[sdiy] Problems with AT90S8535 ISP Interface

[carsten at analog-monster.de]

Hi list,

could anybody please help me?

I built a testboard for a AT90S8535 with the simple ISP Interface from 

http://www.qsl.net/ba1fb/

(PC parallel port with four resistors to MISO, MOSI, SCLK and RESET) and
tested it with the Ponyprog software which I installed on my Windows 98
PC.

Everything works fine.

But then I testet all with my Windows 2000 Laptop, and the ISP interface
does not work. The Ponyprog software reportet connection test failed. I
made some tests with inverting signals, but no changes at all. 

One obvious difference between the Win98 PC and the W2K Laptop is that
the target device connected to the PC is permanently resetted until
programming starts and if it is connected to the Laptop the target
device is not resetted.

Questions:

Might there be a difference in Port Voltages / Currences between PC and
Laptop, so should I take away some resitors or use other values?

Is there a pin conrolling software layer between Ponyprog and the
parallel port (firmware, operating system)?

Remark:

A printer connected to the Laptop works fine.

Thanks in advance for help!

Regards

Carsten
-- 
Analog-Monster!
Synthesizer DIY Project
http://www.analog-monster.de