If changed to HC, then the 47K will work just fine.

#memory #ELF

Thanks, Lee for the suggestion to substitute a 74C10 for a 74LS10. Since many of us have 74HC chips, what would be the consequence of substituting a 74HC10 for the 74LS10? Denny Ruigenstein

#memory #ELF

Current theory (may be nonsense ;-) - Display issues Problem: I can’t display specific values on the LED displays using the 1802 out command, as expected. * The original design the RC1802 used TIL311

#memory #ELF

Yes, swapped in a new chip. Voltage is 4.85v.

#memory #ELF

ca1naj610 wrote: Sure; a 74HC10 would work as well as the 74C10. I was just thinking of a vintage chip that would have been Elf-period correct, without having to rewire it for a 4023. Lee

#memory #ELF

P Todd Decker via groups.io wrote: I haven't looked at the RC1802 schematic closely. But the diode OR gates in the original PE Elf used 47k pull-down resistors. Since they all drove CMOS inputs, it wo

#memory #ELF

YES! Thanks all! I swapped out the 47K for a 3K3, and look what happened.. Not only did the strobe start working but the serial port burst into life! (If 300 baud can burst anything).

#memory #ELF

And I’m sorry for my CMOS / TTL sins.. :-(

#memory #ELF

In my case the wrong chip was stopping the strobe signal from being pulled low, so the display was not useful. Gates on the same chip also drove the TX/RX pins and so those didn’t work properly either

#memory #ELF

Should all the LS chips be replaced with HC? And, if so, can the originally specified 47K resistor values be maintained? --- P. Todd Decker 913-284-8814

#memory #ELF

David Schultz wrote: Ah! No CMOS loading problems there. Lee

#memory #ELF

An error in the previous post was brought to mi attention by another user. -Thanks again! This is the memory circuit in my system. It is added onto a Super Elf. View the drawing in MS Paint or Photo V

#memory

Hi John, Is the designer of that ELF available? Is there any ECO or Error fixes listed? I wish I had time to build the same project, but I've got too many projects piled on my bench and more on the sh

#memory #ELF

Oh, not getting this working is like an itch in my brain, and its making me careless. There is a pull up, and as far as I can tell the flip-flop reset is working fine. I did find one other clue though

#memory #ELF

John, you might just want to try comparing that circuit with the original ELF circuit and see if anything is missing/wrong.

#memory #ELF

Tor-Eirik—Thank you for contributing your design! I am glad we now know which member did these designs. It wasn’t obvious to me from your GitHub site. There are five of us now who have your boards and

#memory #ELF

Hi Tor-Eirik, I guess it's your design. There's no better way of testing a project than by having a group build! When you finish the corrections on the design, would you consider doing a board run for

#memory #ELF