The bank number in the chart above is the value of the accumulator during a DCl instruction, needed to address that bank of RAMs. The port number given corresponds to the number typed out during simulation of the WMP instruction. Register positions
The Q directive is used to define and set aside some part of RAM for use by the simulation program as simulated ROM and other registers and parameters. Whole RAM registers are taken by the Q directive, beginning with the register identified in the first parameter. The status locations from exactly 12 registers are used by the simulator. The number of main memory locations used is determined by the difference between the second and third parameters of the Q directive. Where sand e represent the values in the second and third parameters of the Q directive, the number of registers used is determined by the
formula: n = (s + e}/8 + 1
This value may be more or less than 12, the number of registers whose status locations are used, with no ill effects.
RAM main memory locations reserved by the Q directive are used solely for program storage. The instruction with an address equal to the second parameter of the Q instruction is loaded into digits 0 and 1 of the register designated by the first parameter of the Q directive; subsequent instructions are loaded into the following digit pairs, according to the addresses.
The RAM status locations reserved by the simulation program are allocated to the following functions:
Relative |
|
|
REGISTER | lOC'N. | FUNCTIONS |
r + 0 | 0 | Simulated Accumulator |
0 | low ROM address limit | |
| 0 | Option word |
1 | High ROM address limit | |
2 | 0 | Execution parameters |
2 | Breakpoint address | |
3 | 0 | Simulated Carry |
3 | Simulation Cycle counter | |
4 | 0 | Simulated Stack pointer |
Simulated Stack | ||
5 | 0 | Simulated Command line selection |
6,7 | 0 | Simulated ROM or RAM chip selection |
Simulated index registers |
9.0EXAMPLES
Figures 9.1, 9.2 and 9.3 are annotated listings generated during actual simulation. Figure 9.1 is a simulation of the "ANO" program described in figures 9.4 and 9.5. Figures 9.2 and 9.3 represent the simulator's response to various directives entered via a TTY keyboard.
8
