Tindie

For RetroShield 6120 (PDP-8) for Arduino Mega/Teensy

Before this Teensy board, I used Arduino Mega 2560. With the Mega MCU running at 16 MHz, the highest clock rate I could achieve on my Z80 (using RetroShield Z80 from this store) was only around 0.5 to 0.6 MHz.

For better retro CPU performance, I needed a faster MCU. However, faster MCUs operate at 3.3 V, thus requiring logic-level converters. The whole thing (retro CPU or computer + logic-level converters + fast MCU) was becoming a bit unwieldy for a lazy guy like me.

This Teensy Adapter conveniently includes four logic-level converters, so if you are using Teensy 4.1 running at 600 MHz, you get both high performance and easy access to 5V CPUs.

Nicholas | March 15, 2024

Great kit for PDP-8/6120 Enthusiast

I love anything and everything to do with the PDP-8, including the 6120 processor. This kit and the teensy expansion kit were both easy to put together, and I was up and booted into OS8 in less than 15 minutes after I connected it to my PC. If you're interested in classic PDP-8 software, want something more than emulation but can't afford an actual PDP-8, and like soldering kits together yourself, I highly recommend this kit (and expansion board).

Mason | March 11, 2024

Appreciate the board.

I'm trying to learn computer engineering and science. This is really going to help me understand at a lower level about computer principles like how cpu's work.

Bought the pre-soldered for convivence since I don't trust myself with soldering, came in perfect condition.

Evgeny | Sept. 26, 2023

Great kit, works right away!

For RetroShield 8085 for Arduino Mega

For the assembled version, it's as easy as programming the Mega (2560) and plugging the shield in. The 8085 is already there plugged in. Just make sure that the serial speed is 115,200 baud. I look forward to the 8080 shield. :) Btw, soldering the two CPU headers could be handy (I would pay for it) to connect to a digital analyzer.

Evgeny | Sept. 26, 2023

Absolutely amazing shield

Seriously, it's just as easy as programming the Mega (2560) and plugging the shield in (for the assembled version). The Z80 is already plugged in. Just make sure that the serial speed is 115,200 baud. It has Microsoft BASIC! I look forward to the 8080 shield. :) Would really love the extra two headers around the Z80.

Davi | March 21, 2023

Very Happy with the Purchase

Simple and good kit to get started with 6502. Assembled the kit and tried k65c02_apple1.ino, things didn't worked. Didn't got the prompt (\) and no response to serial input. With some debugging and adding 5 microseconds delay after clock high and another 5 microseconds delay after clock low, things got working. Hooked up digital analyzer to understand the timing to figure out the difference. Overall good experience (debugging was the fun part).

Jay | May 14, 2021

Another fun kit

This kit was very quick and easy to build. It's been fun to run the 6502 from my Teensy. It's very quick to load new 6502 firmware into the teensy instead of pulling out an EPROM, burning it and replacing it as I've done many times in the past. Thanks!

Tim | May 11, 2021

Great fun and useful for reliving my Z80 days.

I've been a software engineer for over 30 years but stll hark back to my Z80 days in the early eighties. This works really well and doubles up as a Z80 chip checker for me. I would recommend this to anyone with a taste for retro-computing. I've ony used it with the Z80 RetroShield so far although I have the 6502, the 6803, 1802 and the 6809 boards also. Most of these are unfamiliar to me and I look forward to doing a bit of retro-exploration. Easy enough to use but not recommended for absolute beginners (need to be familiar with Arduino, handy with soldering and have some knowledge of 8-bit micros to get the best out of the kits.). Also handy as an interface board for the teensy as it gives you a bunch of 5V I/O pins which can be used for other purposes besides RetroSheild use.

Malcolm | May 11, 2021

Z80 and MBasic on an Arduino Mega!

Very high quality kit that worked immediately and allowed me to rediscover Microsoft Basic. Thoroughly recommend for anyone who has Z80 in their history!

Pierre | March 3, 2021

Full speed RetroShields

This board allows the old processors, 6809 for instance, to run a bit above 1MHz with a Teensy 3.6 where the Arduino Mega is ten times slower.

This speed allowed me to add many devices, emulated by the software, like a 7 segments display and a keyboard, and also an interface to the SD Card. They are seen as memory addresses by the RetroShield processor. The power of the Teensy 3.6 allows to stay above 1MHz most of the time.

I tried to adapt the software to the new Teensy 4.1, but its I/O registers are a bit different and force some modifications in the software. I must add that the software version for the Arduino Mega cannot run on the Teensy. You will have to take the right version, on https://gitlab.com/8bitforce/retroshield-teensy

The Teensy Adapter board is very easy to build. The PCB and components are of the best quality. All the documentation is perfect, and the schematics are not ugly at all, despite what the designer, Erturk Kocalar wrote :-)

I uploaded a small video on YouTube to demonstrate the Adapter and 6809 RetroShield : https://www.youtube.com/watch?v=1ehCcJTsoew

Pierre | March 3, 2021

Super nice way to run a 6809

When I was young I tried to build a simple computer based on a 6809, with very few circuits around, ram, rom and minimal address decoding. This was a failure because I had no tools to program the eeprom at home, and no enough experience.

This Retroshield is a very smart and easy way to make a 6809 run, at nearly the nominal speed with a Teensy 3.6. Ertuk Kocalar has designed a general bus to connect most of the old 8 bits processors: address, data and control lines are unified so that this only a question of software in the Arduino to emulate the ram, rom and devices around the processor. All the signals (E, R/W,...) are managed by the Arduino, so that the 6809 thinks it is in a real computer.

All the sources are available on GitHub and everything is documented, commented, and easy enough to understand... provided you know what is a processor. So you can use the software provided (simon6809: an advanced monitor), or develop your own. You simply have to assemble a program, transform it into a C array initializer (with xxd -i) so that it is visible as preinitialized ram or rom from the 6809. I added a 7 segments displays and keyboard card, and my own simple monitor, to resemble to the KIM-1 computer. This is what I wanted to do when I was young and it now works super nicely.

I slightly modified the connection between the Arduino and the Retroshield, by welding the connector above and making a male/female connector pcb. This allow to have both cards at the same level, instead of the Retroshield above the Arduino.

About the realization, all the PCB are top quality. Everything is included (pcb, processor, support, connector, led) and very well protected in the shipping. The 6809 is a 68B09E, the fastest and most advanced version of the 6809. I had no issue at all to make it run.

So I strongly recommend these boards if you want to learn machine and assembly languages. Those old processors are the most easy way to understand the concepts because they are simple: few registers, strong addressing modes, simple opcodes, all numbers are small and understandable compared to 32 or 64 bits of the modern processors.

I uploaded a small video on YouTube : https://www.youtube.com/watch?v=1ehCcJTsoew Sorry, I don't speak, because I am not good enough in English... (French native speaker).

Michel | Jan. 15, 2021

Very good product

Perform as advertised , (very well a matter of fact)) Easy to use. A++ product
i love this product and i recommend it

Paul | Dec. 25, 2020

Awesome board

For RetroShield 4004 for Arduino Mega

This is an amazing board allowing you to run and program the first ever microprocesssor. I've always wanted to build a board for the 4004 but it's difficult and not something you want to mess up. Using an arduino to emmulate hardware is a very cool idea. My board arrived promptly and worked out of the box once I'd got an arduino mega and 4004. Thanks again Erturk for an amazing board and opening up computing history to everyone.

Jay | Aug. 7, 2020

Speed up your retro processor!

This was a great kit and easy to build. It took no time to get it up and running. My 6809 board runs so much faster with it. I also have the Z80 board that I will try soon.

Jay | Aug. 7, 2020

I get to play with the 6809 again

My first computer was a Radio Shack Color Computer. It was amazing to run a dumb terminal off my computer when running OS-9. This kit was quick and easy to build and worked first time. I can't wait to play more with the 6809. With the Teensy adapter, maybe I can get OS-9 running again?

Jay | Aug. 7, 2020

Great Kit!

This kit was easy to build and I was able to get it working quickly. I highly recommend if you want to play with older microprocessors. Can't wait to spend more time playing with it. I have the Teensy 3.5 adapter board so it will be fun to run code even faster!

John | June 15, 2020

Want an Apple 1?

Fantastic idea - use an Arduino (or Teensy) to be the Ram, Rom, Clock and IO for a genuine 8-bit processor. This kit let me emulate an Apple 1 and play with the WOZMON and even BASIC. Nothing beats using hardware to run this retrocomputing stuff, and this is a easy way to get started. Bravo!

Rene | June 15, 2020

Great project, great support!

It took almost to months for the shields to get to me - half of the time spending at the custom's office. But now they arrived. Soldering was a matter of a few minutes. The printed schematics and hints are all you need. Software is available on the Internet. I will now start exploring it.
This is a great project if you want to explore different CPU types with minimal hardware effort. I developed several CPU cards to work in an Z80 compatible BUS system and know how complicate it can be to adapt the different signals, timings, (support chips for 8080) ... So these shields come really handy if you want to start with another processor almost at once and get to know it - before making your own project.

Thanks a lot! I'll be waiting for the other shields to come. 8008, 4004 etc. sound really interesting.

BTW: Also after sales support before shipping was great!

John | June 15, 2020

Speed up my 6502 Retroshield x 4 times!

I love the Retroshield projects - they are a great way to tinker with 8-bit CPUs and systems. Previously, I was using the Arduino MEGA to host them, but I have now switched to this Teensy kit: I'd never used a Teensy and this was a good excuse to investigate it. Assembly was easy - just the connectors, switches and an LED. Once I programmed it and connected the shield, the CPU ran way faster - I'm estimating about 0.8Mhz which means it's very close to the original Apple 1 speed. Very happy with it!

Alessandro | May 14, 2020

Amazing

Erturk is passionate about his products and wants his Customers to succeed!
I was very excited to find out that 8-bit-Force had already designed what I needed for a 6809-based project.
The design is solid, and the application examples are extremely useful to get me up and running quickly.
In addition to the Retroshield for 6809, I also purchased the Retroshields for 6502 and for the Z80.

Toshimichi | May 6, 2020

I tried assembling "Retro Shield 6502 for Arduino Mega".

I thought the idea of using only the original processor and emulating the others on the Arduino side to reproduce the computer of that time was interesting.
I purchased the "RetroShield 6502 for Arduino Mega", but assembling is as simple as soldering the IC socket, header and LED.
I wrote "k65c02_apple1.ino" to Arduino Mega to emulate Apple-1.
The APPLE-1 OPERATION MANUAL's TEST PROGRAM worked normally. Also, BASIC started, and a simple program also worked.

Ennio | March 17, 2020

Love it!

Love it! Works quit well. Only could use some updates to the documentation, like libraries required like DIO2.h, etc... Also bought the Z80!

Bryan | Feb. 4, 2020

Very happy

I bought the kit, the seller answered all my questions quickly and even went above any beyond to help me out. I've still got to put the kit together, but only like 4 parts. Got my mega all hooked up and ready to program. I definately recommend this seller! The parts are packaged very professionally too.

Tor | Nov. 26, 2019

Amazing daugtherboard.

I bought a bare PCB w/ surface mount parts soldered, shorted R2 and removed R4 as described in the assembly instructions , added a W65C02S and a LED. The result is an amazing daughterboard for Arduino Mega. Thank you for marrying the Arduino ports with the 6502 buses! A fantastic product if you are into Arduino Programming and retro Computing.

Jack | Nov. 14, 2019

Very pleased

I have not yet had a chance to actually use this, but wanted to drop a quick thanks to the seller here: The customer service, personal touch and build quality of this product are excellent. Cannot WAIT to tear into this thing! Bonus: It even came with a 6502 chip, which I didn't realize when I ordered it. I'll update this review once I've had a chance to use the shield in a couple weeks.

Tim | Nov. 4, 2019

Very good, lots of fun.

A great way to run Z80 code directly on a Z80 while simulating ROM/RAM & IO. Could be better documented as regards some of the tools you need to build projects (assembler etc.), would make it easier for complete newbies who've never experienced the Z80 . A good way to prototype before committing to building an actual board. As a Z80 developer from back in the day, I found it very nostalgic. I'm moving an old (simple but useful) monitor to the board and I'll release it when I've polished it up (and documented!).

James | Nov. 2, 2019

Very nice board, and I plan to do quite a bit with it.

We had a controller for a tape controller which ran on the 6809. I got several responses from Erturk to understand how to use this and look forward to doing a lot with it. Had no problems with Tindie, or 8bitforce.

Karl-Heinz | Oct. 10, 2019

All ok but a little bit to long delivery time

And i must pay 7 Euro here in sweden because of delivery from the United States ... that's not so nice

Massimiliano | Sept. 27, 2019

One of the best shield ever