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Joined: Wed May 15, 2019 1:17 am
Posts: 21
Hi all, Warren here. I grew up with Apple ][s and I've mainly done software and network admin in my life. Now I'm discovering the hardware side of things. I somehow managed to build my own 4-bit TTL CPU just by nutting things out myself (, and I'm still amazed that it works.

Along the way I've learned some Verilog, and now I'm discovering things like ROM latencies and propagation delays that I'd never considered before. Still so much to learn.

Wed May 15, 2019 1:37 am
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Joined: Fri Mar 22, 2019 8:03 am
Posts: 328
Location: Girona-Catalonia
Hi Warren,

Welcome to the forums. As you can see from a couple of posts before, I am very new to this forums too. I will be interested to know more and learn from your project, as my set of skills regarding hardware are absolutely basic. As a side note, I also attempt to make my own designed TTL CPU, but in my case it will be a very long journey because I have set a relatively large set of project goals, and I have some health issues that prevent me to work on it for as much as I would like. Anyway, delighted to have someone joining the forums with a particular interest in TTL chips!


Wed May 15, 2019 1:19 pm

Joined: Wed May 15, 2019 1:17 am
Posts: 21
joanlluch wrote:
I am very new to this forums too. I will be interested to know more and learn from your project, as my set of skills regarding hardware are absolutely basic. ... Anyway, delighted to have someone joining the forums with a particular interest in TTL chips!


Joan, if you are also new to hardware and want to build a TTL design, that's exactly where I was a couple of years ago. I'd highly recommend you look at my CSCv2 CPU (and video series).

There's only 12 chips, each one has a specific job and there is very little "glue" logic. The video series builds it step by step, and also explains the concepts behind each section of the build.

Cheers, Warren

Edit: also apologies Joan, I've just read the 7400 TTL CPU thread and I can see you are much more informed than I assumed!!

Thu May 16, 2019 12:47 am

Joined: Wed Oct 23, 2019 1:52 am
Posts: 7
Location: Sacramento, CA
commodorejohn checking in - I'm around on a variety of vintage-computing forums, particularly,, and the IRIX Network forums. Decided to check this place out when I ran across the link on, as I've had an interest in DIY CPU projects for some time. Still need to do a lot of brushing up on low-level electronics before I'd be ready to put anything together in hardware, but I've been scheming out a couple instruction set/architecture designs to suit my preferences for a while, and I've gotten to the point of starting to implement one in software...but more on that in a dedicated thread...!

"'Legacy code' often differs from its suggested alternative by actually working and scaling." - Bjarne Stroustrup

Wed Oct 23, 2019 2:50 am WWW

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1647

Wed Oct 23, 2019 8:38 am

Joined: Wed Nov 20, 2019 12:56 pm
Posts: 76
Nice to see a familiar name or two here from other forums!

I'm Alastair, I grew up first with a Commodore64 before moving onto an Amiga, so naturally I have soft-spot for 68K assembly language.

I've tinkered a fair bit with FPGAs over the last few years, learning enough of both Verilog and VHDL to hack on the Minimig FPGA Amiga replica project. I seem to be de-facto maintainer of the Turbo Chameleon 64 port of Minimig, and have ported cores to that platform and others, as well as tinkering with various FPGA-based SoC projects.

I forked the ZPU_small CPU a few years ago, and created a flexible variant of that, ZPUFlex, for use as a support CPU in retro-computing FPGA cores.

I'm now in the process of creating my own experimental CPU core from scratch, which I shall post about elsewhere in due course.

I stumbled across this forum a couple of days ago, having first found the OPC CPU series mentioned on Hackaday - my search for more information led me here. I'm especially interested in OPC5 because of its amazingly small logic footprint - it will fit as a supporting CPU where others won't.

Wed Nov 20, 2019 8:40 pm

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1647
Welcome! Nice to hear you find the OPC5 attractive, and that it attracted you here!

Thu Nov 21, 2019 9:27 am
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Joined: Mon Feb 03, 2020 4:08 am
Posts: 6
Location: Planet Earth, FL, USA
Finally joined here... been out on the forum for almost 7 years now.... have been involved with computers since the early 70's. Had a great career... 38 years with IBM, early transfer to Boca Raton in '84 to support the IBM PC Products and was part of IBM Software Group before it was called Software Group. Traveled the world for 25+ years working with large account customers, filled up 2 passports, was involved with lots of early technologies but still played with the 6502 during all of it as a hobby. Now retired after 45 years in the workforce and enjoying my hobbies, family and friends. It's a small world, as many same names out here as with the forum... who knew.

Regards, KM

Mon Feb 03, 2020 4:33 am
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Joined: Fri Mar 22, 2019 8:03 am
Posts: 328
Location: Girona-Catalonia
Welcome to the forum !!

Mon Feb 03, 2020 10:47 am

Joined: Mon Mar 08, 2021 6:36 am
Posts: 2
Hi Everyone,
Interesting small forum you have here; the talk of 6800's etc takes me back to my youth ...

I've been fascinated by electronics since my childhood and first worked with embedded in 1976 while a electronics technician as a busy electronics company. Back then I learnt all about building embedded gear while prototyping an iron ore flow gauge which used radioisotopes to measure the flow rate of ore falling off a vibrating feeder in Port Headland, Western Australia. The CPU was a National PACE 16 bit, 40 pin unit in a ceramic package and cost about $275 I was told.

Later I fell in love with the 6800 ISA on a HC11 and built projects using an old second hand SWTP development machine (I bought at a disposal auction for $25 AUD) with two 8" hard sectored floppy disks, a editor and assembler and eprom burner. That love still continues to this day, tho I have no desire to revisit the hardware.

After a couple of years using a Intel 8085 SDK and programming in machine code, the SWTP box seemed like I had died and gone to Heaven, even if it was plagued by horribly unreliable Molex connectors.

Add all the usual suspects, 6502, CDP1802, Z80, 6802, 6805, PIC, 8051, MSP430 etc and we arrive at the present where I use Forth on Cortex-M, mainly STM32F051 and maintain what is basically my blog as I progressed learning Forth starting around 2014.

I figured that as there was so little Forth online these days I might as well put my Mecrisp-Stellaris blog online, maybe the information may prove useful to others starting Forth. https://mecrisp-stellaris-folkdoc.sourc ... index.html

I also produce XSLT recipes for transforming SVD files to Forth Memory Maps and Bitfields, and Assembly equate files for Cortex-M (mostly STM chips), which automatically generates stuff like this:

$40021000 constant RCC \ Reset and clock control
RCC $0 + constant RCC_CR (  )  \ Clock control register
RCC $4 + constant RCC_CFGR (  )  \ Clock configuration register  RCC_CFGR
RCC $8 + constant RCC_CIR (  )  \ Clock interrupt register  RCC_CIR
RCC $C + constant RCC_APB2RSTR ( read-write )  \ APB2 peripheral reset register  RCC_APB2RSTR

and this

\ RCC_CR (multiple-access)  Reset:0x00000083
: RCC_CR_HSION ( -- x addr ) 0 bit RCC_CR ; \ RCC_CR_HSION, Internal High Speed clock  enable
: RCC_CR_HSIRDY? ( -- 1|0 ) 1 bit RCC_CR bit@ ; \ RCC_CR_HSIRDY, Internal High Speed clock ready  flag
: RCC_CR_HSITRIM ( %bbbbb -- x addr ) 3 lshift RCC_CR ; \ RCC_CR_HSITRIM, Internal High Speed clock  trimming
: RCC_CR_HSICAL ( %bbbbbbbb -- x addr ) 8 lshift RCC_CR ; \ RCC_CR_HSICAL, Internal High Speed clock  Calibration
: RCC_CR_HSEON ( -- x addr ) 16 bit RCC_CR ; \ RCC_CR_HSEON, External High Speed clock  enable

Nowadays I'm retired and spend my time making projects, gear and simple software. Everything I publish is either GPL'd or MIT depending on my obligations.

Mon Mar 08, 2021 8:01 am

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1647
Welcome, Terry, great to hear your story!

Mon Mar 08, 2021 8:12 am

Joined: Sat Feb 02, 2013 9:40 am
Posts: 1531
Location: Canada

Robert Finch

Mon Mar 08, 2021 4:15 pm WWW
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