Machine Characteristics - Timers
Table of Contents

This is one of a number of machine-characteristics.

Timers

The cells in this table each show the values for PC timers 0, 1 and 2 in order. Any unusual settings are marked with a ** symbol.

Machine Timer Read/write modes Counting modes Binary or BCD
Dell Latitude XP 475D laptop. 80486 75MHz. Phoenix BIOS 1.10 0
1
2
11 (both)
01 (msb)
11 (both)
mode 3
mode 2
mode 3
binary
binary
binary
AOpen motherboard. Pentium 3 600MHz. Award BIOS 3.60 0
1
2
11 (both)
01 (msb)
11 (both)
mode 3
mode 2
mode 3
binary
binary
binary
Viglen MPC-L. Geode 399MHz. ION A503 BIOS 0
1
2
11 (both)
01 (msb)
11 (both)
mode 3
mode 3 **
mode 3
binary
binary
binary
Asus EEE 4G netbook. Celeron M ULV 630MHz. AMI ASUS 701 BIOS 0
1
2
11 (both)
01 (msb)
11 (both)
mode 2 **
mode 2
mode 3
binary
binary
binary
Gateway laptop. Dual-core Core 2 T5300 1.7GHz. Phoenix BIOS 0
1
2
11 (both)
01 (msb)
11 (both)
mode 3
mode 2
mode 3
binary
binary
binary
Jetway NC91. Dual-core Atom 1.6GHz. Phoenix-AwardBIOS 0
1
2
11 (both)
01 (msb)
11 (both)
mode 3
mode 2
mode 3
binary
binary
binary

Note that AMI tend to use mode 2 (rate generator) for counter 0 rather than the more-widely used mode 3 (square wave). This doesn't affect the frequency at which interrupts are generated but mode 2 does make it easier to use as a pollable timer.

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