Motorola MVME197LE manual Address as a Parameter, Address Formats, Offset Registers

Using the 197Bug Debugger

Address as a Parameter

Many commands use ADDR as a parameter. The syntax accepted by 197Bug is similar to the one accepted by the one-line assembler. All control addressing modes are allowed. An “address + offset register” mode is also provided.

Address Formats

4Addresses are entered as a hexadecimal number, e.g., 20000 would correspond to address $00020000. The address, or starting address of a range, can be qualified by a suffix of the form ^S, ^s, ^U, or ^u, where S or s defines Supervisor address space, and U or u defines user address space. The default, when the qualifier is not specified, is Supervisor.

Once a qualifier has been entered, it remains valid for all addresses entered for that command sequence, until the 197Bug is re-entered or another qualifier is provided.

An alternate form of Address is Rnn, which tells the bug to use the address contained in CPU Register Rnn, where nn=00 through 31 (i.e., 00, 01, ..., or 31).

Hence ADDR:= Hex Number{[^S][^s][^U][^u]} Rnn

		In commands with RANGE specified as ADDR DEL ADDR,
N
	ote
		and with size option H or W chosen, data at the second
		(ending) address is acted on only if the second address is a
		proper boundary for a half-word or word, respectively.
		Otherwise, the range is truncated so that the last byte acted
		upon is at an address that is a proper boundary.

Offset Registers

Eight pseudo-registers (Z0-Z7) called offset registers are used to simplify the debugging of relocatable and position-independent modules. The listing files in these types of programs usually start at an address (normally 0) that is not the one at which they are loaded, so it is harder to correlate addresses in the listing with addresses in the loaded program. The offset registers solve this problem by taking into account this difference and forcing the display of addresses in a relative address+offset format. Offset registers have adjustable ranges and may even have overlapping ranges. The range for each offset register is set by two addresses: base and top. Specifying the base and top addresses for an offset register sets its range. In the event that an address falls in two or more offset registers' ranges, the one that yields the least offset is chosen.

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