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The PRIMER Trainer has twenty keys for input, with some keys having a second function which can be invoked using the
"FUNC." key. Each key produces an audible tone when pressed, providing feedback for the user.
KEY
DESCRIPTION
0-F
Numeric keys. When a numeric key (0-F HEX) is pressed, the numeric value appears at the right side of a
data field display and the number that was there before will be shifted left. To correct an entry error just
repeat, using the correct number key and the error will be overwritten.
Step
This key causes the microprocessor to execute one instruction (single step) at the current program
counter address (the value of the P.C. register). Single stepping is a valuable debugging tool that allows
the user to examine registers and memory after each instruction executes. The Step key executes the
instruction at the program counter address and then returns to the Monitor Operating System and waits for
another user command. When you single step a CALL instruction that is calling a subroutine in ROM
(such as a service call), the processor will execute the subroutine at full speed and stop at the instruction
immediately following the CALL instruction.
Dec.
This key decrements the program counter and shows the program counter in the left four displays and the
data at the program counter address in the right two displays.
Enter
&
Inc.
When the monitor is in the data entry mode, pressing this key stores the data that is on the two far right
displays into the program counter address then increments the program counter and displays the new
program counter address in the left four displays and the data at that address in the two far right displays.
This key is also used to store new values for the registers, the breakpoint and the stack content (see the
section below about second function keys). If the register, breakpoint or stack content information
displayed has been changed but you don't want to enter it, then simply press the "Func." key twice and the
original information is maintained. This key can also be used to just view data in memory.
Func. This selects the second function of the keys that have two functions. When this key is pressed "Func."
appears on the display, and if a key is pressed which has a second function, that function will be
performed. This key may be pressed two times in a row to exit the current mode and return to the data
entry mode.
( Below are the second functions of the keys with two functions )
B.P.
This key displays the current software breakpoint address. If 0000 is displayed, then no breakpoint has
been established. The displayed value may be changed by entering the desired breakpoint address in
hex using the numeric keys and then pressing the "Enter & Inc." key. When the program reaches the
breakpoint the software breakpoint address is automatically reset to 0000. NOTE: Obviously, if the
program execution never reaches the breakpoint address, the program will not stop at the breakpoint
address. If the breakpoint address points to a byte other than the op code in a two or three byte
instruction, the program will not stop at the breakpoint address. Also any address specified that
references addresses in EPROM (addresses below 8000 hex) will not stop execution, even if the op code
at that address is executed.
S.C.
This displays the 16 bits that are at the top of the stack, or in other words, the data that will be removed
from the stack with the next POP, RET or XTHL instruction. The two displays on the far left represent the
data at SP + 1 (stack pointer address + 1) and next pair to the right represent the data at SP. The
displayed value may be changed by entering the desired hex number using the numeric keys and then
pressing the "Enter & Inc." key.
A.F.
This key displays the contents of the A register (Accumulator) and the condition Flags. The A register and
the flags are displayed as four hex digits in the four displays starting at the left. The digit pair on the left of
the four displays show the value of the A register and the pair on the right show the value of the condition
Flags. The displayed value may be changed by entering the desired hex number using the numeric keys
and then pressing the "Enter & Inc." key. The condition Flags are defined bit by bit as follows:
APPENDIX B: The PRIMER Keypad Description
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