Sysinit:
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; Init snd driver
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call Snd_init
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; Init video
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; TODO
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; Wait for audio amp to unmute
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ld bc, TIME_DUR_SECOND
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call Time_delay55
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; Play startup sound
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call Sys_Beep
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; Run memory monitor
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ei ; enable maskabpe interrupts
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im 1 ; set interrupt mode 1 (on interrupt jumps to 0x38)
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rst 0x38 ; throw fake interrupt: jump to interrupt routine to start monitor
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; User exited from memory monitor without loading a program. Do nothing.
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mloop:
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; Main loop: do nothing.
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jp mloop
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; DEBUG: Echo chars
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; loop:
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; call Term_readc
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; call Term_printc
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; jp loop
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