MEM(4spp) RISC/os Reference Manual MEM(4spp)
NAME
mem - memory pseudo-device
SYNOPSIS
{
"mem", nulldev, memopen,
memstrategy, nulldev, nulldev,
DTTYPECHAR,
DTFSNONE, "memory pseudo-device"
}
DESCRIPTION
Mem is a pseudo-device which allows commands that normally
operate on devices to transfer information to and from
memory. The mem device can be used to dump the contents of
memory to tape or load firmware from tape to a VME peri-
pheral which has address space on the VME bus. The mem dev-
ice is referenced as:
mem(baseaddr,width,addressmodifier)
Baseaddr specifies the base address of the transfer to or
from memory relative to the requested address space speci-
fied by addressmodifier. Width can be 1, 2, or 4 to
request byte, short, or word transfers from the indicated
memory space. Addressmodifier indicates the appropriate
address space to use when performing the transfer. If
addressmodifier is non-zero, it specifies a VME bus address
modifier to be generated. The CPU board can generate
address modifiers 0x9, 0x29, 0x2d, and 0x3d on the VME bus,
these are the only non-zero address modifiers that are
legal. If addressmodifier is zero, addresses are in the
R2000 address space; i.e. 0 is the base of KUSEG, 0x80000000
is the base of K0SEG, 0xa0000000 is the base of K1SEG, and
0xc0000000 is the base of K2SEG. See MIPS RISC Architecture
for a description of the R2000 address space.
DIAGNOSTICS
unsupported address modifier
An address modifier other than 0, 0x9, 0x29, 0x2d, or
0x3d was specified.
illegal width
A width other than 1, 2, or 4 was specified.
base address outside region
The base address specified is large than the size of
the address space specified by addressmodifier.
SEE ALSO
MIPS RISC Architecture
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