My project with eZ80

[KnivD]

Hi All,

I am new here, just joined the group to share the news about my new OSH project - the Z20X computer.

Here is the link with more information: https://z20x.computer

Looking forward to your comments

Thank you

[Interocitor Steve]

Welcome to the group KD!

Very nice, simple design. So much capability. Love the display. 

Most impressed with the web site with all the details. =Steve.

[Karl Albert Brokstad]

Welcome Konstantin

You arrived at the right place.

Very nice design, what about the system software?

Have you considered offering the kit for sale?

Karl

[KnivD]

There is no software for it yet. I only know that the hardware works :)

Working to prepare full DIY kits for release in March. Currently have a couple of prototype PCB from the first version that I won't need anymore since the final release for the kits is already in the factory. I am happy to let them go for free to interested people, especially if there could be any help with getting the initial software running. Currently working on some more related hardware too.

[Bill Shen]

I am in USA, I like to have a pc board. I think CPM can easily ported to eZ80. The 512K RAM is big enough for CPM files and small RAM disk. Please let me know if you still have board available. Thanks,
Bill

[Richard Deane]

If anyone is porting cp/m to this then it might be worth a look at Hackaday CPM50MK2 project where the cp/m implementation for jessiexm's ez80 design looks cool. Licensing will probably permit that to be used.

Richard

[KnivD]

Hi Bill, yes I still have a couple of r0 PCBs. Please contact me at knivd at me com

[G Kr]

Hello everyone, I'm currently struggling with the cpm50mk project. Does anyone have an idea how the resistor and capacitor on the RESET pin (have only come onto the board later) should be dimensioned?

Gerd

[Bill McMullen]

After a quick look at the CPM50MK2 schematic, it appears to me that there's simply a 10K pullup on the reset line.  That works on an eZ80F91 where reset is bidirectional (Schmitt & open drain) and I actually used 4.7K on the Min-eZ for faster response.  On the eZ80F92/F93 & L92, reset is simply an input with a Schmitt trigger and I've successfully used a 100K pullup and a .022u cap to ground on my eZ-Tiny with an F92 or F93.

[G Kr]

Hi Bill, since the author probably didn't change the 10k pullup, a 100n capacitor against ground comes close to your example. What I can't explain is the additional resistance to ground, which would have to be large in order not to reduce the potential at RESET. But what is it good for? You can see the additional installation on the pictures in the gallery of the project between the RESET switch and the USB connector. https://hackaday.io/project/161496/gallery#448687ed74e92d5a168f53386ffd3d49

Gerd

[Bill McMullen]

Gerd: Per the hackaday logs, "The first revision required a blue wire to correct an issue with reset and the addition of a resistor and capacitor".  The picture isn't very clear but I assume that is the blue wire in the picture but it would appear that the hackaday schematic and Eagle files are prior to Revision A.  The original designer may be able to give you a better description of the modification(s).

[G Kr]

Hi Bill,
unfortunately the designer (Jesse Marroquin) seems to have abandoned the project. I tried to reach him via email... but if the address is still up to date. In any case, he cannot be reached via the project. Github also doesn't allow messages. I'm not familiar with that either. The change with the cable is a missing connection to the RESET on the Z8. However, I can't imagine why a resistor parallel to the capacitor at the RESET should be good. Unfortunately, my efforts to provide the Z8 with the firmware have not been successful so far. Of course, things could have gone wrong during assembly. Almost looks like a total loss. I thank you for your contribution.