DMON

A very competent machine code monitor and disassembler.

Runs in less than 3K of RAM using the top of memory &7000 thereby allowing large programs to be worked on.

Suitable for disc (40 and 80 track) and tape system.

All current Mode B configurations catered for (inc. Econet).

No special arrangements are required, e.g. setting PAGE as DMON will load and run above your existing program.

Memory dump and disassembled hex output to screen or printer.

Features

1. Test a subroutine - individual bits of status registers displayed
2. Run machine code from current location
3. Switch between paged roms
4. Hex dump with ASCII conversions
5. Move block of memory to a new location
6. String search
7. Examine ROM and move areas of interest to RAM location to be worked on or saved to disc or tape
8. DMON can be run by calling &7000
9. All Operating System commands available from the command line

Commands

@ - (Followed by hex digits) moves to that address
M - Moves block of memory to specified address
L - Hex and ASCII dump of memory from current address
R - Runs a machine code program from current address
D - Enters disassembler from current address
Q - Returns to Basic unless another Rom is selected
S - Test machine code subroutine (must contain a RTS) and allows setting of registers
R - Allows switching between Roms
E - Allows the editing of any address
H - Performs a string search

Space Bar - Moves forwards in memory one byte at a time or pages at a time in the disassembler/hex dump

Return - Moves the listing back one byte or exits the disassembler/hex dump

Instructions

DMON is probably the best machine code monitor and disassembler yet produced for the BBC Model B. It will run on any machine with a 1.0 or greater OS. The program occupies just over 3K Ram at the top of memory (&7000 onwards) which allows the disassembling of large programs.

DMON is screen independent, featuring instant loading from disc (40 and 80 track available) and is only nine blocks long from tape. No workspace is required and all Model B memory configurations are supported with no page setting required. DMON will load above your existing program.

As this program is written entirely in machine code, it is totally independent of any paged Roms present and will jump back to either Level I or Level II basic.

All commands within DMON are mutually implied and therefore there are no menus in which to get lost and confused. The ease of operation makes this particular program a must for any serious work on the BBC Model B.

Machine code routines can be executed from any particular address (provided the routines have an RTS) and so DMON becomes very useful for subroutine testing.

DMON will disassemble code in any part of memory and gives full hex, decimal and ASCII dump to screen with an optional hex and ASCII dump to printer if required. In fact, any specified part of memory can be dumped to printer.

DMON is especially valuable as a programmer's aid because the value in any location in memory can be changed instantly. Memory can be stepped forwards or backwards in order to examine bytes in Hex, ASCII or decimal values. Specific settings of the X,Y,A and Processor registers are easily accomplished along with an on-screen display of these register values upon completion of the program/subroutine run. DMON automatically resets HIMEM to &7000 and so Basic programs will run without the corruption of DMON. Any block of code can be moved to any other part of memory including code within paged Roms.

DMON will look at any Rom present in the machine giving full disassembly, move this block of memory into rAM with option to dump to printer/disc or tape. DMON allows switching between Roms at will.

Superior Systems ask you to note the considerable effort and commitment made in developing and presenting this software for your maximum convenience and that the copying of this program, for other than security reasons, or using it to copy other software, is a violation of copyright.

Loading

Tape: CHAIN"" (RETURN)
Disc: CHAIN"" (RETURN)

Use Space bar to load main program.

Note: Model B BBC Microcomputer Operating Systems 1.2 upwards