Hack Chat Transcript, Part 1

A event log for Retrocomputing for the Masses Hack Chat

Spencer Owen and the RC2014

lutetiumLutetium 05/29/2019 at 20:010 Comments

OK, let's get started. I want to welcome Spencer Owen to the Hack Chat today to discuss his retro-clone of the ZX80, the RC2014. And anything else that comes up, of course.

Spencer, can you tell us a little about how you ended up in the retrocomputing world?

Kevin12:00 PM
I have built up two CPU boards for the 09 and one control board.

spencer12:00 PM
Hi! Yeah, I'm Spencer, and the RC2014 is my little Z80 based retro computer kit

spencer12:01 PM
For me, it started out as my own project to see if I could build a computer on a breadboard... and it kind of went off the rails from there :)

spencer12:01 PM

Noah Tompkins joined  the room.12:01 PM

Linker3000 joined  the room.12:01 PM

19-rsn-00712:02 PM
Ow yeah another project I am dying to pick up is my diy ZX80 but with more RAM :)

dannyvandenheuvel joined  the room.12:02 PM

Was that the first working version?

lawsong joined  the room.12:02 PM

spencer12:02 PM
When the Retro Challenge came around in 2014, I decided to enter the challenge by converting the breadboard computer to a PCB based computer

marblypup12:02 PM
Looks a bit like the Z8001 computer I built in the early '80s, Spencer. (Wasn't retro, then, though!)

19-rsn-00712:02 PM
good to see other people messing around with Z80 and 6500 series

spencer12:03 PM
Yes, that's the first working one. Technically, the top 3 breadboards were the first one, and the lower ones were expansions

spencer12:03 PM
@marblypup Got any photos of the Z8001?

Were you working from docs or did you reverse engineer it?

Bil Herd12:03 PM
Thats ambitious doing that on a breadboard.

Andrew Lindsay joined  the room.12:04 PM

spencer12:04 PM
There's a LOT of information out there via Google, although my board was hugely influenced by Grant Searles design.

Vinch joined  the room.12:04 PM

Kevin12:04 PM
I am always amazed to see people do complex builds like that on breadboard.

marblypup12:05 PM
@spencer Good question! I used to cross-assemble for it from an Amstrad PCW, which gives an idea of how long ago I last used it! Still have it, housed in a cigar box :-)

Linker300012:05 PM
Love to know the split between old'ns who were doing this stuff first time round and coming back (if they ever went away!) for the nostalgia, and those getting in to retro stuff for the first time. (I'm in the first category).

19-rsn-00712:05 PM
I love doing stuff on breadboard :)

spencer12:05 PM
My main limitation is software, so I made sure it was compatible with Grants design so that I could run his implementation of Microsoft BASIC on it.

Kevin12:05 PM
I do but usually smaller items.

Bil Herd12:06 PM
If we really had to prototype something in the old days we used wirewrap... now hard to get cheap ww sockets, connectors, etc.

marblypup12:06 PM
@Linker3000 I got into digital electronics when I was 14: 1980.

19-rsn-00712:06 PM
hehe wow I wasn't even born then

spencer12:06 PM
I need to try wirewrap one day. I've heard lots of good stuff about it, although in my mind, it still looks fragile and unreliable.

AlanH joined  the room.12:06 PM

Kevin12:06 PM
My 1802 CPU board I designed and built 39 years ago was built on real breadboard and is half point to point and half ww sockets.

19-rsn-00712:06 PM
born in 85. grew up with the C64 as my main loved system

Linker300012:07 PM
@Bil Herd: Can be done with regular sockets:

Andrew Lindsay12:07 PM
@Linker3000 I started with a Sinclair ZX80 when I was 13 in 1980

David Sean joined  the room.12:07 PM

Bil Herd12:07 PM
wirewrap has pretty well known impedances done right and there is no "loose" wires such as an inserted wire in a breadboard, many wraps around each post

spencer12:07 PM
I was born in 71, and grew up as a Sinclair fanboy (Sorry Bill!). It's that Sinclair link that I chose the Z80 to start with

19-rsn-00712:08 PM
hehe wow what are the odds of the 1802 getting mentioned! A friend of mine bought 3 boards with an 1802 on it and is playing around with one as we speak :)

Andrew Lindsay12:08 PM
Hi @spencer

spencer12:08 PM
@Andrew Lindsay Hey! How's your RC2014? :)

Kevin12:09 PM
I'm in the process of getting my 1802 board working again. It is, but there is at least one issue that I need to get to the bottom of for it to be back to 100%.

pi314159atgithub joined  the room.12:09 PM

marblypup12:09 PM
@19-rsn-007 The 1802 was a very early CMOS MPU, wasn't it? (Never had my hands on one.)

spencer12:09 PM
Actually, I've spotted quite a few names I recognise here as RC2014 customers, so I know that a lot of you already know about it. Is there anyone here that wants me to explain in a bit more detail what the RC2014 is?

Andrew Lindsay12:09 PM
@spencer Still working, I really should get the Forth ROM programmed so I can give that a try.

Kevin12:09 PM
@spencer I first saw your RC2014 system in an EEVblog video.

19-rsn-00712:09 PM
@marblypup :

Bil Herd12:10 PM
We looked at the COSMAC 1802 in the late 70's before there wasn'ta CMOS 6502, then we figured that our floating point routines would take a full second vs 150 ms

Peabody192912:10 PM
I would like to learn about your plans for the future of RC2014. Is 16 bits on the roadmap?

spencer12:10 PM
The EEVBlog video where Sagan builds the RC2014 Mini was awesome!

19-rsn-00712:10 PM
hey @Bil Herd ! Great to have you here man!

Bil Herd12:10 PM
What CAD do you favor?

Kevin12:10 PM
I know. Sagan did a great job for someone so young.

Linker300012:11 PM
Yes @spencer - 'tis your shout so go for it. (How's the cat!?)

spencer12:12 PM
@Peabody1929 I have looked at a 16 bit RC2014 (Using the 68000 processor), but despite a couple of prototypes, I've not got anything working yet. I think a couple of others are going down that route though, so there's likely to be someting 16 bit RC2014 compatible one day

Bil Herd12:12 PM

Andrew Lindsay12:13 PM
Would the backplane be a limitation on getting a true 16bit system going?

spencer12:13 PM
@Linker3000 Mo is quiet and subdued at the moment. I don't think she liked her trip to the vet today :-(

Bil Herd12:13 PM
More wires. :/

marblypup12:13 PM
@spencer I build a very, very simple MC68010 computer several years ago... mostly because it was the biggest DIP I could find :-)

spencer12:14 PM
The original Backplane 8 and Backplane 5 won't support 16 bit. But the Backplane Pro has 8 pins right next to the A0-A7 address lines which are unused. So that'll support 16 bit just lovely :)

19-rsn-00712:14 PM
I like salvaging (old) mcu's. recently salvaged a 8051 compatible mcu with 64k flash and 8k's of ram with a max speed of 30MHz

marten joined  the room.12:14 PM

Andrew Lindsay12:14 PM
Ah, the 8051. Used to do loads with them and their variants.

spencer12:15 PM
@marblypup The 68010 is a HUGE DIP chip. It takes soooo much force to insert or extract it. It's a beast to deal with :-)

Ed Thierbach12:16 PM
@spencer So, how did you go from hobby to side hustle to main gig? What did the decision process look like for you?

epooch12:16 PM
Do you have supply chain issues using so many discontinued ICs?

Bil Herd12:16 PM
Give me 32 8051's and I can move the world, or at least build one bitchin vending machine controller

19-rsn-00712:16 PM

Bil Herd12:16 PM
We used to call the DIP 68010 the Hershey Bar

marblypup12:17 PM
@Bil Herd LOL

spencer12:17 PM
. @Bil Herd Just spotted your "What CAD" question. I'm a KiCad guy. Tried Eagle many years ago and never got on with it. The RC2014 was my 2nd ever PCB design, and KiCad just worked out well for me for that.

AlanH12:17 PM
Don't eat it Bill

AlanH12:17 PM

Remember those pin compressors for big DIPs? Those were handy

Lex Landa12:18 PM
@spencer Hi. I'm just getting into PCB design, and I chose KiCad too.

spencer12:18 PM
@epooch No, not really. Pretty much everything I use (or at least, the stuff that I sell) is still being manufactured. Even the Z80 chips are now coming out with a 2019 datecode on them

19-rsn-00712:18 PM
build a machine that puts holes in walls @Bil Herd ;)

19-rsn-00712:18 PM
great funny story :)

Linker300012:19 PM
I buy new from the mainstream UK distys (Farnell and RS) - often cheaper that the 'bay, where the sellers stick 'retro' in the description and bump the price.

Bil Herd12:19 PM
Heh I just saw the Caddyshack clip where Bill Murray eats the chocolate bar

Marten Feldtmann12:19 PM
I think its still amazing to see, that most of the Z80 chips are still produced, but the 68K family is more or less gone !?

Bil Herd12:19 PM
Z80s were in lots of controllers.

spencer12:20 PM
The very first iteration of the RC2014 was all made with salvaged parts. Thanks to a donation to Nottingham Hackspace, we had loads of old logic and memory chips to work with.

Gregory Nutt joined  the room.12:20 PM

19-rsn-00712:20 PM
I see them everyday...Z80's work at a company where industrial stuff is repaired

marblypup12:20 PM
@marten I got my 68010 from They have lots of old stuff, but probably not still being made. (Motorola begat Freescale which is now part of NXP.)

Bil Herd12:20 PM
@19-rsn-007 Yeah I have to explain that to my son some day and tell him not to do that.

19-rsn-00712:20 PM
a lot of z80, 8031, 8051, 8085, 68k

Kevin12:20 PM
@marblypup There was the Dragonball microcontrollers for a while. They had a 68k core.

Marten Feldtmann12:20 PM
Yes, but they are older that the Z80 and the 68K is also very well used the 80-95 and its still difficult 020 or 030 chips, the later is even more difficult to get

Gregory Nutt12:21 PM
For 16-bit 65xx/68xx an option might be: I am fond of the ez80 for almost retro too.

spencer12:21 PM
@19-rsn-007 I'd love to know what kind of industrial stuff is still out there with Z80s in it. And is there still new industrial stuff being designed for Z80?

Bil Herd12:21 PM
@spencer So are you moving on PCB currently?

Bil Herd12:21 PM

19-rsn-00712:21 PM
what about the Z8 ? I know I have one around here somewhere. a romless version

Kevin12:22 PM
The Z-80 is one of my two favourite 8-bit CPUs.

AlanH12:22 PM
started to design a ezDuino/80 with a ez80... you haven't done robotics right until you've done robotics with CP/M

marblypup12:22 PM
@spencer Is this a good point to ask if you have any plans for a Z280 CPU board? I was thinking 8-bit Z80-bus mode, but it also has a 16-bit 'Z-BUS' mode (like the Z8000s).

Bil Herd12:22 PM
@kevin Whats your other (please say 6502)

spencer12:22 PM
@Bil Herd Yeah, that breadboard photo I posted earlier was from 4 years ago. The RC2014 looks more like this now

Marten Feldtmann12:23 PM
Z280 board is already available

AlanH12:23 PM
I work in the modern toy industry and the 6502 is alive and well in lots of dice/cob chinese toy ICs

David Richards joined  the room.12:23 PM

marblypup12:23 PM
@marten Wahoo!

Bil Herd12:23 PM
@spence NICE. Love the form factor@

Bil Herd12:23 PM

Kevin12:23 PM
@Bil Herd I haven't really ranked them but it would probably be 6809, Z-80, then 6502. I loved what you could with the Apple ][ computers.

marblypup12:24 PM
@kevin I build a 68HC11 computer in 2006. That's essentially a 6809 MCU.

Gregory Nutt12:24 PM
Western Digital (the original 6502 designer) continues to develop and extend 6502 based parts

Marten Feldtmann12:24 PM

spencer12:24 PM
For those that don't know, the RC2014 is a very simple modular computer on a passive backplane. So that means that each individual module is very very simple, but also that individual parts are easily upgradeable. eg some people have already made a Z180 and Z280 CPU module for it.

epooch12:24 PM
How has Tindie worked out as a sales platform?

Bil Herd12:24 PM
Yeah I like the 6809 and the 6845 and 6847 will always be dear to my heart as well (graphics)