How address ''Long'' RAM ?

[user]

Posted on September 21, 2004 at 04:01

How address ''Long'' RAM ?

[user]

Posted on September 17, 2004 at 13:46

Hi to all,

I'd like to know how I can address the ''Long'' RAM (ST7 Lite19 from 0100 to 017F, on Memory Map-->16-bit Addressing RAM).

I tryed with :

LD X,$01

LD A,($FF,X)

but the ST Visual Develop send me a message with (no existent

memory at address 0x0100).

Is the same with :

LD X,$00

LD A,($0100,X)

Many tanks

MKBS

[wolfgang2399]

Posted on September 20, 2004 at 07:18

Please have a look at the datasheet at chapter

3 REGISTER & MEMORY MAP

There you'l finde the text :

The available memory locations consist of 128

 

bytes of register locations, 256 bytes of RAM, 128

 

bytes of data EEPROM and 4 Kbytes of flash program

 

memory. The RAM space includes up to 128

 

bytes for the stack from 180h to 1FFh.

 

.....

 

IMPORTANT: Memory locations marked as “Reserved�

 

must never be accessed. Accessing a reseved

 

area can have unpredictable effects on the

 

device.

You can't use the reserved area from 100 to 1FF. But if you need more RAM it is possible to address the unused (!) part of the so called 'stack' area e.g. from 180 to 19F.

Regards

WoRo

[sjo]

Posted on September 20, 2004 at 07:24

Make sure you have a 16bit ram section defined, eg.

WORDS

; don't alocate all 16bit ram, save some for the stack

segment byte at 180-1A0 'ram'

; define some data bytes

segment 'ram'

.test DS.B 1

then use the data

clr A

ld test, A

Regards

sjo

[ This message was edited by: sjo on 20-09-2004 10:57 ]

[user]

Posted on September 21, 2004 at 04:01

Many tanks to all !!!!!!!

MBKS