October 30, 1997
11
The TCS coordinate window(under Options) can be used to center a source or move it around the
arrayat the 88-inch. Theplate scale defaults to the f/10 scale (0.1886 arcsec/pix), for the f/31 scale it
is 0.0608 arcsec/pix. First move to the sourceand press the “f" key, it will grab the pixel locationas
the “From"coordinates (you may need to click left with the mouse on the source before hitting the F
key). Then move to the center or whereverand hit the “t" key to grab the “To" location. Alternatively,
thefrom and to positions can be defined by holding the shift keyand clicking and dragging the middle
mouse button. Once the pos itions have been defined, click on “calculate offset" and then on “Offset
TCS" to actually move the telescope (the 88-i nch). You can also just read the offsets and move the
telescopeby hand.
8 QCDCOM commands
Thisis a descriptionof the available QCDCOMcommands. Anyunique abbreviation will work, and
qcdcom will prompt you if you enter an ambiguous command. When you first start qcdcom you
shouldbe awareof two self explanatory commands:
help Help help lists the currently recognizedcommands. Angle brackets indicate
arguments,and square brackets indicate optional arguments.
quit Quit quit terminatesqcdcom. Control-Dwill also do this.

8.1 DSPinitialization commands

In general, you will need to initializethe DSP processor in the Leach electronics after power-up or
after a DSP reset, because its cold-reset state is not appropriate for runningthe inst rument. In order
to do this you need to reada fileof compiled DSP code, and then download it to the DSP.(Note that
DSPassembler code in a .asm file is compiled by the a56 compiler into binary code in a .lod file. For
example, a56 quircop1 will read quircop1.asm andwrite quircop1.lod.)
Note that while you may see severaldifferent versions of the code for QUIRC in the dsp directory,
you can always find the current version of the code as quirc.lod. (Itis maintained as a symbolic
link to the working code.) Thus to download the current version of the code, after a power cycle
or DSP computer reset, you can always use df quirc to load correct code. Remember that it
is not necessary (and evenundesirable) to download code when qcdcom is restarted. Quitting and
re-startingqcdcom in itself has no effect on the on-board DSP computer, which runs independently.
df file Read and downloadDSP code
df is a combination of ll and dl, and is the normal command to use for sending
code to the DSP.It will fill in a .lod extension if it is missing, and it will look in
directories according to the environment variable LODPATH, which can be set to a list
of directories separated by colons. Thus, the visitor account has been provided with:
setenv LODPATH .:/aux/inst/dsp:./mydspcode
Example: df quirc