(Re)creating new Amigas for the 2020s and beyond

▼ Two forum posts made me think of what it would take to build an Amiga using modern parts, and what should remain the same and what should change about a new Amiga to remain useful in the next decades.

The first is on AmigaLove, a forum that I found recently and that I enjoy participating on: FPGA Custom Chips. The original post is about creating FPGA implementations of the Amiga's custom chips. That way, it's possible to replace the original chips when they fail, or build a new Amiga from scratch.

The other one is on the MiSTer FPGA Forum: Faster CPU for Minimig core?. (Minimig core = Amiga on the MiSTer.)

(An FPGA is a field programmable gate array, or basically a lot of small parts that perform functions used in all kinds of computer chips, and these parts can be connected in different ways so the FPGA can "become" lots of different chips.)

But what should be our goal?

Obviously, some of us, especially those who still have Amigas that we use from time to time, would love to retain access to something as close to an original Amiga as possible. However, then what about the peripherals?

Today, if you bring an Amiga into a home, there's a 99% change that you can't hook it up to a TV or monitor there, and a 99.9% chance you can't exchange any files between the new Amiga and anything else.

So I say: a new Amiga needs to be more like a THEC64 than an actual Commodore 64 (well, actual Amiga). That means: HDMI for video output and the ability to use USB peripherals.

And that's not impossible. I'm typing this on my Amiga 1200 right now, but I'm using an HDMI monitor thanks to the Indivision AGA MK3 adapter and a USB mouse thanks to the MouSTer adapter. And a USB keyboard thanks to the Rapid Road USB adapter, but I readily admit that that's just showing off. (Although the CTRL keyboard types a lot nicer than a 28-year-old Amiga 1200 keyboard.)

What this could look like is just like with the original Amiga generations, two versions: one integrated with the keyboard, and a "big box" model. I think for the integrated one, a case that holds the middle ground between the A600 and A1200 would make sense. Remove the numeric keypad but keep the cursor keys. This is something new, it doesn't have to look exactly like its predecessors. For the big box version I think something that looks like an A3000 but smaller would be great, or maybe even a smaller version of the Amiga 1000 case.

Chipset and floppies

Obviously to run old games, the chipset needs to recreate the A500/A1000/A2000 chips exactly, as seen by Amiga software. So USB peripherals such as mice, joysticks and keyboards must be remapped to recreated versions of the Amiga hardware. I think that also needs to apply to the floppy drive, as so many games and demos had their own floppy drive code. Perhaps the machines should optionally have an actual floppy drive. That way, access to the floppy-based Amiga legacy is guaranteed. But most of the time, an integrated Gotek-like floppy emulator would do the trick.

(And the middle ground: something that physically looks like a floppy drive and accepts floppies and floppy-shaped objects, but then only reads a barcode from the back to mount the right disk image. That would provide the authentic experience without all the issues with actual magnetic storage.)

Ports

On the one hand, it would be great to have all the original ports, but on the other hand, that is more difficult/expensive, for probably relatively little benefit. Let's have a look:

Mouse and joystick ports: it's easy to map USB mice/joysticks to the Amiga hardware. I'm doing that right now. Then again, the hardware is super simple, so perhaps the ability to use the real thing isn't too onerous.

Video: I'd say: just embrace HDMI and leave the past behind. Of course add good scaling and filters and especially handle PAL vs NTSC well. One of the cool things only the Amiga could do is switch video modes on the fly when cycling through screens.

Then again, the MiSTer FPGA platform does support analog video out currently. Could this be an option? But a complete Amiga video connector, genlock-capable and all? Too much to ask, in my opionion. If you really want that, use an original Amiga in good condition.

Audio: one of my complaints about the modern THEC64 is that it only outputs audio over HDMI. That's pretty limiting. Please give us line out for those sweet, sweet MOD files.

External floppy: not sure how difficult this is. But is it useful? For an internal floppy option, a PC floppy drive can be used (the differences are extremely minor and can be accommodated in a recreated chipset), but external Amiga floppy drives are more complex. And one physical floppy drive along with additional emulated ones seems more than adequate.

Serial: there are a few uses for the serial port that are still relevant, I'd say. So having the Amiga think it has a working serial port would be useful, but not sure if having the additional hardware is very necessary. The Amiga's serial port could be mapped to a USB serial port but also be mapped to a network service.

Parallel: well, parallel printers are dead. Not sure if there's any printers left with reasonable Amiga drivers. Intercepting the Amiga's print output and saving it to a file for later display, conversion and then printing to a modern printer makes more sense. But the parallel port was also used for all kinds of interesting stuff, such as the Digiview video digitizer. Not a priority, but on the other hand: just a bunch of GPIO (general purpose IO) pins seems workable.

A1200 hardware

So that's all the ports you'll find on an A500 / A1000 / A2000. But there is more. Next to the A500, the A1200 is the big gaming platform that you'll want to support to let people play AGA games. So:

Harddrive: lots of Amiga software needs a harddrive. And again, I think the right approach is to recreate something that looks like the original Amiga hardware from the software side, but then remaps to modern hardware. I'm thinking an SD card as the harddrive.

PCMCIA slot: used for all kinds of stuff, but mostly to exchange data with other systems on CF cards and for network cards. I would replace this with an (additional) SD card slot. As using CF cards in this slot required extra software anyway, it would be fine to have an extra AmigaOS driver to talk to this SD card slot.

68020: the A1200 uses the 68(EC)020 CPU. So in order to run software made for the A1200, it's necessary to support the 68020.

More advanced hardware

Retargetable graphics (RTG): most non-game software on later AmigaOS versions will happily run on screens powered by RTG graphics cards. These don't have the limitations of the Amiga's chipset. So RTG support that integrates well with the Amiga's native graphics capability would be extremely useful.

68030: the Amiga 3000 uses the Motorola 68030 CPU. The 68030 isn't very different from the 68020, except that is has an MMU. Not a feature that is used a lot by Amiga software, but still useful in some cases. So not a top priority, but nice to have. 68040 and 68060 were a lot faster, but also less compatible. It's probably more useful to make the 68020/68030 implementation faster than to recreate the 68040 or 68060.

FPU: the Amiga 3000 has a 68882 floating point unit, and Amiga 4000s with a 68040 CPU had a built-in FPU. I think in general Amiga software doesn't require an FPU, but there could be situations where not having an FPU creates issues, such as having to use a less capable version of some software.

And an FPU speeds up some software quite a lot. (I think some people doing MiSTer Minimig benchmarks aren't comparing their results to FPU-enabled results.)

Perhaps giving up some accuracy for speed makes sense here, for instance by emulating the FPU (or CPU+FPU) in software rather than use a cycle exact FPGA implementation to run this kind of software.

Last but not least: networking. No original Amiga came with a network card. So recreating old networking hardware doesn't make much sense. However, some way to implement networking functionality does. Not sure if a bsdsocket.library that simply punts network calls to the ARM CPU that runs a Linux variant makes sense, or perhaps something that looks to the Amiga like Ethernet hardware and is then bridged with Wi-Fi. That way, the Amiga can use "real" networking but doesn't have to keep up with changing Wi-Fi (security) standards.

Well, that's my vision of future Amigas. Now the only thing to figure out is what model number they should get. 1600? 5000?

Permalink - posted 2021-08-08

Review: MouSTer: making my favorite wireless mouse work with my Amiga

▼ Original Amiga mice were never that great, and a few decades of use and storage didn't help. So if there's one part of the Amiga I have no problem replacing with something new, it's the mouse. (Don't feel bad, I swore of Apple mice, too.) So a while ago I got a USB-to-DB9 mouse adapter. That one worked fine with wired mice, which was a big improvement.

An Amiga 3000 "tank mouse", an Amiga 1200 mouse and a 2000-era Logitech Mini Wheel Mouse

However, a few years ago I discovered the Logitech Anywhere MX 2 wireless mouse. I liked it so much I got one for at home and one for at work. The MX 2 is a bluetooth mouse that can pair with three computers. You can simply switch to another computer with a small button at the bottom. Now obviously the Amiga doesn't do bluetooth, but the MX 2 comes with a Logitech unifying receiver, which you can plug in any USB port and then the computer thinks it's talking to a wired USB mouse.

Problem solved, right? Not really. The MX 2 didn't work with that adapter, nor with another one. Eventually I went as far as to get a RapidRoad USB adapter for my Amiga 1200. This does work very well most of the time, but the complex USB software is not compatible with most games and is not 100% reliable.

The MouSTer connected to a DB9 extension cable, with the Logitech unifying receiver and the MX Anywhere 2

So when I read about the MouSTer, I thought four times might be a charm. After waiting for the little device to make its way from Poland to Holland over the course of very many days, it arrived today. So I plugged it in and... not much. The mouse pointer did move a pixel or two, but nothing close to working correctly. Then I noticed:

So I plugged a USB thumb drive into the MouSTer, which produced furiously blinking LEDs. Afterwards, there was a new directory on the flash drive, with in it a file named MOUSTER.INI. This is a text file with settings and clear explanations what they do. Out of the box, the MouSTer was set up for the Atari ST (hm, maybe the capitalized ST in the name should have been a clue?). I quickly changed that to "amiga". For good measure, I downloaded the latest firmware and put that next to the MOUSTER.INI file and put the thumb drive back into the MouSTer. After that, different mice worked as expected, with just some tweaks to the DPI divider and LED heartbeat settings needed.

A modern optical mouse like the MX Anywhere 2 sends way more "hey, the mouse has moved" pulses than the Amiga expects. As a result, when you move the mouse quickly, the mouse pointer jumps around because the computer can't keep up. Using a DPI divider ("microstep") value of 2 - 5 on the MouSTer didn't completely solve that for me, but using the Mac Logitech Options program to tell the mouse to use the minimum pointer speed, along with a microstep value of 2 made everything work satisfactorily.

Amiga mice normally have two buttons. The DB9 port has just one unused wire, so the Amiga can recognize a third button, but that's it. No scroll wheels—without using different hardware. However, the MouSTer will helpfully map any additional mouse buttons to the three the Amiga can recognize, with or without autofire. A program like FreeWheel will let you do something useful with the extra mouse button.

You can tell the MouSTer is starting up after turning on the computer because its yellow-orange light flashes furiously. (It'll tell you any error messages in morse code.) This is fast enough that if you press both mouse buttons as you turn on the computer, you're greeted by the boot menu as intended.

Conclusions: after only a few hours of use, I'm already a fan of the MouSTer. The hardware is nice and small, so it doesn't stick out far enough to get in the way. The electronics are visible, but covered with plastic so no chance of accidental shorts. The configuration method is unorthodox, but works well. I tested it with both a wired and a wireless mouse, as well as a couple of joysticks. Everything worked. (It also supports gamepads.) Using the Amiga mouse port is a mixed blessing. On the one hand, it's a limitation: only the one extra middle button and no scroll wheel support. On the other hand, it works with everything. In my case, I simply use two Logitech receivers: one on the MouSTer and one on the RapidRoad. So I just flip the mouse and push a button to switch between features and compatibility. 😎

Permalink - posted 2021-07-24

Iconverter makes your old Amiga icons look right

▼ The way the Amiga handles icons changed a number of times over the history of the platform, with the result that many older icons don't look right on Amigas running later versions of the OS. I made a tool to convert these old icons so they look like they should on later Amigas: Iconverter.

Iconverter is a tool for converting old icons so they look as intended on Amigas running a more recent operating system.

In particular Iconverter will convert OS 1.x and MagicWB icons to NewIcons format using the palette those icons were created for. (Also OS 2.0 - 3.1 icons, but those usually look correct without conversion.)

Note that you need to run the NewIcons extension or the new IconLib_46 on an AmigaOS 3.0 or 3.1 system in order to see the converted version of icons created by Iconverter. AmigaOS 3.1.4 and 3.2 will show them "out of the box".

Iconverter is a shell / command line tool written in standard C. As such, it should compile and run on any system that has a C compiler.

Permalink - posted 2021-07-14

The Commander X16 (and some more BASICODE)

▼ The Commander X16 is an upcoming new Commodore 64 like 8-bit computer built from currently available parts, as explained in Youtube playlist. After watching some of the more recent videos, I decided to download the emulator... and tried out some BASICODE on it.

Why a new 8-bit computer?

Part of this is of course middle aged nerds wanting to relive their childhoods. Not discounting that aspect, I do think there was something special about the 8-bit home computers from the 1980s. Because those systems were so limited, they dispensed with all overhead and just gave you the minimum needed to write and run programs. So it was easy to write programs like games yourself.

And for some reason, for me at least, none of that translated to more modern systems like the Amiga. Not too long after I got an Amiga, I learned C in college, and ended up writing relatively low level code such as my own traceroute implementation. But I never wrote anything that uses the graphical capabilities of the Amiga, PC or Mac. (Unless you count some more recent web stuff.)

Now obviously those old computers can still be found, but it's getting harder and harder to use them, as compatible displays and I/O options are becoming more scarce. Some kind of emulation such as the THEC64 works well to run the old software more easily, but has nothing to do with the old hardware. Part of the charm of those 8-bit computers is that a single person can understand the whole thing, software and hardware.

Commander X16

So that's where the Commander X16 comes in. The basic idea is to start with a VIC-20, which is an extremely simple design with many parts still available, and then update some parts as necessary.

The biggest issue was finding a good graphics chip with abilities similar to the C64's VIC-II chip. They couldn't find any, so they use an FPGA-based video controller instead, with 128 MB of its own video RAM and also an SD card interface for storage. Audio options were also less than ideal, so it looks like they're also going to use the VERA FPGA video controller for audio.

The VERA will output 640x480 analog VGA, with various text and graphics modes.

The CPU will be an 8 MHz 6502. It's really too bad that they didn't choose the 65816, a backwards compatible 16-bit successor of the 6502. The X16 will have 40 kB of regular RAM (minus a bit for hardware registers) followed by 8 kB of "bankable" RAM. That's 512 kB or 2 MB of additional RAM, but the 6502 can't address that much memory, so at any one time, 8 kB of the extension RAM can be mapped into the 6502's address space. The ROM works in a similar way, with one 16 kB bank out of a total 512 kB available at any time.

The X16 will support a PS/2 keyboard and mouse as well as various extension options. Unfortunately, there is no RS232 port or any other way to communicate with the rest of the world included. So that means either an extension card or swapping out that SD card on a regular basis.

They eventually licensed the C64 BASIC and “KERNAL”, so BASIC programs or even machine code / assembly programs that only uses the system interfaces and don't try to directly use the C64 hardware will run on the X16. On the one hand, that's nice because it's familiar to people who've programmed on the C64 and it will be possible to port over C64 programs relatively easily, but on the other hand, even within the limitations of an 8-bit computer there are a lot of things we could do better these days. For instance, the C64 uses a weird variation of ASCII that makes exchanging text pretty annoying.

BASICODE on the X16

So I wanted to see what it would take to run BASICODE on the X16 using the emulator. I didn't know yet they'd licensed the C64 ROMs so I was surprised to see how compatible the X16 really is with C64 BASIC and C64 system calls. For the most part, the only thing I had to do is change my cursor position code a bit to use the official API call rather than jump directly to the KERNAL code.

But... Cursor positioning once again turned out to be my nemesis. Although the C64 has a 40-column screen, when you move beyond column 39, you continue on to 40, 41 and so on, until 79. That way, you can type lines of BASIC longer than 40 characters. So that creates trouble with BASICODE programs try to figure out the size of the screen. For the C64, I just made sure you couldn't go beyond column 39 and line 24.

The X16's default text mode is 80x60 and it can also run in 40x30. So I had to figure out which mode we're in to tell the difference between the actual column 40 on a 80x60 screen, or the face column 40 on a 40x30 screen. BASICODE programs may also try to figure out the size of the screen by specifying line 100 or so and see on which line they actually end up. But specifying a line outside the actual screen hangs the computer (or emulator). So I had to work around that, too. Eventually I managed to do all of that, and that same code now runs correctly on the C64 and the X16 both in 80x60 and 40x30 mode.

I've updated the my C64 BASICODE subroutines here. Here are some BASICODE programs in English. I like Sea Wars, which is a pretty good version of Battleship, which can run in Dutch, English, French and German. This is the PRG file that will run on the C64 or Commander X16: seawars.prg.

Permalink - posted 2021-05-30