Retrocomputing

1675 Articles

Programmable Ruler Keeps 1970’s Computing Alive

March 2, 2019 by 23 Comments

A ruler seems like a pretty simple device; just a nice straight piece of material with some marks on it. There are some improvements out there to the basic design, like making it out of something flexible or printing a few useful crib notes and formulas on it so you have a handy reference. But for the most part, we can all agree that ruler technology has pretty much plateaued.

Well, not if [Brad] has anything to say about it. His latest creation, the Digirule2, is essentially an 8-bit computer like those of the 1970’s that just so happens to be a functional ruler as well. Forget lugging out the Altair 8800 next time you’re in the mood for some old school software development, now you can get the same experience with a piece of hardware that lives in your pencil cup.

Even if you’ve never commanded one of the blinkenlight behemoths that inspired the Digirule2, this is an excellent way to get some hands-on experience with early computer technology. Available for about the cost of a large pizza on Tindie, it represents one of the easiest and most cost-effective ways to tell your friends that as a matter of fact you have programmed a computer in binary.

The Digirule2 is powered by a Microchip PIC18F43K20, and is programmed by punching binary in one byte at a time with a bank of eight tactile switches. To make things a little easier, programs can be saved to the internal EEPROM and loaded back up just as easily thanks to the handy buttons next to the power switch. Now all you’ve got to do is figure out what all those blinking LEDs mean, and you’ll be in business.

The original Digirule was a logic gate simulator that we first covered back in 2015. We’re always happy to see projects grow and evolve over time, and think this new retro-computer themed variant is going to be quite popular with those who still love toggle switches and blinking lights.

Continue reading “Programmable Ruler Keeps 1970’s Computing Alive” →

The 8-Bit Guy Builds A 16-Bit Computer

March 2, 2019 by 90 Comments

One of the better retro historians out there on YouTube is the 8-Bit Guy, and after years of wanting to do something like this, it’s finally happening. The 8-Bit Guy is building his dream computer, heavily inspired by the Commodore 64.

Before we go into what this computer will do and what capabilities it will have, it’s important to note the 8-Bit Guy is actually doing a bit of market and user research before dedicating a year or more to this project. He’s asked other famous retrocomputing YouTubers for their input on what their ‘dream’ retrocomputer should do, and they’ve come up with a basic list of requirements. The Dream Computer will be like working on a 1957 Chevy, in that all the registers are immediately available for peeking and poking. The computer will be completely comprehensible, in so far that one person can completely understand everything, from the individual logic gates inside the CPU to the architecture of the kernel. It’ll run BASIC.

In the age of the Raspberry Pi, one might ask, ‘why not go with a Raspberry Pi?’. To the 8-Bit Guy, the Pi is just a Linux computer. Other retrocomputing projects of a similar scope to this dream computer also fail: The Mega65, a project to resurrect the Commodore 65, will be too expensive. The BASIC Engine fails because it only does composite out, and it runs on an ESP anyway, so you’re shielded from the real hardware. The same problem exists with the Maximite in that the hardware is one layer of abstraction away from the interface. The C256 Foenix is probably the closest to meeting the design goals, but it’s far too expensive, and even without the MIDI ports, SID chips, and other interesting hardware, it would still be above the desired price point.

The ‘requirement’ for this dream computer is to use only modern parts, have VGA or HDMI video out, a real CPU, preferably a 6502, use no FPGA or microcontrollers, and can run Commodore Basic. Also, this computer would cost about $50, with $100 as the absolute, maximum limit (implying a BOM cost of around $15-$25). This is absolutely, completely, astonishingly impossible. I would be deceiving you if I did not mention the impossibility of this project happening with the stated goals. This project will not meet the goal of selling for less than one hundred dollars.

That said, there’s no harm in trying, so The 8-Bit Guy is currently working with a few dev boards, specifically one designed around the 65816 CPU. The 65816 is an interesting chip, in that it is a 6502 until you flip a bit in a register. It has a larger address space than the 6502, and everything from the World of Commodore should be (relatively) easily ported to the 65816. Why was this CPU never used in Commodore hardware? Because a Western Design Center sales guy told a Commodore engineer that Apple was using it in their next computer (the Apple IIgs). The option of Commodore ever using the ‘816 died then and there.

If you’d like to help out on this computer, there is a Facebook group for organizing the build. This Facebook group is a closed group, meaning you need a Facebook account to login. Unfortunate, but we’re looking forward to a year of updates around this dream computer. Building a computer that meets the specs is impossible, but we’re more than eager to see the community try.

Continue reading “The 8-Bit Guy Builds A 16-Bit Computer” →

Flux Engine Reads Floppies

February 19, 2019 by 49 Comments

It is a bit of a paradox that we are storing more and more information digitally, yet every year more and more of it is becoming harder to access. Data on a variety of tapes and disks that were once common, is now trapped on media due to lack of hardware to read it. Do you have a ZIP drive? Do you have a computer that it will work with? Floppies are problem too. You might think you beat the system just by having a USB floppy drive. While these do exist, they typically won’t read oddball formats. That is, except for Flux Engine, an open source USB floppy drive.

The device uses a $15 Cypress development board and just some wiring (along with a 3.5 or 5.25 floppy drive, of course). Currently, the firmware only supports read only access to IBM standard disks and Acorn DFS/ADFS disks. It can also read and write Brother word processor disks. However, being open source, it could do more. The author, [David Given], is looking for Commodore 1541 and Apple CLV disks to borrow so he can get those working. He’s also offered to entertain other formats if you are willing to loan him a disk.

The software uses libusb and is known to work on Linux and Windows with Cygwin. It should also work with OSX. However, you will need a Windows box of some sort to build the Cypress firmware because the Cypress tools won’t work anywhere else. [David] wants to change processors because of this, but if he does, he’ll miss the PSoC function blocks, we are guessing.

The design is actually rather simple. The firmware only measures the time between flux transitions and sends them to the attached PC. All the heavy lifting occurs on the PC, which means it should be pretty easy to analyze and decode new formats. While writing is possible, it appears there is more work that needs to happen to make it reliable. [David] comments that you really need a real drive to test your writing with so you don’t write things only you can read back. Makes sense.

This certainly is more user-friendly than the last method we looked at. We had to wonder if [David] has thought about 8-inch floppies.

The Rotary Joystick Can Take A Beating

February 18, 2019 by 13 Comments

It’s a well-known fact amongst the older set that games used to be harder. Back in the 1980s, most home computers had awful keyboards, barely adequate joysticks, and the games had to be difficult to have any longevity, because there’s only so much you can fit into a single sided disk. Some of these games became known as joystick killers, due to the repetitive thrashing movements required to win. [Jan] was tired of letting Decathlon and its ilk get the better of him and his controllers, so built a joystick that was up to the task.

The basic concept of [Jan]’s rotary joystick is that many games required a fast and repetitive left-right motion to be executed by the player, but weren’t too concerned if a few up or down movements were in the mix. Thus, instead of a traditional shaft-based joystick, instead a rotary mechanism was employed. The player rotates the joystick’s wheel, which has a magnet fitted. This triggers a series of four reed switches, for up, down, left and right. By rotating the wheel quickly, it simulates the rapid left-right motion well enough to beat most of the vintage C64 games that were giving [Jan] trouble, and it makes an ideal controller for the 2018 release, Crank Crank Revolution.

We like the spirit behind any build that uses hardware to overcome intractable gaming problems. We’ve seen similar approaches used to beat Guitar Hero. Remember Guitar Hero? That was a thing. Video after the break.

Continue reading “The Rotary Joystick Can Take A Beating” →

A Network Card For The Trash-80

February 11, 2019 by 16 Comments

Around these parts, [Peter] is well-known for abusing the TRS-80 to do things it should never do. You can read Wikipedia on the TRS-80, you can look at Google Images, and you can browse the web. As with any retrocomputer, there are limitations for what you can do. To browse Wikipedia, [Peter] had to set up an AWS instance which translated everything and used serial to IP converters. It can be done, but it’s hard.

Now, after seeing a few interesting projects built around the ESP32, [Peter] built a network card for the TRS-80. It’s called the trsnic, and it’s a working network card for almost all the TRS-80s out there, with the eventual goal of supporting the TRS-80 Model I / II / III / 4 / 12 / 16 / 16B and 6000.

The idea for the trsnic comes from [Arno Puder]’s RetroStoreCard, a device that plugs into the TRS-80 Model III and connects it to a ‘personal cloud’ of sorts that hosts and runs applications without the need for cassettes or floppys. It does this with an ESP32 wired up to the I/O bus in the Model III, and it’s all completely Open Source.

[Peter] took this idea and ran with it. Thanks to the power found in the ESP32, real encrypted Internet communication can happen, and that means HTTPS and TLS.

Right now, documentation for the trsnic is limited, but the project does exist and building it is as easy as stuffing some headers and DIP sockets in a PCB and soldering them on. There’s a bit of work to do on the ESP32 code, but if you’re looking for a network card for your Trash-80, this is the one that works now.

In Soviet Russia, Computer Programs You

February 7, 2019 by 18 Comments

We admire [Alex Studer’s] approach to schoolwork. His final assignment in his history class was to do an open-ended research project on any topic and — this is key — using any medium. He’d recently watched a video about how Tetris came from the former Soviet Union, and adding in a little eBay research set out to build a period-accurate Soviet computer replica. The post covers the technical details, but if you want to read the historical aspects the school paper is also online.

The first decision was what CPU to use and [Alex] picked the U880 which is a Soviet Z80. All the usual parts you would use with a Z80 have U880 equivalents, so that fleshed out the rest of the design. There were a few concessions made. Instead of a bulky analog monitor, the replica uses an LCD display. Instead of an audio cassette recorder, the new machine uses a CompactFlash socket. We don’t think those are bad decisions. He also replaced the Soviet EPROMs with modern parts. Although the original parts appeared to program correctly, they were unreliable in operation. [Alex] theorizes that his programmer did not generate enough programming voltage to fully program the cells, so they would pass at the low speeds used by the programmer, but not work in the actual circuit.

Continue reading “In Soviet Russia, Computer Programs You” →

The TRS80 Model 100 Gets A Brain Transplant

February 6, 2019 by 45 Comments

We’ll forgive you if you were busy in the ’80s, and missed the TRS80 Model 100. It was a portable version of the original, ran on four AA batteries, and even had an integrated acoustic coupler which proved handy for workers on the go. However, time is rarely kind, and [Trammell] had come across a non-functional example for just $20. It was time to bring this relic screaming into the modern age.

The motherboard was toast, so [Trammell] decided to wire up a Teensy++ directly to the Hitachi HD44102 display driver chips. Being an older LCD, the display needed a negative bias voltage, so a few diodes, capacitors and a PWM line stepped in to create a charge pump. There was no character generator on board, so the heavy lifting is all handled by the Teensy itself. The keyboard was a simple enough matrix design, so that was wired straight up.

[Trammell]’s work with this iteration got as far as acting as a USB serial terminal, and there was some work done on VT100 emulation. However, according to Twitter, the next stage involves an iCE40 FPGA and some music with which we’re altogether too familiar.

[Trammell] owns a working Model 100, too – employed in some modem experiments, no less.