Hi all,

This is my first post.
I have a problem with a 89C51RD2 chip. I\'m using only the internal RAM of this chip.
The chip is driving a Toshiba graphic display which uses A15 as CS.
Another line (A11) is used as C/D for the display. This line determines if a command or data is send.
So it\'s kinda memory mapped to the displayand only uses the adresses 8800 hex and 8000 hex. I don\'t use a latch because it\'s only needed for the low byte of the 16 adress word and I don\'t use that. I only use it as databus.

When I try to contact the display at &H8000 or &H8800 nothing toggles on A15 or A11. All the data lines are \'dead\' too.

I\'ve checked the datasheet and came up with this info.
- When accessing external memory P0 and P2 have internal pullups. So none are required external.
- When using an adress higher then the upperadress of the internal ram automatically adresses the external ram
- There is register called AUXR. Bit 1 determines external or internal memory use.

I\'ve experimented a lot with the above but everytime with the same result. Nothing toggles not even with the display disconnected.
I use Bascom 8051 which I succesfully used to drive the display using a normal 8051,latch and eprom config.

Does anyone have a solution? I\'ve checked the entire maillist but couldn\'t find anything simular.

thanks in advance for your time,
Regards,

Peter
The Netherlands