Motorola 68000 SBC Runs Again with a Raspberry Pi on top

-
MC68k SBC with a monitor, keyboard and mouse

Single-board computers have been around a long time: today you might be using a Raspberry Pi, an Arduino, or an ESP32, but three decades ago you might find yourself programming a KIM-1, an Intel SDK-85, or a Motorola 68000 Educational Computer Board. These kind of boards were usually made by processor manufacturers to show off their latest chips and to train engineers who might use these chips in their designs.

[podstawek] found himself trying to operate one of these Motorola ECBs from 1981. This board contains a 68000 CPU (as used in several Macintoshes and Amigas), 32 kB of RAM, and a ROM program called TUTOR. Lacking any keyboard or monitor connections, the only way to communicate with this system is a pair of serial ports. [podstawek] decided to make the board more accessible by adding a Raspberry Pi extended with an RS232 Hat. This add-on board comes with two serial ports supporting the +/- 12 V signal levels used in older equipment.

It took several hours of experimenting, debugging, and reading the extensive ECB documentation to set up a reliable connection; as it turns out, the serial ports can operate in different modes depending on the state of the handshake lines. When the Pi’s serial ports were finally set up in the right mode, the old computer started to respond to commands entered in the terminal window. The audio interface, meant for recording programs on tape, proved more difficult to operate reliably, possibly due to deteriorating capacitors. This was not a great issue, because the ECB’s second serial port could also be used to save and load programs directly into its memory.

With the serial connections working, [podstawek] then turned to the aesthetics of his setup and decided to make a simple case out of laser-cut acrylic and metal spacers. Custom ribbon cables for the serial ports and an ATX break-out board for power connections completed the project, and the 40-year-old educational computer is now ready to educate its new owner on all the finer points of 68000 programming. In the video (embedded after the break) he shows the whole process of getting the ECB up and running.

[podstawek] made a similarly clever setup with a Commodore 64 and an Arduino earlier. [Jeff Tranter] recreated a similar 68000 development board from scratch. And a few years ago we even featured our own custom-built 68k computer.



from Blog – Hackaday https://ift.tt/2V5p0N0

Comments

Post a Comment

Popular posts from this blog

Modern Radio Receiver Architecture: From Regenerative to Direct Conversion

-
Image
Modern radio receivers have a distinct advantage over the common early designs which I covered in my previous article . Most of the receivers you will have worked with over the past couple decades are designs by Edwin Armstrong ; regenerative, superregenerative, or most commonly superheterodyne. These are distinguished by a few fascinating key traits that bring both benefits and drawbacks. Today let’s dive into Mr. Armstrong’s receivers. I’ll also talk about DC receivers which, despite the name, are not made to listen to batteries. These are receivers you are much more likely to encounter in modern equipment. Regenerative and Superregenerative The regenerative receiver is all about doing more with less. You still see some of these in simple applications like RF remote controls. The idea derives from how an oscillator works. In a simple way of thinking, an oscillator is an amplifier with enough positive feedback that any tiny signal at the right frequency will amplify and then, throu...
Get this one»

Hackaday Links: May 31, 2020

-
We begin with sad news indeed as we mark the passing of Marcel van Kervinck on Monday. The name might not ring a bell, but his project, the Gigatron TTL computer , certainly will. We did a deep dive on the microprocessor-less computer a while back, and Marcel was a regular at conferences and on the Gigatron forums, supporting users and extending what the computer can do. He was pretty candid about his health issues, and I’ll add that when I approached him a few weeks ago out of the blue about perhaps doing a Hack Chat about Gigatron, he was brutally honest about how little time he had left and that he wouldn’t make it that long. I was blown away by the grace and courage he displayed. His co-conspirator Walter Belger will carry on the Gigatron mission, including joining us for a Hack Chat on June 24. In the meantime, this might be a great time to pick up a Gigatron kit before they’re all sold out and get busy soldering all those delicious through-hole TTL chips. May of 2020 is the mo...
Get this one»

Homebrew 68K Micro-ATX Computer Runs Its Own OS

-
Image
We’re no stranger to home built Motorola 68000 computers here at Hackaday, but more often than not, they tend to be an experiment in retro minimalism. The venerable processor is usually joined by only a handful of components, and there’s an excellent chance they’ll have taken up residence on a piece of perfboard. Then [NotArtyom] sent in his Blitz , and launched the bar into the stratosphere. Make no mistake, the Blitz isn’t just some simple demo of classic chips. The open hardware motherboard has onboard floppy, IDE, and PS/2 interfaces, with a trio of 8-bit ISA expansion slots for good measure. The  Motorola 68030 CPU is humming along at 50 MHz, with 4 MB of RAM and 512 KB of ROM along for the ride. Designed to fit the Micro-ATX motherboard standard, you can even mount the Blitz in a contemporary PC case and run it on a standard ATX power supply. An earlier prototype of the Blitz motherboard. As if the hardware wasn’t impressive enough, [NotArtyom] went ahead and created hi...
Get this one»