exidysorcerer.net

1. Somewhere to connect ground during calibration and testing would be useful. Say a 1.6mm diameter hole between R6 and C4 where you could mount a nice test pin such as linked below or at least a loop of wire. That gives you a free hand to hold either the board or a screwdriver :D I like this style ...

As a postscript the Series Resonant Oscillator Circuit on this page by Thomas Scherre is a useful reference to the circuit topology of the 4MHz oscillator on the original Dreamdisk.

http://www.z80.info/uexosc.htm

P.S. And yes you can SAVE files:

In the image below the lower trace is a clean 2MHz signal and the top is what I was getting as input to pin 36. Do you mean pin 24 on the WD2793? Pin 36 is WPRT*, not the clock. Just want to confirm. Yes pin 24 sorry. Pin 36 is 4 pins from other corner :oops: Is the graph you are showing the oscill...

I've done more work comparing the write behaviour of the original and new boards. On both boards I could see the Write Gate go active low and the controller emit a string of negative going Write Data pulses to the drive. Even after checking the Write Precompensation timing again in the test mode I c...

Hi John,

I've swept the 5K pot R6 in minute increments from fully CCW that gives a WPW of 525nS through to fully CW that gives a WPW of 39 nS and I have not found a value that causes writes to succeed.

I will keep looking for other differences in setup or behaviour.

Here is one Write Data pulse on the original Dreamdisk board from the 80's. You can that the duration of the pulse is 450nS. I find the documentation ambiguous about how you adjust the width of the Write Data pulse. Page 8 of the TI manual for the WD2793 says that: "Write data consists of a ser...

I have connected up an original DreamDisk and "Gender Bender" board that was given to me by Altomare in Paris last year. I can read and write to a Gotek and successfully format a physical floppy with no errors. Pretty impressive considering no adjustments were made to any variable caps or ...

I have installed 7406 and 7407 parts in place of those from the LS family and saw activity on drive select. However I realise that since the drive select lines (in fact all outputs) are open collector and so you need them pulled high by a drive jumpered at that "address" in order to see th...

Thanks Leslie, The 74LS06 that provides output for driving step, direction, write data and write gate tests OK using the chip test function in an XGecu Pro T48 Programmer. Functionally step and direction (at least) seem to work fine to read data off the two built instances of the recreated board run...