User`s guide

2–18 Getting Started
Downloading Files
2.6.2 DMA Buffers
Various devices used with the motherboard require direct memory access (DMA).
The device drivers provided in the Debug Monitor for these devices are designed to
perform their DMA within a 1MB range starting at 1 megabyte (physical address
100000
16
). At startup, the Debug Monitor initializes the I/O subsystem with DMA
windows that include this range. The device drivers included with the Debug
Monitor that require DMA are the Ethernet and diskette drivers. Although the ebuff
command can be used to change the base of the Ethernet buffers, the buffers must
remain within this 1MB window.
2.7 Downloading Files
The motherboard supports loading files into memory from a serial port, the Ethernet,
and a diskette. The user can either load the file into memory, or load and execute the
file in a single step. The following table shows the commands for the specific I/O
devices. See Chapter 4 for more details about these commands.
The default boot address (bootadr) is 300000
16
. However, you can change the default
boot address with the bootadr command. The new setting is then stored in the
battery-backed RAM.
2.8 Execution Commands
After your program is loaded, you are ready to execute it. If the command loads and
executes a program, you may want to re-execute the program during the
motherboard session. The Debug Monitor has two commands to execute programs:
go and jtopal. See Chapter 4 for more details about these commands.
I/O Device
Use this command to
load into memory...
Use this command to
load into memory and execute...
ROM socket romload romboot
Serial port load boot
Ethernet netload netboot
Diskette flload flboot