PIC1          equ 0x20      ; IO base for master PIC
PIC2          equ 0xA0      ; IO base for slave PIC

PIC1_COMMAND  equ PIC1      ; Port for Command for master PIC
PIC1_DATA     equ (PIC1+1)  ; Port for Data    for master PIC
PIC2_COMMAND  equ PIC2      ; Port for Command for slave PIC
PIC2_DATA     equ (PIC2+1)  ; Port for Data    for slave PIC

PIC_CMD_EOI   equ 0x20  ; End-Of-Interrupt command


ICW1_ICW4        equ 0x01  ; ICW4 (not) needed
ICW1_SINGLE      equ 0x02  ; Single (cascade) mode
ICW1_INTERVAL4   equ 0x04  ; Call address interval 4 (8)
ICW1_LEVEL       equ 0x08  ; Level triggered (edge) mode
ICW1_INIT        equ 0x10  ; Initialization - required!
 
ICW4_8086        equ 0x01  ; 8086/88 (MCS-80/85) mode
ICW4_AUTO        equ 0x02  ; Auto (normal) EOI
ICW4_BUF_SLAVE   equ 0x08  ; Buffered mode/slave
ICW4_BUF_MASTER  equ 0x0C  ; Buffered mode/master
ICW4_SFNM        equ 0x10  ; Special fully nested (not)