Little background:
I've just started working with an 8052 (specifically the Dallas Semiconductor DS89C420). I've successfully connected a character LCD display and programmed it using c language (SDCC compiler).

I'm trying to access the internal 1K of SRAM on this chip which requires I set bit0 of the PMR register before I can use this memory. Well I've tried to do this both in C and ASM (I don't know much / any asm for the 8052) but I have yet to be successful in being able to write/read from this memory. I've also been unable to find any sample assembly code that does this. I have an aplication note from DS that shows a sample c code for this but I have not been able to produce working code from there sample (though there SDCC version was 2.4.0 and I have 2.5.0)

So my question is does anyone use this chip (or another from Dallas) and have experience using this internal SRAM? If so could you provide sample assembly code?

Below are two of my attempts to use the memory, if anyone sees any issues that might cause my problem please let me know.

test.asm
mem.c

ASSEMBLER: A51
COMPILER: SDCC 2.5.0

Also if anyone wants to see a real mess in wiring/prototyping look at the pics on www.partingc.com