NAME

mem, kmem, mbmem, mbio, vme16, vme24 − main memory and bus I/O space

SYNOPSIS

None; included with standard system. 

DESCRIPTION

These devices are special files that map memory and bus I/O space.  They may be read, written, seek’ed and (except for kmem) mmap(2)’ ed.

Mem is a special file that is an image of the physical memory of the computer.  It may be used, for example, to examine (and even to patch) the system. 

Kmem is a special file that is an image of the kernel virtual memory of the system. 

Mbmem is a special file that is an image of the Multibus memory of the system.  Multibus memory is in the range from 0 to 1 Megabyte. 

Mbio is a special file that is an image of the Multibus I/O space.  Multibus I/O space extends from 0 to 64K. 

Vme16 is a special file that is an image of the VME 16-bit address space, extending from 0 to 64K. 

Vme24 is a special file that is an image of the VME 24-bit address space, extending from 0 to 16 Megabytes.  The VME 16-bit address space overlaps the top 64K of the 24-bit address space. 

Mbmem and mbio can only be accessed in Multibus based systems; vme16 and vme24 can only be accessed in VME based systems. 

When reading and writing mbmem and mbio odd counts or offsets cause byte accesses and even counts and offsets cause word accesses. 

FILES

/dev/mem
/dev/kmem
/dev/mbmem
/dev/mbio
/dev/vme16
/dev/vme24

Sun Release 2.0  —  Last change: 15 October 1984