Thanks Derek and Craig.

I did write a little BASCOM program to test those memory locations, and they appear to work correctly (see output below). I'm thinking somehow that one of the program's stacks is maybe pointing to a part of RAM the program is trying to use somehow. I'm pretty sure its something wrong with the board, given that it is a cheap board. I had a similar problem with another board (which used parallel port for programming vs. the serial port) where programs longer than about 1k failed to work. They always passed the verify step, but even so I found the ISP was not working correctly because when I switched from the Windows to the DOS version of the ISP program it started working. And I tried several other times with other programs and got the same results. I went to the company's website that makes the board to report the problem and found it was all in Chinese - no English version available. I feel there is probably a way around the problem I'm having with this board too. If I get some time this weekend I'm going to try breadboarding a circuit of my own using an AT89S8252 I have a spare of and some external RAM.

At least no one saw anything obvious that I was doing wrong. I thought at first I must be doing something stupid.

Thanks again for your help. I will post what I find once I build or buy a different dev board. I may also look into purchasing 1.3.

Frank Kienast

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'RAMTest.bas - Test external ram
'Appears there is a problem just above address 512 based on bas52 problems
'Written by Frank Kienast July 3, 2003
$CRYSTAL = 36864000
$BAUD = 9600

Out 513 , 0 : Print "513=" ; INP(513)
Out 514 , 0 : Print "514=" ; INP(514)
Out 515 , 0 : Print "515=" ; INP(515)
Out 516 , 0 : Print "516=" ; INP(516)
Out 517 , 0 : Print "517=" ; INP(517)
Out 518 , 0 : Print "518=" ; INP(518)
Out 519 , 0 : Print "519=" ; INP(519)
Out 520 , 0 : Print "520=" ; INP(520)

Out 513 , 255 : Print "513=" ; INP(513)
Out 514 , 255 : Print "514=" ; INP(514)
Out 515 , 255 : Print "515=" ; INP(515)
Out 516 , 255 : Print "516=" ; INP(516)
Out 517 , 255 : Print "517=" ; INP(517)
Out 518 , 255 : Print "518=" ; INP(518)
Out 519 , 255 : Print "519=" ; INP(519)
Out 520 , 255 : Print "520=" ; INP(520)


End

Output:
513=0
514=0
515=0
516=0
517=0
518=0
519=0
520=0
513=255
514=255
515=255
516=255
517=255
518=255
519=255
520=255