Sorry, I don't understand what you mean. I added resistors to +5 and GND, no buffers.Can you make a small schematic of your buffer stage ?
I'll trycan you take some oscilloscope pictures of the Write Data line synced on the Write gate line during sector writing ?
ok i didn't understand.schadel wrote:Sorry, I don't understand what you mean. I added resistors to +5 and GND, no buffers.Can you make a small schematic of your buffer stage ?
I'll trycan you take some oscilloscope pictures of the Write Data line synced on the Write gate line during sector writing ?
-b-
I borrowed a DSO. See the attached photos. The second photo shows that "data" begins to appear on WD about 180us after WG goes low.Jeff wrote:Another point : can you take some oscilloscope pictures of the Write Data line synced on the Write gate line during sector writing ?
Yes, see the drawing. A typical termination is 220 ohms to +5 (but I used 270 because of the 1K already on the emulator) and 330 ohms to ground. That equates to a termination impedance of about 129 ohms which is ideally near the impedance of the cable to minimize reflections but more importantly it is low enough to charge the cable capacitance quickly. The line driver is open-collector and requires an external pullup. The resistor network effectively connects it to +3V through 129 ohms. 3V is well above the logic "1" threshold, at least for TTL.So if understand well you have added a pull up and a pull down resistor ?
I connected it to an HP Vectra and after I learned to set the "File Interface Mode" in Settings to "IBM PC 1.44MB" before exporting to .hfe (I see that it sets a byte in the .hfe file), it worked. I was able to write to the emulator on the Vectra.Connect it on a PC and try to write something on a ms dos floppy disk image.
The write data input are in schmitt trigger mode. The minimum high voltage is 0.8*VDD=0.8*5=4V. 3.3V high voltage is too low.schadel wrote:I borrowed a DSO. See the attached photos. The second photo shows that "data" begins to appear on WD about 180us after WG goes low.Jeff wrote:Another point : can you take some oscilloscope pictures of the Write Data line synced on the Write gate line during sector writing ?
Yes, see the drawing. A typical termination is 220 ohms to +5 (but I used 270 because of the 1K already on the emulator) and 330 ohms to ground. That equates to a termination impedance of about 129 ohms which is ideally near the impedance of the cable to minimize reflections but more importantly it is low enough to charge the cable capacitance quickly. The line driver is open-collector and requires an external pullup. The resistor network effectively connects it to +3V through 129 ohms. 3V is well above the logic "1" threshold, at least for TTL.So if understand well you have added a pull up and a pull down resistor ?
I connected it to an HP Vectra and after I learned to set the "File Interface Mode" in Settings to "IBM PC 1.44MB" before exporting to .hfe (I see that it sets a byte in the .hfe file), it worked. I was able to write to the emulator on the Vectra.Connect it on a PC and try to write something on a ms dos floppy disk image.
I have been using the default Shugart File Interface Mode for the SORD and my 50-to-34 pin adapter follows the Shugart pinout. Does the File Interface Mode choice have any effect other than changing the pinout?
Thanks,
--Bruce--
That's a very high threshold! The Schmitt Trigger receivers (74LS19) on the mainboard (for RD, etc) switch at about 1.9V on a positive-going transition.The write data input are in schmitt trigger mode. The minimum high voltage is 0.8*VDD=0.8*5=4V. 3.3V high voltage is too low.
I will remove them.So i recommend you to remove the pull down resistor or if you prefer increase its value to obtain at least an high voltage of 4.5V.
It is 250 ns. But if you look at the first 'scope photo I posted, before adding resistors, you can see that without them the emulator would stretch it to ~500ns if it switches at 4V. (Maybe that's why it didn't work then?) It will be somewhere between if I keep the 270 ohm resistors to +5V.what is the write data pulse length ? 500ns ?
In fact the very first picture looks good enough to me. Don't forget that this is an open collector bus. the "slow" raise time isn't the problem here.schadel wrote:That's a very high threshold! The Schmitt Trigger receivers (74LS19) on the mainboard (for RD, etc) switch at about 1.9V on a positive-going transition.The write data input are in schmitt trigger mode. The minimum high voltage is 0.8*VDD=0.8*5=4V. 3.3V high voltage is too low.
I will remove them.So i recommend you to remove the pull down resistor or if you prefer increase its value to obtain at least an high voltage of 4.5V.
It is 250 ns. But if you look at the first 'scope photo I posted, before adding resistors, you can see that without them the emulator would stretch it to ~500ns if it switches at 4V. (Maybe that's why it didn't work then?) It will be somewhere between if I keep the 270 ohm resistors to +5V.what is the write data pulse length ? 500ns ?
It would be a problem to make the 50-pin cable shorter for several reasons. Perhaps I should add a receiver chip
to my adapter if I can find a pnp open-collector or CMOS one that will enable the output to go above 4.5V quickly (The 'LS19 won't do). Do you know the threshold for a low-going transition?
merci beaucoup,
--Bruce--
1VDo you know the threshold for a low-going transition?
OK, I removed the pulldown resistors and left the 270 ohm pullups in place. Now I have a different error--WEOE. What does that mean? --Bruce--So i recommend you to remove the pull down resistor
schadel wrote:OK, I removed the pulldown resistors and left the 270 ohm pullups in place. Now I have a different error--WEOE. What does that mean? --Bruce--So i recommend you to remove the pull down resistor
No, I was just trying to create a small file.you got this during a formating ?
The whole file was only a few bytes that I typed, much less than one sector. The sector size in the image I was using is 256.Actually the emulator support only normal write sector , not a full track formatting.
mhh so there are a problem with the write gate line...schadel wrote:No, I was just trying to create a small file.you got this during a formating ?
The whole file was only a few bytes that I typed, much less than one sector. The sector size in the image I was using is 256.Actually the emulator support only normal write sector , not a full track formatting.
Thanks,
--Bruce--
new version. tell me what you get with this : (update process in the user manual).Jeff wrote:mhh so there are a problem with the write gate line...schadel wrote:No, I was just trying to create a small file.you got this during a formating ?
The whole file was only a few bytes that I typed, much less than one sector. The sector size in the image I was using is 256.Actually the emulator support only normal write sector , not a full track formatting.
Thanks,
--Bruce--
well, i got it... its a firmware problem. (write gate not correctly monitored at 500kbits...)
i will correct this as soon as possible.
thanks for your feedback.
mhh so there are a problem with the write gate line...
well, i got it... its a firmware problem. (write gate not correctly monitored at 500kbits...)
i will correct this as soon as possible.
Thanks, Jeff! I'll flash it tonight and try it tomorrow. --Bruce--new version. tell me what you get with this : (update process in the user manual).
https://hxc2001.com/floppy_drive_emulat ... 5_1_1A.UPD
Sorry, I get Error 404 on that link -b-new version. tell me what you get with this : (update process in the user manual).
https://hxc2001.com/floppy_drive_emulat ... 5_1_1A.UPD