OK, I am drained.. here is the last program. I have been experimenting with BYTE and WORD and notice they make the memory behaviour REALLY different.. In any event, I have noticed:

1. I can WRITE from 0-640 to memory
2. When I READ this back, it is all '0's..
3. When I ERASE it ($FFFF), and read it back it is all 65355..

I THINK somehow I am writing PAGES using the [x] brackets..(???) I want to write to SPECFIC memory locations.. but can't figure out the syntax for that. maybe that is why the data is all messed up? So I tried putting it in increments of 128.. still reading back '0'..

Anyway - here is the sample program that lets you write, read and erase from an external 24LC512... and get back zeros..

TG

------------------------

'on my DataLoggers I have 16F876 or 18F252 and 2x 24LC512.
'The following code is tested.
'could you give it a try and let us know what the result was?
' -----[ Fuses ]------------------------------------------------
@ __CONFIG _CONFIG1H, _OSC_INTIO67_1H
@ __CONFIG _CONFIG2H, _WDT_ON_2H & _WDTPS_128_2H
@ __CONFIG _CONFIG3H, _PBADEN_OFF_3H & _MCLRE_OFF_3H
@ __CONFIG _CONFIG4L, _LVP_OFF_4L & 0bfh ;_XINST_OFF_4L
'
' -----[ Includes/Defines ]---------------------------------------------------------
include "modedefs.bas" 'include serout defines

OSCCON=%01111000
DEFINE OSC 8
While OSCCON.2=0:Wend

SCL var PortC.3 ' I2C Clock
SDA var PortC.4 ' I2C Data
ROM con %10100000 ' address of chip1
ADDR VAR word ' ROM Location
portout var PortC.6
portin var PortC.7
Mode con 16468 ' 4800 Baud 8N1 for Monitor Port
Test var byte[21] ' Test Array
I2Cdelay con 10 ' Delay after I2Cwrite

Temp var byte
X var word
dta var word

CLEAR

Addr=100
loop:
SEROUT2 portout,Mode,[13,10,"** MCU started",13,10,13,10]
serout2 portout, mode, ["enter 1 to write data, 2 to read it, 3 to erase"]
serin2 portin, mode, [DEC1 temp]

select case temp
case 1
for X = 0 to 640 step 128
I2Cwrite SDA, SCL,ROM,X,[X],failw
Serout2 portout, mode, ["Read Address: ",#X," Data:",#X,10,13]
pause 10
next x
case 2
for x = 0 to 640 step 128
I2Cread SDA,SCL,ROM,X,dta,failr
Serout2 portout, mode, ["Read Address: ",#X," Data:",#dta,10,13]
next x
Case 3
for x = 0 to 640 step 128
I2Cwrite SDA,SCL,ROM,X,[$FFFF],failw
Serout2 portout, mode,["Erasing Address: ",#X," Data:",$FFFF,10,13]
pause 10
next x
case else
goto loop
end select

goto loop:

failr:
serout2 portout, mode,["failure to read",10,13]
return

failw:
serout2 portout, mode,["failure to write",10,13]
return

END