The Most Inexpensive Apple Computer Possible

November 7, 2024 by Bryan Cockfield 20 Comments

If Apple has a reputation for anything other than decent hardware and excellent industrial design, it’s for selling its products at extremely inflated prices. But there are some alternatives if you want the Apple experience on the cheap. Buying their hardware a few years out of date of course is one way to avoid the bulk of the depreciation, but at the extreme end is this working Mac clone that cost just $14.

This build relies on the fact that modern microcontrollers absolutely blow away the computing power available to the average consumer in the 1980s. To emulate the Macintosh 128K, this build uses nothing more powerful than a Raspberry Pi Pico. There’s a little bit more to it than that, though, since this build also replicates the feel of the screen of the era as well. Using a “hat” for the Pi Pico from [Ron’s Computer Videos] lets the Pico’s remaining system resources send the video signal from the emulated Mac out over VGA, meaning that monitors from the late 80s and on can be used with ease. There’s an option for micro SD card storage as well, allowing the retro Mac to have an incredible amount of storage compared to the original.

The emulation of the 80s-era Mac is available on a separate GitHub page for anyone wanting to take a look at that. A VGA monitor is not strictly required, but we do feel that displaying retro computer graphics on 4K OLEDs leaves a little something out of the experience of older machines like this, even if they are emulated. Although this Macintosh replica with a modern e-ink display does an excellent job of recreating the original monochrome displays of early Macs as well.

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New Release Of Vision Basic: Hot New Features!

September 23, 2024 by Alexander Rowsell 7 Comments

As the Commodore 64 ages, it seems to be taking on a second life. Case in point: Vision BASIC is a customized, special version of the BASIC programming language with a ton of features to enable Commodore 64 programs to be written more easily and with all sorts of optimizations. We’ve tested out both the original 1.0 version of Vision BASIC, and now with version 1.1 being released there are a whole host of tweaks and updates to make the experience even better!

One of the only limitation of Vision BASIC is the requirement for expanded RAM. It will not run on an unexpanded C64 — but the compiled programs will, so you can easily distribute software made using Vision on any C64. A feature introduced in version 1.1 is support for GeoRAM, a different RAM expansion cartridge, and modern versions of GeoRAM like the NeoRAM which has battery-backed RAM. This allows almost instantaneous booting into the Vision BASIC development environment.

Some of the standout features include a doubling of compilation speed, which is huge for large programs that take up many REU segments in source form. There are new commands, including ALLMOBS for setting up all sprites with a single command; POLL to set up which joystick port is in use; CATCH to wait for a particular scanline; and plenty more! Many existing commands have been improved as well. As in the original version of Vision BASIC, you can freely mix 6510 assembly and BASIC wherever you want. You can use the built-in commands for bitmaps, including panning, collision detection, etc., or you can handle it in assembly if you want! And of course, it comes with a full manual — yes, a real, printed book!

One of the nice features of Vision BASIC is the customization of the development environment. On the first run, after agreeing to the software terms, you enter your name and it gets saved to the Vision BASIC disk. Then, every time you start the software up, it greets you by name! You can also set up a custom colour scheme, which also gets saved. It’s a very pleasant environment to work in. Depending on how much additional RAM you have, you can hold multiple program segments in different RAM banks. For example, you could have all your source code in one bank, all your bitmaps and sprites in another, and your SID tunes in yet another. The compiler handles all this for you when you go to compile the program to disk, so it’s easy to keep large programs organized and easy to follow.

If you’ve always wanted to write a game or application for the C64 but just didn’t know how to get started, or you felt daunted at having to learn assembly to do sprites and music, Vision BASIC is a great option. You will be blown away at the number of commands available, and as you become more experienced you can start to sprinkle in assembly to optimize certain parts of your code if desired.

Kernel Hack Brings Windows XP To The 486

June 23, 2024 by Alexander Rowsell 20 Comments

The venerable Intel 486 was released in 1989 as the successor to the extremely popular Intel 386. It was the minimum recommended processor for Windows 98. (Surprisingly, the Windows 95 minimum was a 386!) But by the time XP rolled around, you needed at least a 233 MHz Pentium to install. Or at least that was the case until recently when an extremely dedicated user on MSFN named [Dietmar] showed how he hacked the XP kernel so it could run on the classic chip!

The biggest issue preventing XP from working on earlier processors is an instruction introduced on the Pentium: CMPXCHG8B. This instruction compares two 8-byte values and takes different actions depending on an equality test. It either copies the 8 bytes to a destination address or loads it into a 64-bit register. Essentially, it does what it says on the tin: it CoMPares and eXCHanGes some values. If you want to dig into the nitty-gritty details, you can check out this info on the instruction taken from the x86 datasheet.

Without getting too technical, know that this instruction is vital for performance when working with large data structures. This is because one instruction moves 8 bytes at a time, unlike the older CMPXCHG instruction, which only moves a single byte. Essentially, [Dietmar] had to find every usage of CMPXCHG8B and replace it with an equivalent series of CMPXCHG instructions.

On a side note, the once well-known and devastating Pentium F00F bug was caused by a faulty encoding of the CMPXCHG8B instruction. This allowed any user, even unprivileged users, to completely lock up a system, requiring a full reset cycle!

So [Dietmar] was successful, and now you can run the German version of Windows XP on either a real 486 or an emulated one. The installer is available on the Internet Archive and there’s a detailed video below demonstrating installing it on the 86Box virtual machine host.

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Animated gif of large 1950s computer spitting out a sheet of paper.

Retrotechtacular: 1960s Doc Calls Computers The Universal Machine

December 20, 2023 by Drew Littrell 5 Comments

It’s weird to think that an abacus would have still been used sixty years ago, or so posits the documentary series The Computer and the Mind of Man. This six part series originally aired on San Francisco local television station KQED in 1962, a time where few people outside of academia had even stood next to such a device.

Episode 3 titled “The Universal Machine” was dedicated to teaching the public how a computer can enhance every type of business provided humans can sufficiently describe it in coded logic. Though mainly filtered through IBM’s perspective as the company was responsible for funding the set of films; learning how experts of the time contextualized the computer’s potential was illuminating.

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The Sol-1: A 16-bit Computer In 74HC Logic With C Compiler And Unix-like OS

December 11, 2023 by Maya Posch 15 Comments

Sol-1 system pictured from the front. {Credit: Paulo Constantino)

While the concept of a computer system implemented in discrete logic ICs is by itself not among the most original ideas, the way some machines are executed certainly makes them stick out. This is the case with [Paulo Constantino]’s Sol-1, which not only looks extremely professional, but also comes with a lot of amenities that allow for system development, including a C compiler and assembler, a Unix-like OS (in development), DMA, and a whole host of interfaces to interact with the system and peripherals (serial, parallel, IDE, etc.). Not to mention a SystemVerilog model and an emulator, all of which can be found on [Paulo]’s GitHub.

More photos and videos can be found on [Paulo]’s YouTube channel, as well as the Sol-1 website, which shows off the intricate wire wrap work on the back of each PCB. In terms of the ISA, there are 5 general purpose registers (one scratch) which can also be used as two 8-bit registers each. Most operations are supported, except for floating point. For future improvements and additions, Sol-1’s OS will get more features added, and the first major software to be ported to the Sol-1 should be Colossal Cave Adventure and similar text-based adventure (dungeon) games.

A Heathkit H8 in which hides an 8008 instead of the normal 8080

Downgrade Your Heathkit H8 To The World’s First 8-bit Microprocessor

September 6, 2023 by Julian Scheffers 10 Comments

Typically when you’re replacing parts in an old computer it’s either for repairs or an upgrade. Upgrades like adding a more capable processor to an old computer are the most common, and can help bring an old computer a bit closer to the modern era. [Dr. Scott M. Baker] had a different idea, when he downgraded a Heathkit H8 from an 8080 to an 8008.

Despite the very similar numbers, the 8080 runs at four to nearly sixteen times the speed of its predecessor. In addition to this, the 8008 is far less capable on multiple fronts like address space, I/O ports, the stack and even interrupts. The 8008 does have one thing going for it though: the 8008 is widely known as the world’s first 8-bit microprocessor.

A green circuit board with an 8008 and supporting electronics. — The custom 8008 CPU board for the Heathkit H8.

In the video after the break, [Scott] goes into great detail about the challenges presented in replacing the 8080 with the 8008, starting with the clock. The clock is two-phase, so that what would otherwise be a single oscillator now also has a clock divider and two NAND gates.

Boring clock stuff aside, he does some great hacking using the I/O ports including expanding the I/O port count from 32 to the full 256, bit-banging serial, implementing an interrupt controller and even memory mapping 64 KiB into 16 KiB of address space! With that and a few more special adapter circuits, we think [Scott] has done a great job of downgrading his H8 and the resulting CPU board looks fabulous.

Maybe you’re wondering what happens if you upgrade the computer instead of the CPU? What you get is this credit-card sized 6502 computer.

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Fujitsu Proprietary Keyboard Goes PS/2 With A Pico

July 1, 2023 by Jonathan Bennett 8 Comments

One of our favorite retro-computing YouTubers, [Clint] from LGR, found himself a very interesting Fujitsu keyboard while thrift store shopping. It was a beautiful unit, but confusing, as this keyboard comes with an 8-pin DIN connector. A 5-pin DIN plug or 6-pin Mini-DIN would be easy to work with, but what was this odd connection? Turns out the Fujitsu N860-2500-T111 came with an Olympus CV-100 Video Processor, which was designed for medical imaging, potentially among other uses. And as often happened with old specialized hardware, the keyboard used a proprietary protocol for sending keystrokes.

[Clint] put out a call for anyone that could help him build an adapter, and [Andy] from Element14 answered the call. But this problem requires more than an adapter, mainly because the Fujitsu doesn’t have key rollover. It’s one key at a time, and that just doesn’t work for the sort of things [Clint] shows off on LGR. So, the electronic guts of the keyboard were removed, to be replaced with a Raspberry Pi Pico, wired directly to the keyboard matrix.

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