User manual HP VECTRA 500 MODEL 515 VECTRA 500 SERIES PC, MODEL 510 (PENTIUM BASED), MODEL 515 - HARDWARE AND BIOS

[. . . ] HP Vectra 500 Series PC Models: 510 5/xx 515 5/xx Hardware and BIOS Technical Reference Manual February 1996 Notice The information contained in this document is subject to change without notice. Hewlett-Packard makes no warranty of any kind with regard to this material, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Hewlett-Packard shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material. Hewlett-Packard assumes no responsibility for the use or reliability of its software on equipment that is not furnished by Hewlett-Packard. [. . . ] Each table is identified by a unique type. The type is given by the first byte of the table. The length of the table is given by the second byte. The next table follows immediately after the current one. Each type of table has a pre-defined format. For a list of the major table types, refer to "DMI Sub-Structure Tables, " on page 35. 6 Use the pointer to retrieve string values. All string values are terminated by a null (zero) value. The DMI Header The DMI header is the starting point for all DMI information. Field DMI Header Signature Version DMI Header Length Pointer to DMI structures Length of DMI structures Checksum of DMI structures Checksum of DMI header 0h 4h 5h 0Ah 0Ch 0Ch 0Dh Offset Length 4 bytes 1 byte 1 byte 4 bytes (DWORD) 2 bytes (WORD) 1 byte 1 byte "$DMI" 00010010 (Ver 1. 2) 0Eh Far pointer (variable) variable variable variable Value 34 3 Desktop Management Interface Accessing BIOS DMI Information Verifying the DMI Information Structure Before accessing the DMI tables, the checksums must be verified to ensure the reliability of the information. To calculate a checksum value of a structure, do the following steps: 1 Add together all the bytes of the structure. 3 Cast the value to a byte (take the low byte). There are two checksums, one for the DMI header and another for the remaining DMI structure. To verify these two checksums, do the following steps: 1 Locate the DMI header. 2 Using the length value of the DMI header, calculate the checksum value for the DMI header. (When adding together the bytes of the header, exclude the checksum byte, offset 0Dh. ) 3 Verify this value against the checksum given for the DMI header. 4 Retrieve the position and length of the DMI structures. 5 Calculate the checksum value for the DMI structures. 6 Verify this value against the checksum given for the DMI structures. DMI Sub-Structure Tables Each type of table has a pre-defined format. Although the structure can evolve over time, new fields are always added to the end of the table and the length value reflects this new size. To parse several tables in order to find a specific table, simply use the table length. Using this method will ensure that the parser can function even when the tables evolve over time. To locate specific BIOS information, use the DMI sub-structure tables which are listed on the following pages. 35 3 Desktop Management Interface Accessing BIOS DMI Information Type 1 : BIOS Information Field Type Length Vendor BIOS Version BIOS Starting Address BIOS Release Date BIOS Characteristics BIOS ROM Size Offset 0h 1h 2h 6h Ah Ch 10h 14h Length 1 byte 1 byte 4 bytes (DWORD) 4 bytes (DWORD) 2 bytes (WORD) 4 bytes (DWORD) 4 bytes (DWORD) 1 byte 1 15h variable variable variable variable variable bit field variable Value Description BIOS information table Table length (in bytes) Far pointer to string containing BIOS vendor name. Far pointer to string containing BIOS version number. [. . . ] The video subsystem uses the PCI bus for data transfers between the processor and the video subsystem, and has the following features: · 100% compatible with IBM VGA display standard · 32-bit video memory access with 1 MB DRAM. This increases to 64-bit access when an additional 1 MB DRAM is installed · Hardware acceleration of graphical user interface (GUI) operations · Support for up to 2 MB DRAM at 60 ns · Graphics resolutions of up to 1280 x 1024 · Integrated 24-bit RAMDAC · Green PC power saving features · Standard and Enhanced Video Graphics Array (VGA) modes · DDC 1 compliant. Video Memory The S3 Trio 64 PnP integrated video subsystem has 1 MB of video DRAM preinstalled on the system board, and provide two sockets for the installation of a pair of 512KB video DRAM chips, giving a total of 2 MB video memory. 50 5 The Ultra VGA Video Controllers The Integrated Ultra VGA Video Controller Video Modes The video subsystem is responsible for generating video data (which is placed in video memory) to be sent to the display. The following table details the standard VGA modes which are currently implemented in the video BIOS. These modes are supported by standard BIOS functions; that is, the video BIOS (which is mapped contiguously in the address range C0000h to C7FFFh) contains all the routines required to configure and access the video subsystem. Standard VGA Modes Mode No. [. . . ]