Différences

Ci-dessous, les différences entre deux révisions de la page.

--- back2root:ibm-pc-ms-dos:hardware:8259 [2022/12/29 02:57] – [8259 Programmable Interrupt Controller Notes] frater
+++ back2root:ibm-pc-ms-dos:hardware:8259 [2022/12/29 13:03] – [Initialization Command Word 1 at Port 20h and A0h] frater
@@ Ligne 1: / Ligne 1: @@
+~~TOC 1-4 ~~
 ====== 8259 - Programmable Interrupt Controller (PIC) ======
 ==== Initialization Command Word 1 at Port 20h and A0h ====
-<code>
+^  Bit  ^ Initiali                                           ^
-|7|6|5|4|3|2|1|0|  ICW1
+|  0    | 0=no ICW4 needed\\ 1=ICW4 is needed                |
- | | | | | | | `---- 1=ICW4 is needed, 0=no ICW4 needed
+|  1    | 0=cascading 8259's\\ 1=single 8259                 |
- | | | | | | `----- 1=single 8259, 0=cascading 8259's
+|  2    | 0=8 byte int vectors\\ 1=4 byte interrupt vectors  |
- | | | | | `------ 1=4 byte interrupt vectors, 0=8 byte int vectors
+|  3    | 0=edge triggered mode\\ 1=level triggered mode     |
- | | | | `------- 1=level triggered mode, 0=edge triggered mode
+|  4    | must be 1 for ICW1 (port must also be 20h or A0h)  |
- | | | `-------- must be 1 for ICW1 (port must also be 20h or A0h)
+|  5-7  | must be zero for PC systems                        |
- `------------- must be zero for PC systems
-</code>
 ==== Initialization Command Word 2 at Port 21h and A1h ====
@@ Ligne 46: / Ligne 45: @@
  `-------------- unused (set to zero)
 </code>
 ^  Bits       |^ Buffering Mode                  ^
@@ Ligne 103: / Ligne 104: @@
   * ISR - In Service Register, tracks IRQ line currently being serviced. \\ Updated by EOI command.
-===== Hardware Interrupt Sequence of Events: ======
+====== Hardware Interrupt Sequence of Events: ======
   - 8259 <A HREF="int_table.html">IRQ</A> signal is raised high by hardware setting the corresponding IRR bits true.