Atari 130XE Bedienungsanleitung PDF herunterladen (Seite 31)

3.2 Debugger

Remark: With the exception of the spaces immediately following the command, all

spaces in the above list are only there for readability and must not be entered with the

command. The program counter (PC) cannot be changed using

due to its special

handling. Use the G command to change its value.

3.2.3 Input of values (hexadecimal, decimal, internal code)

Addresses and byte values are input in hexadecimal notation by default. Use the percent

sign “

” as a preﬁx to enter an address or byte value as decimal number. The following

command corresponds to the statement “POKE 710,10” in BASIC.

C%710<%10

Byte values can also be given in ATASCII or internal Atari screen code. For ATASCII,

the single quote “’” must be used as preﬁx, for screen code the at sign “@” must be used.

C0600<’H,’a,’l,’l,’o

C9C40<@S,@c,@r,@e,@e,@n

3.2.4 Input of vectors

For working with vectors (

i. e.

display list or interrupt vectors) an additional variant for

specifying addresses is available. If the preﬁx “

” is used for an address, the 2 byte vector

at that address is evaluated and the content of the vector is used as eﬀective address. This

can be used for example to display the current display list very eﬀectively.

DL*230

DL*%560

3.2.5 Access to extended memory, RAM, ROM

The debugger oﬀers full control over the memory management functions of the Atari

XL/XE when accessing the memory content. The memory management unit is controlled

by the register

PORTB

($D301) of the PIA. This way it is possible to read and change

the content of the RAM extension ($4000. . . $7FFF) or the RAM under the OS ROM

($C000. . . $CFFF, $D800. . . $FFFF) without problems.

The

PORTB

control only refers to the access from within the debugger. Changes do not

aﬀect the frozen program. To change the state after resuming, the frozen content of

PORTB

must be changed using C D301<byte.

When the freezer is activated, the current value of

PORTB

is used as default for the

debugger. That means you see the same state in the debugger as the frozen program would

see. The PORTB control can be displayed and changed with the PB command:

PB Display current PORTB value

PB<value Set new PORTB value

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