This program is a simple machine language monitor/debugger I hope you might find usefull in your machine language programming. The program itself is a Microbee adaption (with some improvements) of the monitor presented by Les Bell in his series of articles on "Understanding Assembler", which were presented in YOUR COMPUTER in 1982/83. The program is located in memory between 0400H and 09EAH, and can not be used when WORDBEE is in place (because WORDBEE has some important scratchpads in this section of memory and any attempt to load this program with WORDBEE in place will result in a jump to WORDBEE). The machine code file of this program auto-starts from BASIC, but can be loaded under the EDASM or WORDBEE monitors and run by typing G 0400 <RETURN>. When run the program presents you with an introduction and the cursor, which is a full stop (.) .
The commands are as follows;
(1) B xxxx :This command sets a breakpoint at location xxxx, which, when encountered while running the program you are debugging, causes a jump back to BEEMON, where the current values of the registers (before the breakpoint) are displayed. The Flag register is displayed with the bits either on (ie: 1) or off (ie: 0). To resume to the running of your program, issue the R command (described below).
(2) D xxxx,yyyy : This command causes the values of the memory locations between xxxx and yyyy inclusive to be displayed on the screen. The format is; the number of the memory location, followed by the values of this location and the next 16 locations in Hex, followed by the values of the same 16 memory locations in their corresponding ASCII representation (usefull for searching for strings and messages) and so on until the memory location yyyy has been displayed. Any control characters are printed as blanks in their ASCII representations.
(3) E : This just returns you to BASIC.
(4) H : This command is a help command which causes the commands of BEEMON to be printed on the screen.
(5) G xxxx : This command causes you to Go (ie:run) to the machine language program at address xxxx.
(6) R : Issuing of this command is carried out after a breakpoint has sent you to BEEMON (and the register values printed on the screen etc). It causes the program you are debugging to continue executing from the location where the breakpoint was set.
(7) S xxxx : This command allows you to begin entering/substituting values into memory starting at location xxxx. When issued BEEMON will print the current contents of xxxx on the screen. If you wish to change this then just enter the 2 Hex digits you require and hit <RETURN>. If you don't wish to alter this memory location then just hit <RETURN>. After either of these has been carried out then the next memory location is displayed, and you can do the same as before. To stop substituting memory locations and return to the main command level just enter a full stop instead of 2 Hex digits (or <RETURN>) and hit <RETURN>.
All of the above commands require a <RETURN> after them to be carried out. When entering commands you can backspace using the <BACK SPACE> key or by CTRL H, but not using the <DEL> key. If you really muck the whole command line up then the entire line can be deleted using CTRL X.
There is no tape commands (ie:save or load memory etc) or block move or compare commands as both the EDASM and WORDBEE monitors provide these. To use any of these commands from BEEMON just jump to the monitor using the BEEMON command G C003 and carry them out as usual. To get back to BEEMON just issue the EDASM monitor command G 0400.
The EDASM source listing of this program contains few comments, so to see how it works I refer you to the origonal articles in YOUR COMPUTER. I am willing to answer any general questions about this program if I can.
Ian D. Jolly, 13/9/83 &σ═w)&σ!ùσ═╡╤╤╤╤*d σ~#foσ═Mb ╤δßs#r═\δ═|╡
