Z80 Retrocomputing 17 - Enhanced CPU Board

[@TomStorey96]

HALT is an output so doesn't need to be pulled up. INT, NMI, BUSRQ, WAIT and RESET are the 5 control inputs that should be pulled up for wire OR, or use appropriate active low logic to feed in to them.

[@Titan_Logic]

Excellent work, I think a revision for a slight LED delay is a good idea.

[@nilswegner2881]

Are you planning on building a video board for your RC2014? That would be really cool!

[@wesleymays1931]

For console-like video, try the TMS9918 video chip add an OR gate, some decoders, latches, and a RAM chip and BOOM! you have a video board

[@GeeWillikersMan]

Shouldn't that solder bridge be on the MAX811 reset line to disable it, not in its current position?

[@wesleymays1931]

The bridge (SJ1) is to be soldered across when you can't solder the MAX811, to let the reset button work without having to solder that tiny little chip. It goes across the input and output of the chip, which means if you soldered it it would jump across the chip, and it's currently open.

[@_rob6588]

You should diffuse your LED's to make them easier to view.

[@georgysb]

What's the sense to pull up HALT pin while it's OUTPUT and so it just can't float? BTW in Z80 datasheet only BUSRECK and INT pins are mentioned as being needed to be pulled up.

[@pcuser80]

I see in the assembler listing: RXA: waitForChar: LD A,(serBufUsed) CP $00 JR Z, waitForChar Controlling like a madman if a key has been pressed. (interrupt driven) This is better and saves power too. RXA: waitForChar: HALT LD A,(serBufUsed) PUSH HL LD HL,(serRdPtr) INC HL Better?

[@CARLOSINTERSIOASOCIA]

Is it possible to program an arduino with it?

[@semibiotic]

Do you find RC2014 base contruction (single row 0.1'' header connections) handy and reliable enough ? For me, child boards should be bent all the time.

[@smbakeryt]

Given that the boards are relatively small, I think it's fine, and it keeps the complexity and cost down.

[@semibiotic]

@@smbakeryt I see, thank you. In my assembly I use "arduino shields" form-factor, yet, partially, because I use Arduino Mega as debug, system and, currently, even UART controller (as Z80-SBC2 does).

[@jetraid]

Maybe a vumeter with a capacitor for each line, when the line have more activity the vumeter goes up. less activity the capacitor discharges and go low.

[@smbakeryt]

Don't give me any crazy ideas... I do have a pile of IN-13 Nixie Tube bar graph tubes waiting to serve some purpose.

[@jetraid]

Jaja, I only say led bars, not nixie.

[@101blog]

The Magic Eye tubes would be the coolest for this purpose

[@KalterKrieger]

Are the boards available in Europe, too?

[@yorgle]

I've got a big cap on my reset line which seems to work well with doing the power-on reset... what does using the Max811 offer that the cap method doesn't?

[@smbakeryt]

The max811 offers a few advantages, for example it will detect brownouts, should be tolerant of slow power supply rise, and guarantees a single 140ms reset pulse. When I wrote up the power-on reset blog post, I tried both the max811 and a resistor/cap + schmitt trigger reset circuit. In one of my projects I had an issue where the resistor/cap circuit wasn't working for me, so I settled on the max811.

[@inerlogic]

Oo.... amber flashes with each keypress....

[@edatki]

7:23 Voice crack

[@davebulluk]

didn't exactly affect anything though, did it.

[@trombb8782]

bla bla bla, loosing time