Ninjabyte ZPX-128 (universal Z80 computer kit)

u/novenary January 30, 2016, 10:03:24 AM

I think you shouldn't avoid smd at all costs, chips with a big pin spacing are easy to solder to a PCB without any particular equipment. I soldered a chip with 0.6mm spacing with a very cty iron (cheap non regulated thingy, about 10 to 20 dollars) and that was my first smd job. For those interested, search YouTube for tutorials, especially the EEVblog one.

Edit: here it is.

He does show some mid-range equipment in the video but I can assure you that for most things, a $20 iron is enough. You definitely want a good iron if you're doing that stuff more often though.

Last Edit: January 30, 2016, 12:17:26 PM by Streetwalrus

u/DarkestEx February 07, 2016, 01:24:08 AM

Great news! All the remaining parts arrived today (except for the Z80 but I haven't ordered it yet and I will wait with that as long as possible as it is horribly expensive).
I do have a 6 MHz Z80 laying around and if it is CMOS then it'll work just fine.
Breadboarding will start soon. I am sick atm, so this will have to wait till Monday I guess.

u/Dream of Omnimaga February 07, 2016, 01:55:18 AM

Good to hear.

u/DarkestEx February 07, 2016, 09:19:48 PM

Quote from: Streetwalrus on January 30, 2016, 10:03:24 AM
I think you shouldn't avoid smd at all costs, chips with a big pin spacing are easy to solder to a PCB without any particular equipment. I soldered a chip with 0.6mm spacing with a very s***ty iron (cheap non regulated thingy, about 10 to 20 dollars) and that was my first smd job. For those interested, search YouTube for tutorials, especially the EEVblog one.

Edit: here it is.

He does show some mid-range equipment in the video but I can assure you that for most things, a $20 iron is enough. You definitely want a good iron if you're doing that stuff more often though.

The Microcat's chip had a spacing of .5 mm (center of one leg to the center of the next one). I don't want this to get another SMD failure, so I will stick with DIP components for all costs. Also this is a kit, so the user will solder it, not we.

u/utz February 09, 2016, 11:37:32 PM

Quote from: DarkestEx on February 07, 2016, 01:24:08 AM
Great news! All the remaining parts arrived today (except for the Z80 but I haven't ordered it yet and I will wait with that as long as possible as it is horribly expensive).

What? A brand-new Z80 costs like 6 EUR max. Zilog even used to give them away for free to developers. If you write them a nice mail explaining what your plans are, they might still do that.

u/DarkestEx February 09, 2016, 11:43:01 PM

Quote from: utz on February 09, 2016, 11:37:32 PM
Quote from: DarkestEx on February 07, 2016, 01:24:08 AM
Great news! All the remaining parts arrived today (except for the Z80 but I haven't ordered it yet and I will wait with that as long as possible as it is horribly expensive).

What? A brand-new Z80 costs like 6 EUR max. Zilog even used to give them away for free to developers. If you write them a nice mail explaining what your plans are, they might still do that.

I am not talking about the chip. The shipping from Leeds (UK) is the problem. As I would order only the single Z80, I would have to pay 10€ in shipping as my total sum stays under 30€.
The chip will be bought from Farnell (element14) via hbe.

u/utz February 09, 2016, 11:59:02 PM

Why don't you just buy it from Reichelt or something?

u/DarkestEx February 10, 2016, 12:14:38 AM

Quote from: utz on February 09, 2016, 11:59:02 PM
Why don't you just buy it from Reichelt or something?

Because they dont sell it.........

u/utz February 10, 2016, 12:24:48 AM

Sure they do.
https://www.reichelt.de/ZILOG-Controller/Z84C00-06MHZ/3/index.html?ACTION=3&GROUPID=2951&ARTICLE=23029&OFFSET=16&SID=15VXUYn6wQATcAAJDxs745604d32328fc18e01feb2ea7ee771ef1&LANGUAGE=EN

u/DarkestEx February 10, 2016, 12:26:20 AM

Quote from: utz on February 10, 2016, 12:24:48 AM
Sure they do.
https://www.reichelt.de/ZILOG-Controller/Z84C00-06MHZ/3/index.html?ACTION=3&GROUPID=2951&ARTICLE=23029&OFFSET=16&SID=15VXUYn6wQATcAAJDxs745604d32328fc18e01feb2ea7ee771ef1&LANGUAGE=EN

Thanks for trying, BUT:

Quote from: DarkestEx on February 07, 2016, 01:24:08 AM
I do have a 6 MHz Z80 laying around and if it is CMOS then it'll work just fine.

I have exactly that one laying around as I bought it one year ago. For the ZPX-128 I need a 10 MHz CMOS one.

u/utz February 10, 2016, 12:39:41 AM

Ah, I see. Unless I've overlooked something, you didn't mention before that you want a 10MHz one. In the first post, you say you want to use 6/8 MHz.

u/DarkestEx February 10, 2016, 01:25:40 AM

Quote from: utz on February 10, 2016, 12:39:41 AM
Ah, I see. Unless I've overlooked something, you didn't mention before that you want a 10MHz one. In the first post, you say you want to use 6/8 MHz.

Oh I hadn't fixed it in the main post yet. Sorry.
I just corrected it there.

So, the ZPX-128 will have 16 KB kernel space that is write protected. The kernel is in RAM, but the first 16 KB can only be written to by the PXA. All programs that will run on the ZPX-128 shall always return cleanly and shall never require a restart. Having the kernel protected is a another safety so that it doesn't accidentally corrupt. This is important as the whole computer must shutdown before powered off. Also I don't like having to reset everything after running a single program.

u/SiphonicSugar February 11, 2016, 02:07:56 AM

I think that this just inspired me to make my own little mini computer... Like the one that I posted about that would be my dream calculator...

u/Dudeman313 February 11, 2016, 03:13:42 AM

I couldn't do that if I tried.

u/DarkestEx February 28, 2016, 10:21:50 PM

So, we'll add headers on the board to break out the PS2 so that people can easily integrate it into e.g. some keyboard based unit.
Also I plan supporting multiple keyboard layouts. What special language characters do we need? I plan to add äöüÄÖÜßàáâÀÁÂèéêÈÉÊôÔîÎ
Are there any others that you want me to add aswel?
There will be no Unicode support but there will be some characters from the extended ASCII set.
The unit will be flashed using a serial interface on the back. There will be a RS232 type DIN connector that will have 2 GPIO, RESET, SDA, SCL, RXD, TXD, VCC and GND on it.
You can use it to program and update the unit. I plan to add a free space to eventually allow for adding a USB serial device to allow for easier flashing. This port is only important for interfacing with the PXA and updating it. For updating the Z80 ROM you just need to change the kernel file from the SD card. It will be copied to the write protected first 16 KB of RAM at boot.