Atari 130XE Uživatelský manuál stáhnout pdf (Strana 33)

3.2 Debugger

The byte sequence can consist of up to 8 bytes, which is more than suﬃcient in most

cases. It’s also possible to omit bytes from the sequence. These bytes are ignored by the

search.

/1000/8D,,D4

will ﬁnd the ﬁrst address starting from $1000 that contains the

command “STA $D4xx” to write a byte into the ANTIC.

The byte sequence can also contain a bit mask. To do this, the separator

followed

by a bit mask must be appended to the byte, like for example

03&0F

. The content of the

memory will combined with the bit mask using AND and will then be compared with the

byte value from the byte sequence.

If an end address is speciﬁed in addition to the start address, all addresses where the byte

sequence is found are printed. That means the search does not stop at the ﬁrst occurrence

when entering for example

/start,end/value1,value2...

. Many times, the complete

memory is to be examined. Therefore there is the very short variant

//value1,value2...

which is identical to /0000,FFFF/value1,value2....

If the byte sequence is long or the memory area is large, the search may take several

seconds. Using the

[BREAK]

key, the search can be interrupted at any time. It can then

be resumed with the / command.

3.2.8 Execute SIO commands

The commands

SIO

as well as the built-in DOS use an internal sector buﬀer. The

memory manager mirrors it to the address $D700 in the frozen address space, where it can

be edited by the debugger. Physically it is not present at that address. To read a sector

from a diﬀerent drive than

D1:

or to write it there, just prepend the sector number with

Dx:.

SR 100

SR D2:200

SW D3:300

With the

SIO

command, arbitrary commands can be sent to the SIO, just like using

the SIO vector $E459. The values have the same meaning as the memory locations

$0300. . . $030B in the Atari. The maximum allowed value for length is $0100.

SIO device, unit, command, direction, timeout, length, daux

The

SIO

command retains the parameters of the previous execution, so they can be

omitted in the next

SIO

command. If all parameters are omitted, the last

SIO

is repeated.

At the beginning, the parameters are set to “Get Status” for

D1:

, so nothing wrong can

happen in case SIO is entered without parameters.

In any case the

SIO

should always be used with caution and the parameters should be

verﬁed thoroughly, because otherwise formatting the wrong disk may happen quickly.

3.2.9 Display interrupt and VCOUNT

The freezer can freeze the running program when an interrupt occurs. To this end the

freezer reroutes the interrupt vector and thereby forces the CPU to enter the freezer. The

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