Intel® 845G/845GL/845GV GMCH Chipset System Clock and AGP Characteristics

Intel® 845G/845GL/845GV GMCH Chipset System Clock and AGP Characteristics - The figure shows a block diagram of an 845G chipset-based system (enlarged

Intel® 845G/845GL/845GV GMCH Chipset System Clock and AGP Characteristics - The figure shows a block diagram of an 845G chipset-based system (enlarged click).

The type of this series which is known as Intel 82845G GMCH has the following clocks. There are:

• 100/133 MHz, Spread spectrum, Low voltage (0.7 V) Differential HCLKP/HCLKN for PSB

• 66.667 MHz, Spread spectrum, 3.3 V GCLKIN for hub interface and AGP

• 48 MHz, Non-Spread spectrum, 3.3 V DREFCLK for the Display frequency syntheses

• Up to 85 MHz, 1.5 V DVOBC_CLKINT for TV-Out mode

The AGP Electrical characteristics shows that the 4X data transfers use 1.5 V signaling levels. Also, The GMCH supports 1X/2X/PCI data transfers using 1.5 V signaling levels.

The table below shows the data rates and signaling levels supported by the GMCH:

Data Rate	Signaling Level
	1.5 V	3.3 V
PCI-66	Yes	No
1X AGP	Yes	No
2X AGP	Yes	No
4X	Yes	No

The low voltage pins receive a host clock from the external clock synthesizer. The graphics engine uses this clock and so do the host interface and system memory logic.

You can follow on complete Intel® 845G/845GL/845GV GMCH Chipset with System Clock and AGP Characteristics within in its Datasheet, just jump at page 137-138. (source: intel.com)

Tags: clock synthesizer, AGP Characteristics, Chipset Datasheet, Intel System Clock, hub interface,