The Scoop: Examining the ACA500

For the past two hectic months, I've been involved in part of the development and testing for this accelerator for the Amiga 500 and 500+. Since the product is solid and nearing release and Individual Computers has given me the go-ahead to talk about it, I will list the already known features and a few that have been added - and generally, what it's like to use.

I will try to gather questions about features I've not covered, and update this article to be as complete as possible. You can also email them to "contact at scoopex1988 org". I will also try to answer questions about special uses or combinations in a follow-up article. 

(Last update 2013-12-20 22:05 CET: Added links to FitzSteve's stuff, check it out!) 

This arrived in my mail many weeks of testing ago :) Quite handsome, I think - but note the frail stretch of board holding the Zorro connector! This card cannot be shoved in like a GVP harddisk interface. You should take care inserting it.

(Scroll down for more info.) 

A new Amiga expansion in 2013! 

Availability and price

79.90 EUR + shipping

Shipping to webshops as of 6 Dec, available Dec 12 in these fine establishments:


Last weekend Slash/INS (Johan Elm) came on a visit. I had a surprise for him... ;) The ACA500 firmware was already quite close to release by then, so this turned out to be a full weekend of real usage tests. I let him use it without supervision (because sometimes you can 'test too well' knowing more than a newcomer about how it's supposed to be used, and knowing previous changes and only test for those), and we ended up running tons of demos requiring various Kickstart ROMs, using Workbench and WHDLoad, and generally just having fun with it!

Gallery #1 - real usage

For completeness, I took some more pictures of the hardware itself - perhaps not a lot to see here unless you enjoy looking at circuit boards - and it includes the pictures Jens has already shared on Amiga forums. 

Gallery #2 - circuit board pictures

I put a few famous games on the card and tried them in WHDLoad now on Sunday. These ran fine on my stock A500 with just the ACA500: 

Gallery #3 - WHDLoad Games 

I might put in a trapdoor expansion later and try some games requiring 1MB chip also.  

I want to apologize beforehand for not providing the best quality photos! I hope they will tell the story anyway.

Video clip #1 - AsmOne, Workbench, Games

Shows performance (note that I got memory up to 1133KB after this)  

Video clip #2 - Preloading WHDLoad Games

With 1-180K more FastMem freed, I got rid of the OS-switching (doesn't affect loading, just my sensibilities ;)) "Avail Flush" for the win.

Video clip #3 - WHDLoad Coverage

...and now, thanks to Wepl's WHDLoad 17.2, Preload works fine in Workbench, even with a softkicked 3.1, if you have a trapdoor expansion :)

Video clip #4 - WHDLoad Preload in Workbench

This last video goes into more technical detail about this feature, but it should answer all questions you may have about running all the games in WHDLoad as well, and disspell some doubts, my own included :)

Also check out...

FitzSteve's video about using the ACA500 with accelerators

and his great review: 

The A500 is back!    


Main features and performance

* Specs haven't changed and card looks the same as previously released photos. Looks like Jens' release to Vesalia, Amigakit et al at end of November will be kept.

* Except for a secret: ChipMap - this maps a Rev. 6 (and up) A500's 512K expansion to chipmem, instantly upgrading it to 1MB chipmem!  

* Retail price is 79,90 EUR including German VAT of 19%, plus shipping. 

* 14-MHz 68000 - 18% faster than stock A1200 in Sysinfo!

* A1200 accelerator expansion port, if this speed is not enough :)

* Connectors for Network/USB module and Subway/Delfina 

* 2 CF slots: both can be used with Amiga filesystems. The 'aux' CF slot can be disabled, or used with a PC-formatted card for easy file transfers - PC filesystem drivers are built in.

* CF speed: A slow Lexar card gave me 1450MB/s in Sysinfo, while the cream of the crop, Sandisk Extreme III and IV can reach just over or around 2000KB/s. RDB buffers over 66 or so are just unnecessary, they don't increase raw performance.

* 2MB FastRAM, by default maps to the same address as the internal RAM expansion, improving compatibility

* Having IDE in your A500 finally does not rule out loading games and demos from floppy as usual! The cacheless 68000 CPU should provide great compatibility with disk loaders and just load a little faster - and this is also what I have found for every disk I've run. 

* Boot time optimized - Decompresses Kickstart 3.1 to FastRAM in 1.68 seconds. (Kick 3.1 is more compatible than kick 2.0 for games and demos, so there's no drawback at all to having it as default.)

* Ships with Kickstart 3.1 and 1.3 built in (in fact, the motherboard ROM socket can be empty...)

* Softkicks A1000 kick-disks (Kick 1.1, 1.3 tested, my 1.2 disk had r/w errors)

* VBR Move option for compatibility even with "naughty" WHDLoad slaves

* Debug Exception Check option for development

* Two profile slots for saving configurations in flash - f.ex. a Workstation and a Demo/Gaming profile that you can switch between. 

* Very easy firmware updating (should you need it) via CF card and the menu, and you can always backup your ACA500 with only a floppy disk. Boot the disk and it's restored! (Very neat, in my opinion) 

* Excellent menu with 3 languages so far: English, German, and of course the proudest and most magnificent language of them all: Swedish ;)



Workbench features and WHDLoad

* Basically, it runs everything that you have enough chipmem for. There's not enough FastRAM left after softkicking 3.1 to preload multidisk games to avoid blinks while loading, but they will load and play fine, and the Quit-key will work. If blinking is a concern, add trapdoor RAM with priority, or install a physical 3.1 ROM (slight performance loss). 

* Supports WHDLoad Quit-key in all the games I've tried - 1 game did not start, but I have not checked that the game is correctly installed yet.

* More than 1040 KB FastRAM and more than 420KB Chipmem available in ClassicWB after MapROMming Kickstart 3.1 on a stock A500 - both CF slots enabled.

* Spontaneous reaction by Johan: "Hey, it's really fast in Workbench". Expect slightly faster performance than a stock A1200 - the major factor being that the optimized CF transfer loop talks to FastRAM rather than the slower chip RAM in the A1200. If you must have 16 colors and high resolutions in Workbench however, performance on the A500 will suffer.



Demoscene features

* 60-70 demos run, including Northstar Megademo I on A1000 kick 1.1 and Northstar Megademo II on ROM 1.2. A few demos didn't like the 14MHz CPU but not many so far. All the way up to 1994 demos run in Workbench from an IDE CF card. And even some A500 demos released the last few years, but of course compatible code needs no hardware compatibility support... ;)

* About 4x faster speed assembling in AsmOne compared to stock A500, so if you want to use your A500 for coding you don't have to use floppy disks or risk all your sources on an age-old harddisk anymore. (Heads-up: You do have to unplug the ACA to check that the final code performs OK on stock A500s.)


I have NOT tried my Apollo 060 in the A1200 accelerator slot yet ;)  (Mainly because it's been modded to be hardwired to 3.3V on an ATX connector...)



The (only two, but major) drawbacks first:

* Only 2MB FastRAM. Some expect at least 8MB of any expansion, since even the old ones supported that. On top of that, for Workstation and WHDLoad use, 512KB are reserved for kickstart 3.1. The only upside is that the 2MB FastRAM is faster than traditional FastRAM.

* No case, the card sticks out bare from the side of the computer. I'm currently doing what I can to make a case happen for the ACA500, but this may be a dealbreaker for people with kids, drunk friends, or nosy cats in the vicinity of the card :)


I made a temporary case out of cardboard(!) and stylish matte black vinyl adhesive film, until the case happens.


(All this reminds of a Ciarcia's Circuit Cellar article in byte magazine from 1977 (IIRC), where the author built a 20m keyboard+CRT transceiver set, just so he could put the computer in the cellar, where 'a friend wouldn't lean on the processor card'! The article is called 'Come Upstairs and Be Respectable' :D if you get a thrill reading about origins like me and want to find it...)


Fewer demos than expected had a problem with the very fast 68000+FastRAM. Of course, some demos with slow vectors will run at faster speed than originally. If you require perfection, a stock A500 with kick 1.2+floppies+kickstart switch is the only option. That said, you can run older demos made by coders owning A1000's with hacked kickstart disks, if autumn 1987 is not nostalgic enough ;)


WHDLoad support seems really good this far, even with my usual CF card full of mixed slaves, some not updated since 2009. You should not use 1MB versions of slaves if you have an A500, but if you have an A500+, it saves loading time. The game will tell you how much memory it needs.


Loading is heavy on the CPU, and the screen may blank intermittently while loading the game. For most of the games I tried, this was true. If you won't tolerate this, this isn't the WHDLoad dream machine for you. What it WILL do is enable you to play thousands of games correctly and without choppy frame rates - on a (formerly) humble A500. Without this card, or with another card that is not an accelerator, some games will be choppy. With the ACA500, in fact some vector games will be noticably faster and more playable (such as for example Stunt Car Racer TNT).

EDIT: I was wrong. With some more memory freed, the so called "preload" mode kicked in and the games preloaded fine without this OS-switching, see video clips. 


The CF slots 

The CF slots allow easy alignment. They are quite loose, which allows for insertion with very little force. So little force in fact, that I recommend you take care before pushing them in. Maybe I'm just being overly cautious of damaging the pins, the slots seem quite good, and they have worked fine for at least 100 insertions while testing.

The Aux slot supports booting to a FAT-formatted card, and it doesn't matter if you use Windows XP or Windows 7 Pro 64-bit, just insert the card and quick-format with the default Windows settings and put files on it! Very easy.

You should not expect hot-swapping to work for the PC CF card. Jens has gotten it to work, but it's "fidgety" and varies between individual cards of the same brand and model. It worked for 0 of my cards. 

As for supporting many types of cards, I can't fault it. I've never had a single problem, but you may still have a problem card. Somehow, though, I got the impression that it "just works". (If you need to boot a formatted FFS card under kick 1.3 as I do, you must have no partition larger than 1GB, and the last one must start before the 1GB offset on the card. I find a 2GB card with two 980MB partitions is optimal. For all normal uses apart from this special requirement, I foresee nothing unusual.)

The PC-formatted card supports larger CF cards than FFS, of course. 



Overall, the card itself delivers on all its promises as what I call an "Enabler" - to make a humble A500 seriously usable - and compatible. I'm absolutely thrilled to bits that Jens changed his features and design from the original ACA520 concept. This card is much better. Definitely more usable to me and other A500 users than the usual accelerator with its compatibility problems for running all the things on the original platform. The computer that we fell in love with and that just completely changed our notions of what we thought a home computer could really be.

I've for years wanted to see what I call an "Enabler" for A500 happen, and I was seriously surprised and let down when Jens prioritized Indivision MKII in its place. But he's come good and delivered what some minds may call just a platform to sell more goodies. But the point is goodies are available now for the A500. Who will be the first to build an A500-060 with USB and Internet? :) (Some rich guy who hates ye good olde demos, probably. Hehe.) But even stock, it's already better and has more options than the A600 and A1200. I hope it will get some computers out of parents' attics and the A500 will get the "second coming" it deserves :) 

p.s. It would be unfair to not mention the current competing product - kipper2k's IDE+RAM board. If you want to keep things pure 7MHz 68000, go for it! (I've pre-ordered two...) It won't currently give you chop-free WHDLoad games or full WHDLoad support, and requires a small mod to support Kickstart 3.1 for Workbench use, but it's internal and pretty easy to put inside your A500, saving table space. With a Kickstart Switch installed also, it should give even better support for A500 demos than the ACA500 - except for a few really old demos from 1986/1987 that require special A1000 kickstart disks.







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