Z80 Computer - Part 3 Output

[@jamesross3939]

Very well done. I watched a few of these a while back but i started over and want to watch the entire series.

[@miketrissel5494]

Don't know if there has been a big change since the late 70's, but with a common cathode display, and a decoder driver feeding it, we used to put a limiting resistor in the cathode line, rather than a separate resistor in each segment line. The display dims just a tad between 1 lit segment, and all of them, but with your more modern constant current driver chip, I think it will work quite well. The guy has been dead for years, but if you can find a Forrest Mimms logic cookbook, you may enjoy it - keep up the good work. Most newer ones have no one teaching this anymore. Mike

[@SteveRaynerMakes]

I don't think adding a resistor will help because the driver will just increase the voltage to maintain the constant current. I'm wondering if I can pulse width modulate the ripple blanking line to dim the display a bit, but not sure. I'm beginning to think it was a mistake to use these chips, but hey, i've done it now. I had a look for that book, but couldn't find it.

[@vvtor]

Excellent videos, I really enjoy your explanations.

[@SteveRaynerMakes]

Thank you. Hopefully more to come once I get back into things.

[@edabean007]

Great content thank you 😀 i am trying to make a similar z80 breadboard pc. i used 2 old mc14495p1 chips i had in my draws to do the data bus decoding for 7 segment display. subbed and looking forward to more great content!

[@SteveRaynerMakes]

Hi, and thanks for sub. Yes the MC14495P is another excellent choice. I wasn't aware of that chip.

[@PE4Doers]

Steve, I added a 'Like'' here 🙂

[@user-vq5rx5ym6b]

Legal!! 😃 Eu quero montar um z80 pra mim também!!

[@byteforever7829]

This is absolutely brilliant!

[@JarppaGuru]

6:35 nope g is middle led. there is no dp signal on that chip

[@SteveRaynerMakes]

yes I made a mistake there

[@JarppaGuru]

14:51 cut wire quickly

[@SteveRaynerMakes]

ha ha, yes, but red or blue?

[@ricardokaraatanasov1705]

I'm making that computer too🤭

[@SteveRaynerMakes]

have you made more progress than me?

[@donnybigboy]

I love your videos Steve, so informative and you explain things in a way I can understand. One question though, you said you would use a different chip rather than the DM9368n as it used a lot of current, Can I ask which chip would you use? I assume your 7 seg display is a common cathode type?. Thank you

[@SteveRaynerMakes]

Honestly, I'm not sure. It's difficult to find anything that will do hex digits. I quite like the DM9368N chips but they do consume a lot of power. There is a note in the datasheet saying that the RBO terminal can be or-tied with a modulating signal to provide pulse modulating intensity. I'm wondering if that would reduce the power by dimming the outputs. bean did mention below, the MC14495p1 chip as an alternative. The MC14495P1 has 290ohm resistors built-in (as opposed to the DM9368N constant current solution). Meaning you could add additional resistors in series to reduce the current further. The reason I want to avoid resistors is that I would need 7 for each digit, meaning 42 resistors in total.

[@donnybigboy]

@@SteveRaynerMakes Hi Steve, thank you for that. I have also looked at the MC14495p1 and the CD74HCT4511E. Sadly I only had a common anode 7 seg so could not really try it. Thank you to you and everyone elses comments as I learn a lot from you all.

[@youcefassou1592]

Hi steve Iam using dm9368n like you but i can see only numeric and tried but it count only from 0 to 9 and 10 to 15 blank no abcdef. And when i conect the LE to ground the displays is only 8 forever any idea what iam doing wrong as you plugged it on ioreq on z80. Can it work just with toggles switches.

[@SteveRaynerMakes]

you could try looking at the truth table on page 2 of the datasheet, and check that inputs A0 to A3 are as expected.

[@alfredomeurerjunior9547]

Mr Steve, could you please to show the program that you used for this nice one board Z80 computer? Will be very good we have it, if you have more programs for this kit, please show them. Thank you so much for your kind help.

[@JarppaGuru]

22:06 hookup reset to iorq line with diode so it reset same time and reading 0 but z80 not reset when iorq bcoz diode xD