Hi there, I am a newbie to PIC microcontrollers and need help with PIC
programmer. Recently, I have built David Tait's serial port programmer
[serpic] for the PIC16F84.   However, it only worked with certain PCs.
To tally up the current results, it worked with:

        1) 486 systems running Windows 3.1  (school)
        2) 486 90MHz systems running Windows 95 (school)

No luck with:<

        1) Pentinum 100MHz running Windows 95 (school)
        2) Pentinum 133Mhz running Windows 95 (home)
        3) 486 60MHz systems running Windows 95 (home)

I am using David Tait's prgramming software (MS-DOS) "SPP".
My programmer passes the Debugging test (toggling of RB6, RB7)
on all systems.  However, after burning the program, the verification
function fails on several systems.  To have total access to my COM1
port, I have restarted the PC under MS-DOS mode.  Current, I am using
David's batch file format to make programming commands more convenient.

batch file: myspp.bat

        [
                @echo off
                set ppsetup=s1
                set ppcom=1
                spp -xn %1 %2 %3

        ]

Then, in the DOS prompt, I type: myspp -xn walk.hex
For verification, I use myspp -v walk.hex
I could have omitted the -n so that verification is immediate.
Could anyone give me some help with this.  I don't understand why
the programmer is so system dependent?  I have friends who tells me that
the programmer works on his Pentinum system, whereas with mine, it
doesn't.  Your help is greatly appreciated.  Thanks.

Tam