Author: Al Williams

4504 Articles

A Retrocomputer Disk On A Chip

March 30, 2018 by 28 Comments

There have been a lot of different mass storage methods over the relatively short lifespan of the computer. Magnetic tapes, drums, all sorts of disks, and flash memory have each had their time. Each of these new innovations required some time to become easy to use. One of the early attempts to simplify using flash memory was the M-Systems DiskOnChip device. Looking like a standard 8K JEDEC-compatible memory device, it actually provided access to a flash disk drive ranging from 16MB to 1GB. [Smbakeryt] bought some of these devices and built an ISA board to provide a disk and clock for the old 8-bit bus. You can see a video discussion about the device below.

SanDisk bought M-Systems and discontinued the devices back in 2007. Of course, you can still design flash memory into your system, but the simple and efficient interface of the DiskOnChip is no more. It is a testament to how simple the interface is that the schematic for the little board fits on a page, including the DS12885 real time clock.

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Oracle V Google Could Chill Software Development

March 30, 2018 by 96 Comments

Unless you’ve completely unplugged from the news, you probably are aware that the long-running feud between Oracle and Google had a new court decision this week. An appeal court found that Google’s excuse of fair use wasn’t acceptable and that they did infringe on Oracle’s copyrights to Java. Oracle has asked for about $9 billion in damages, although the actual amount is yet to be decided. In addition, it is pretty likely Google will take it up to the Supreme Court before any actual judgment is levied.

The news is aimed at normal people, so it is pretty glossy about what exactly happened. We set out to try to make sense of it all. We found a pretty good article from [Michaela Barry] about what the courts previously found.  There were three main parts:

  • There were 37 API (Application Programming Interface) declarations taken verbatim from Java. This would be like a C header file if you aren’t familiar with Java.
  • Google decompiled 8 security files and used them.
  • The rangeCheck function — 9 lines of Java code — were exactly the same in Oracle’s Java and Android.

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Apple One, On FPGA

March 29, 2018 by 17 Comments

Today, Apple is known for iPhones, iPads, and a commitment to graphical user interfaces. But that wasn’t how it all started. The original Apple was a single board computer built around a 6502. In 1976, you could snag one for $666.66, but you needed to supply your own TV, power supply, and keyboard. [Alangarf] didn’t have an Apple 1, but he did have a 6502 CPU core for FPGAs from [Andrew Holme] that he fleshed out to an Apple I clone with a VGA output and PS/2 keyboard port. The project works with either an iCE40 board or a Terasic DE0 board. You could probably port it to other similar FPGAs.

This is much more practical than trying to find an original, as Apple bought a lot of the old boards back and destroyed them. According to the Apple-1 Registry there are only about 71 of the boards still in existence, and that’s with the annotation that 4 of those may be lost and 8 might be duplicates. We’ve heard that of those there are only six that actually still work.

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Forth Version 1 Runs Again

March 27, 2018 by 23 Comments

Some people love Forth and some people hate it. However, you usually think of Forth as something running on a little computer such as an 8-bit microcomputer. When [Chuck Moore] developed the system back in the 1960s though, it ran on an IBM 1130. [Carl Claunch] took a scanned listing of the original code and got it running once again.

There are actually a few blog posts with details. Luckily, Forth is pretty simple — especially the core parts. However, there are a lot of differences from a modern Forth. The most obvious is that the dot keyword starts a definition and does not print the top of stack. However, internal details are different too — the system, for example, stores characters in packed EBCDIC — an ASCII-like code used by IBM computers.

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Everything You Wanted To Know About Transformers (But Were Afraid To Ask)

March 27, 2018 by 18 Comments

[Jim Pytel] has a lot of very good instructional videos on his channel, and he recently added one you’ll enjoy on transformers. You probably know that transformers convert one AC voltage into another AC voltage. Some step up voltage, some step down voltage, and others simply pass voltage through but isolate the input from the output.

The 40 minute video covers basics including how the transformer works, the meaning of the turns ratio, and how transformers reflect impedance. You probably should understand how to compute AC power, but if you need a refresher [Jim] has a video for that, too.

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Retrotechtacular: A 180 GB Drive From 1994

March 27, 2018 by 95 Comments

Hard drive storage has gone through the roof in recent years. Rotating hard drives that can hold 16 terabytes of data are essentially available today, although pricey, and 12 terabyte drives are commonplace. For those who remember when a single terabyte was a lot of storage, the idea that you can now pick up a drive of that size for under $40 is amazing. Bear in mind, we are talking terabytes.

In 1994, that was an unimaginable amount of storage. Just a scant 24 years ago, though, you could get 90 gigabytes — 0.09 terabytes — if you didn’t mind buying an IBM mainframe and a RAMAC disk storage unit. You can see a promotional video digitized by Archive.org, below. Just keep in mind that IBM has a long history of calling disk drives DASD — an acronym for Direct Access Storage Device. You pronounce that “dazz-dee”, as you’ll hear in the video.

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IQ Makes Smarter Motors

March 26, 2018 by 23 Comments

We think of motors typically as pretty dumb devices. Depending on the kind, you send them some current or some pulses, and they turn. No problem. Even an RC servo, which has some smarts on board, doesn’t have a lot of capability. However, there is a new generation of smart motors out that combine the mechanical motor mechanism with a built-in controller. [Bunnie] looks at one that isn’t even called a motor. It is the IQ position module.

Despite the name, these devices are just a brushless DC motor (BLDC) with a controller and an API. There’s no gearing, so backdriving the motor is permissible and it can even double as a motion sensor. The video below shows [Bunnie] making one module track the other using just a little bit of code.

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