Technical data

Device Support on OpenVMS Systems
7.11 Memory Holes on AlphaServer 4100 Systems
int dma_size;
int pages;
status = IOC$NODE_DATA (crb, IOC$K_DIRECT_DMA_SIZE, &dma_size);
/* dma_size contains the number of megabytes.
* convert number of megabytes to bytes.
*/
dma_size = dma_size * (1024 * 1024);
/* Convert number of bytes to number of pages by
* dividing by number of bytes per page.
*/
pages = dma_size / MMG$GL_PAGE_SIZE;
3. Compare the resulting number of pages with mmg$gl_maxpfn + 1.
4. If mmg$gl_maxpfn + 1 is greater than the size returned from IOC$NODE_
DATA, use map registers; otherwise use the direct DMA window.
7.12 SYS$MSBDRIVER Removed from OpenVMS Alpha Distribution
V7.0
The driver for the Microsoft Windows Sound System ISA sound card (MSB),
SYS$MSBDRIVER, has been removed from the OpenVMS Alpha distribution as
of Version 7.0. The following files have been removed:
• SYS$LOADABLE_IMAGES:SYS$MSBDRIVER.EXE
• SYS$EXAMPLES:SOUND_SERVICES.C
• SYS$EXAMPLES:SOUND_SAMPLE.C
• SYS$EXAMPLES:SOUND_SAMPLE.SND
• SYS$LIBRARY:SYS$STARLET_C.TLB module MSB.H
An enhanced version of this driver, called MMOV$MSBDRIVER, is included
in Multimedia Services Version 2.0 for OpenVMS Alpha. This layered product
also includes support for video capture and playback, an enhanced version of
DECsound, and other audio and video applications.
MMOV$MSBDRIVER provides the same $QIO programming interface as
SYS$MSBDRIVER. Compaq recommends that the WAVE Applications
Programming Interface provided by Multimedia Services for OpenVMS be
used instead because it is more flexible and is portable to other platforms.
(Multimedia Services Version 2.0 for OpenVMS is described in SPD 64.24.00.)
7.13 Device IPL Setup for OpenVMS Alpha Drivers
V6.2
Alpha hardware platforms that support PCI, EISA, and ISA buses deliver I/O
device interrupts at different IPLs, either 20 or 21. The IPL at which device
interrupts are delivered can change if you move the device from one platform to
another. This is a problem if the driver declares its device IPL to be 20, and then
that driver is executed on a machine that delivers I/O device interrupts at IPL
21.
The simplest solution to this problem is for PCI, EISA, and ISA device drivers to
use IPL 21. This works correctly on platforms that deliver I/O device interrupts
at IPL 20 and on platforms that deliver I/O device interrupts at IPL 21.
A future release of OpenVMS Alpha may provide a platform-independent
mechanism for drivers to determine the device IPL dynamically.
Device Support on OpenVMS Systems 7–9