z80

114 Articles

Strange English Teaching Computer Might Have Been Big In Japan

October 21, 2024 by 9 Comments

[Ctrl-Alt-Rees] bought something strange on an auction site: a Japanese Cefucom-21 from 1983. No? Didn’t ring a bell for us either. The legend on the front boldly proclaims: “CCI Multipurpose SLAP Computer,” so maybe it is some kind of computer, but it is definitely strange. For one thing, the “screen” isn’t a screen at all. [Rees] has found that it has something to do with teaching English. You can see the odd beast in the video below.

We don’t know how common these were in Japan, but they appear to be virtually unknown everywhere else. Inside is a Z80 computer based on a  Sanyo PHC-25, which is a little better known.

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DIY Core Rope Memory Z80 Demonstrator Generating A Fibonacci Sequence

October 16, 2024 by 14 Comments

We’ve seen a few retro products using core rope memory, such as telephone autodiallers. Obviously, we’ve covered the Apollo program computers, but we don’t think we’ve seen a complete and functional DIY computer using core rope memory for program storage until now. [P-lab] presents their take on the technology using it to store the program for a Z80-based microprocessor demoboard, built entirely through-hole on a large chunk of veroboard.

For the uninitiated, core rope memory is a simple form of ROM where each core represents a bit in the data word. Each wire represents a single program location. Passing a wire through the core sets the corresponding bit to a logic 1, else 0. These wires are excited with an AC waveform, which is coupled to the cores that host a wire, passing along the signal to a pickup coil. This forms an array of rudimentary transformers. All that is needed is a rectifier/detector to create a stable logic signal to feed onto the data bus.

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No Z80? No Problem!

September 16, 2024 by 17 Comments

Earlier this year Zilog stopped production of the classic 40-pin DIP Z80 microprocessor, a move that brought a tear to the eye of retro computing enthusiasts everywhere. This chip had a huge influence on both desktop and embedded computing that lingers to this day, but it’s fair to say that the market for it has dwindled. If you have a retrocomputer then, what’s to be done? If you’re [Dean Netherton], you create a processor card for the popular RC2014 retrocomputer backplane, carrying the eZ80, a successor chip that’s still in production.

The eZ80 can be thought of as a Z80 system-on-chip, with microcontroller-style peripherals, RAM, and Flash memory on board. It’s much faster than the original and can address a relatively huge 16MB of memory. For this board, he’s put the chip on a processor daughterboard that plugs into a CPU card with a set of latches to drive the slower RC2014 bus. We can’t help drawing analogies with some of the 16-bit upgrades to 8-bit platforms back in the day, which used similar tactics.

So this won’t save the Z80, but it might well give a new dimension to Z80 hacking. Meanwhile, we’re sure there remain enough of the 40-pin chips out there to keep hackers going for many years to come if you prefer the original. Meanwhile, read our coverage of the end-of-life announcement, even roll your own silicon if you want., or learn about the man who started it all, Federico Faggin.

A black device with a monochrome LCD sits on a wooden table. It's keyboard extends below the frame. On the screen is the "Level 29" BBS service login.

Internet Appliance To Portable Terminal

August 8, 2024 by 2 Comments

Few processors have found themselves in so many different devices as the venerable Z80. While it isn’t powerful by modern standards, you can still use devices like this Cidco MailStation as a terminal.

The MailStation was originally designed as an email machine for people who weren’t onboard with this whole computer fad, keeping things simple with just an adjustable monchrome LCD, a keyboard, and a few basic applications. [Joshua Stein] developed a terminal application, msTERM, for the MailStation thanks to work previously done on decoding this device and the wealth of documentation for Z80 assembly.

While [Stein] designed his program to access BBSes, we wonder if it might be a good way to do some distraction-free writing. If that wasn’t enough, he also designed the WiFiStation dongle which lets you communicate over a network without all that tedious mucking about with parallel ports.

If you’d like something designed specifically for writing, how about an AlphaSmart? Wanting to build your own Z80-based project? Why not start with an Altoids-sized Z80 SBC, but don’t wait forever since Z80 production finally ended in June.

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Baldur’s Gate III Comes To The TRS-80 Model 100

June 12, 2024 by 8 Comments

To say that Tandy’s TRS-80 Model 100 was an influential piece of computer hardware would be something of an understatement. While there’s some debate over which computer can historically be called the “first laptop”, the Model 100 was early enough that it helped influence our modern idea of portable computing. It was also one of the most successful of these early portables, due in part to how easy it was to write your own software for it using the built-in BASIC interpreter.

But as handy and capable as that integrated development environment might have been, it never produced anything as impressive as this Baldur’s Gate III “demake” created by [Alex Bowen]. Written in assembly, the game’s engine implements a subset of the Dungeons & Dragons Systems Reference Document (SRD), and is flexible enough that you could use it to produce your own ASCII art role-playing game that can run on either a Model 100 emulator like Virtual-T or on the real hardware.

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CP/M On An Eight Line Display

May 13, 2024 by 5 Comments

How many lines do you need on a CP/M terminal? More is usually better, of course, but the MicroOffice RoadRunner managed with an 8-row, 80-column LCD screen. That may sound anemic, but in 1983, it was high-tech, as was the RoadRunner, and [Tech Time Traveller] tells us about them in a recent video you can see below.

The intro to the video shows some really strange old laptops before it gets to the RoadRunner. The machine used a Z80 work-alike CPU and a form of CP/M with some organizer functions. The machine didn’t have floppies or other disk storage, but did have four cartridge slots that could hold more memory, a spreadsheet, BASIC, or a text editor. The memory cartridges were static RAM with battery backup, so they retained data when you pulled them from the slot. Assuming the battery didn’t die.

Inside a RoadRunner cartridge.

Unfortunately, this particular machine suffered some shipping damage. In addition to the cartridges, it also had a removable battery and modem. At around the eight-minute mark, the case comes off, and inside are — surprise — more internal cartridges.

While MicroOffice isn’t a household name today, it was founded by a former Exxon executive and tapped a CEO and investor from Timex. It was funded by the likes of Olivetti. The computer rolled out in late 1983 and lived until Telxon bought MicroOffice in 1985.

Attempts to run Zork were not fruitful. There really wasn’t enough memory, and file transfer was a bit wonky. If you want a modern Z80 laptop, we know of one with 16 cores. As clunky as the RoadRunner looks, it still beats the old suitcase computers.

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Protoboard Z80 Computer Teaches The Basics

May 11, 2024 by 16 Comments

As curious people, we’re all incredibly fortunate to live in an age where information can so easily be obtained. If you want to learn how something works, from a cotton gin to an RBMK reactor, you’re just a few keystrokes away from articles, diagrams, and videos on the subject. But as helpful as all of that information can be, we also know that there’s no substitute for hands-on experience.

While we can’t recommend you try building a miniature graphite-moderated nuclear reactor, there’s plenty of other devices that you can study by constructing your own functioning model. For example, when [Jorisclayton] wanted to really know what was going on inside a computer, they decided to go back to basics and build their own Z80 machine. To maximize the experience, they skipped any of the existing kit designs and instead wired the whole thing up by hand across a few perfboards.

The main board contains a 4 MHz Z80 processor, paired with 32K ROM and 64K RAM. Here you’ll also find the clock generator, I/O decoder, serial port, voltage regulator, and a trio of expansion slots that use a long strip of 2.54 mm pin headers as the interface. In the first expansion slot you’ve got a primordial “graphics card” based around the TMS9918 video display controller (VDC) and 16K of additional RAM. The second expansion card has a CompactFlash reader and an LED array mapped to I/O address 0x00h so it can be used for various notifications.

[Jorisclayton] says the final expansion board is still being worked on, but the idea is for it to handle user input through a PS/2 keyboard connector, as well as provide ports for a pair of Super Nintendo (or compatible) controllers. Everything is held together with a minimalist 3D printed frame to show off all that careful soldering.

Obviously there’s no PCB design files to share for this one, but [Jorisclayton] has posted a schematic for wiring everything up if you’re looking for resources to build your own Z80 computer. Sure the chips themselves might no longer be in production, but that doesn’t mean this venerable CPU is going anywhere just yet.