RC2014 8bit kit computer?

balloon

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May 20, 2019
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balloon.im
I learned RC2014 for the first time. But I can introduce you to other Z80 boards:
  • Z80-MBC2
  • KZ80_IOB (Japanese description)
 
May 22, 2019
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I've been looking longingly at the RC2014. I've got emulators running CP/M (RunCPM, two Altairduinos, and an Altair Clone), but I'd love to have a real Z80 computer running on native hardware.
 
May 22, 2019
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There's also a guy on EBay selling a Z80MB64, which is an RC2014 compatible motherboard with the CPU and memory directly on the board, rather than a daughter card. And it runs at 20 MHz.

It's a super simple build; I've thought about grabbing a copy of the PCB artwork for the Z80MB64 and building my own. I'd really like two, so I may buy one of his to use as a template, then build a second one.
 

Tuireann

New Member
May 31, 2019
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Columbus, Ohio
That does look pretty cool especially with the RC2014 expansion slots. I'll have to look into this more over the weekend. Thank you for the info!
 
May 22, 2019
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If you think you want to have a PCB fabbed, let me know. I believe most places have a minimum order, and we could get together and split the price. I haven't actually had a PCB made before, so I'm kind of learning as I go here, though. =)
 

Tuireann

New Member
May 31, 2019
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Columbus, Ohio
I was actually looking to see how hard it would be to print something for prototyping on my current 3d printer with conductive filament. With a single extruder apparently its pretty hard. I have had some PCB prototyped before. Sparkfun used to do a monthly onesy-twosy batch of various proto boards for customers but that was years ago so that might be something worth looking into.
 
May 22, 2019
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Ok. I'm not ready right now, but we could source all the parts and see if it's all available... I wouldn't want to fab PCBs, only to find out that a vital component isn't available. =)


For example, the last time I went to look at Z80s, the 20MHz chip was out of stock. (I actually have an 8MHz chip I bought to fix my Spectrum 128.)
 

Tuireann

New Member
May 31, 2019
13
5
3
Columbus, Ohio
Yeah, makes sense, I need check all the P's and Q's on it anyways. Helping a friend move to Ohio from St Louis tonight so will likely be looking into it tomorrow.
 

Tuireann

New Member
May 31, 2019
13
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Columbus, Ohio
So after looking into it, the Z80MB64 seems like a versatile solution. That it requires a computer to boot is annoying but, obviously, you could include anything with an expansion card. Mouser currently has the Z84C0020PEG in stock it requires but I'm still trying to source the rest of the BOM. The Altera chip I am unsure about because searching the PN gives me a lot of suffixes and I'm not sure which, if any, is the correct chip yet.

I was also looking into PCB fab and firstPCB will do 2 layer PCB 102mm^2 qty 5 for an estimated $20.24. PCBWay has generally good reviews and will do the same for an estimated $27. Both excluding shipping etc.

Also, my new hat arrived today. :)
rsz_z80.png
 
May 22, 2019
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That it requires a computer to boot
It requires a computer to boot? I must have missed that part.

I thought this was a stand-alone Z80 computer, and you just needed some sort of serial terminal to access it. (I was planning on using a Pi with custom terminal software.)

** Okay, I see the issue. The computer doesn't use a ROM, but loads the ROM files into battery backed RAM. So the first time you boot the board, or if you pull the battery, you have to use a PC to load the firmware.

Yeah, i don't like that. I'd rather have something with a proper ROM. And using an FPGA for the system controller.... I guess I'm back to lusting after the RC2014.
 
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Tuireann

New Member
May 31, 2019
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Columbus, Ohio
I wonder if it would be possible to replace the SRAM with an FRAM chip. That would solve the permanency of loaded programs since FRAM is non-volatile.
 

Tuireann

New Member
May 31, 2019
13
5
3
Columbus, Ohio
Looking around it appears almost every board out there uses UART to bootstrap. I found a Z280 board that didn't but still haven't found anything with a Z80 that doesn't require an expansion card to accomplish that. I would have thought this would be pretty standard.
 
May 22, 2019
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Looking around it appears almost every board out there uses UART to bootstrap. I found a Z280 board that didn't but still haven't found anything with a Z80 that doesn't require an expansion card to accomplish that. I would have thought this would be pretty standard.
Have you looked at the Z80 Membership Card? I believe that uses a 32K EPROM and a 32K RAM chip. No boostrap there - although it also doesn't run CP/M.

Although the more I think about it (and partially due to a comment on the Altairduino mailing list), I'm wondering how well an RC2014 backplane would interact with something like a Teensy running an instance of RunCPM.