Data General NOVA 4/S Manual page 23

Cell Commands
To open a cell, use one of the commands listed in Table
2.2. VC will respond only to octal numbers and upper
case letters. In the table, the term current cell means
the last cell that you opened.
When you open a memory cell, VC interprets the
address as a 17-bit physical address. You do not have to
type leading zeroes. All you have to type is the physical
address in octal representation. For example, if you
want to open location 5, type 5/. If you want to
examine the top location of a NOVA 4/X system which
contains 256K bytes of memory, type 377777/.
Command Function
equal to n. (Refer to Table 2.1 for the internal cell
n/ Open the memory location whose address is equal to
cell.
Close the current cell, but do not open another.
New Line) ,
/ Ciose the current cell and open the memory cell whose
address is equal to the contents of the current memory
or internal cell.
Once you have opened a cell, you may change its
contents by simply typing (in octal) the number whose
value is to be placed in the cell. Terminate the
expression with a Carriage Return, Line Feed or New
Line. Note that if you type Carriage Return the next
cell will also be opened. This is convenient when you
need to enter data into several consecutive locations.
Table 2.3 below lists the VC function commands. All
commands must be typed in octal numbers and upper
case letters.
VC has two commands to start program execution.
Typing P starts program execution at the location
specified by internal cell number 4 (the return address).
You can also start program execution by typing nR. In
this case, the CPU issues an I/O Reset command, clears
the MMPU, and starts program execution at the location
specified by the octal number n.
Typing I causes the CPU to issue an I/O Reset
command and clear the MMPU.
13
specified by the contents of internal cell number 4 (See
Issues an I/O Reset; clears the MMPU (NOVA 4/X
only), and starts program execution at the memory
location specified by the octal number n.
device, and is a 1 for a high-speed device.
You can program load from an I/O device by typing nL
where n is the device code, in octal, of the I/O device
to be used. Bit 0 of n should be a 1 if the I/O device is
high-speed, and a 0 if the I/O device is low-speed. For
example, if the program load device is a high-speed
6060 disc drive whose device code is 27, you would type
the following:
100027L
You can perform a Data General field service cassette
bootstrap load by typing F.
Virtual Console Errors
If you type a character that VC does not recognize, it
will print a ? followed by a New Line. If you wish to
cancel an entire line you just entered, type a K. In this
case VC will respond with a? followed by a New Line.
If you attempt to open a non-existent memory cell, the
16-bit contents of the cell printed in octal on the
terminal will be all 1's. You can verify that this
location does not exist by entering a new value
containing 0's in the cell and then re-opening it. If it
still contains all 1's, the location is non-existent.
If you attempt to open a non-existent internal cell, the
contents of the cell printed on the terminal will be
random and meaningless data.