24888 Rev 3.03 - July 12, 2004

AMD-8151TMAGP Tunnel Data Sheet

 

 

15:14

PCTL: AGP PHY P (rising edge) compensation control. Read-write. These two bits combine to

 

specify the PHY rising edge compensation value that is applied to AGP signals as follows:

 

PCTL

Description

 

 

00b

Apply PCOMP directly as the compensation value.

 

01b

Apply PDATA directly as the compensation value.

 

10b

Apply the sum of PCOMP and PDATA as the compensation value. If the sum exceeds

 

 

1Fh, then 1Fh is applied.

 

 

11b

Apply the difference of PCOMP minus PDATA as the compensation value. If the dif-

 

 

ference is less than 00h, then 00h is applied.

 

 

 

 

 

13:12

Reserved.

 

 

 

 

 

11

RW: read-write bit. Read-write. This controls no logic.

 

 

 

10:6

PDATA: AGP rising edge drive strength control. Read-write. This value is applied to the rising-

 

edge (P transistor) PHY compensation as described in PCTL.

 

 

 

 

 

5

Reserved.

 

 

 

 

4:0

PCOMP: AGP rising edge drive strength. Read only. This provides the calculated value of the ris-

 

ing-edge (P transistor) drive strength of the AGP signals. The default for this field varies. This field is

 

updated by the hardware approximately every 8 microseconds.

 

 

 

 

AGP PHY Skew Control Register

DevA:0x58

 

 

 

 

DSKEW and SSKEW are designed such that when they are both programmed to the same value, the AGP out- put strobes transition near the center of the data eye. To move the strobe to a later point in the data eye, the value of SSKEW is increased. To move the strobe to an earlier point in the data eye, DSKEW is increased. These values translate into skew approximately as follows:

For values 0h to 8h, the skew is about: [D, S]SKEW x 80 picoseconds.

For values 9h to Fh, the skew is about: 800 + ([D, S]SKEW - 8) x 400 picoseconds.

However, these values vary with process, temperature, and voltage. Note that the lower values provide fine res- olution and the upper values provide coarse resolution.

Default: 0000 0000h.

Attribute: Read-write.

Bits

Description

 

 

 

 

31:8

Reserved.

 

 

 

7:4

DSKEW: AGP data skew. Read-write. This specifies the alignment of the AGP data signal outputs,

 

A_AD[31:0], A_CBE_L[3:0], and A_DBI[H, L], relative internal clocks. 0h=The strobe transitions

 

earliest. Fh=The strobe transitions latest.

 

 

 

3:0

SSKEW: AGP strobe skew. Read-write. This specifies the alignment of the AGP strobe signal out-

 

puts, A_ADSTB[1:0], relative internal clocks. 0h=The strobe transitions earliest. Fh=The strobe tran-

 

sitions latest.

 

 

 

 

20

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AMD 8151 1514, Pctl, 1Fh, then 1Fh is applied 11b, Updated by the hardware approximately every 8 microseconds
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8151 specifications

The AMD 8151 is a notable member of AMD's family of chipsets, designed to complement the AMD K5 and K6 processors. Released in the late 1990s, this chipset was primarily targeted at performance-driven PCs. The AMD 8151 provided users with an array of features and technologies that enhanced the overall computing experience, making it a popular choice among system builders and enthusiasts at the time.

One of the standout features of the AMD 8151 is its support for a 64-bit data bus. This significant design choice allowed for faster data transfer rates and better communication between the CPU and other critical components, such as memory. The chipset was capable of supporting multiple memory configurations, including ECC (Error-Correcting Code) memory, which enhanced system reliability, particularly for servers and workstations.

In terms of connectivity, the AMD 8151 included several integrated controllers, such as the PCI controller, which facilitated connections to various peripherals and expansion cards. With its support for the PCI bus, users could take advantage of high-speed devices, such as graphics cards, sound cards, and network adapters, enhancing the overall functionality of their systems.

Another important characteristic of the AMD 8151 is its power management capabilities. The chipset featured advanced power management technologies, which allowed systems to use energy more efficiently. This not only helped reduce operational costs but also contributed to less heat production, extending the longevity of the components within the PC.

The AMD 8151 also offered robust support for a range of bus speeds, which provided flexibility for users looking to customize their systems. With a maximum bus speed of 66 MHz, it was well-suited for the processors of its time, ensuring compatibility and optimal performance.

Moreover, the AMD 8151 played a crucial role in the development of 3D graphics capabilities. It was designed to work seamlessly with AMD's 3D graphics technology, which allowed for improved visual performance in gaming and multimedia applications. This made it an appealing choice for users who prioritized graphics performance.

Overall, the AMD 8151 chipset embodied the technological advancements of its era, providing enhanced performance, flexibility, and reliability. It stood as a testament to AMD's commitment to innovation in the computing space, marking a significant chapter in the evolution of PC architecture.
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