Elektor EPROM Emulator flaky - continued

I use a parallel port PIC programmer and had problems under XP with the programming mode continually being reset (LED's flashing!). This registry hack fixed it for me. It seems XP continually polls the parallel port and this interferes with other uses.

[HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Parport\Parameters] "DisableWarmPoll"=dword:00000001

Please let me know if it cures your problem - I will add it to my list of "known cures" :)

Rick.

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Gee, the differences in the OS are likely the problem. XP requires you to use system calls to access any peripheral (port) and tries to guard against any program accessing the Ports directly. Frankly I do not know how to correct this. It is built into the OS.

I may be wrong. But this was the explanation I got when I tried to run a couple of my older programs under XP. I run them in the DOS mode now and they work. But I don't know anything about your download program, so your still short enough information to solve your problem.

In message , Captain Rick writes

As an aside to this, are you aware that most Laptops and many desktop machines are only 3.3v parallel ports.... if the interface on the Emulator isn't 3.3V compliant, it may also cause problems.

--
Clint Sharp

Thank you for all the useful responses, which I only managed to read on Monday morning!

Over the past weekend, I probed the Centronics STROBE line going into the emulator using an oscilloscope. Suddenly the code downloading process was more reliable whilst the 'scope was connected! I replaced the 'scope with a 10k resistor to ground and was able to download more consistently.

I would suspect that the 7407 buffer on the strobe line might be faulty, but I will first check out the registry setting issue as well as the 3.3V issue. I will feed back results ASAP.

To Clarence - I am using the DOS command line binary copy to LPT1 to load the object into the emulator.

Jack

Some feedback: I tried the registry setting change, but this did not have any effect. I checked the Centronics voltage levels from the laptop, and it seems they are indeed 3.3V levels. However, the 7407 specs indicate minimum high voltage of 2V, so it should be able to handle a STROBE line at

3.3V. I will replace the 7407 (and maybe also try out a 74LS07). Jack

I replaced the 7407 buffer with a 74LS07 buffer, but this did not have any effect.

I guess I will now have to fall back to putting a high value resistor between STROBE and ground (on the output side of the buffer) - this seems to have worked last time I tried it...

Any other recommendations would be appreciated...

Jack

I soldered a 10k resistor between the Centronics STROBE line (on output of 74LS07 buffer) and ground, and now code images are being downloaded into the emulator without problems.