Building the perfect A2000: Part 5

In the last installment, we celebrated 1993 with a shiny new graphics card and an operating system update to our Amiga 2000. We’d successfully fended off the Amiga 3000 some time ago, but browsing any productivity-focused magazine around now would have plenty of mention of the elephant in the room: The Amiga 4000. Released in late Autumn 1992, serious users were starting to look to this new flagship for their ultimate Amiga needs. Let’s take a moment to pause and re-evaluate our position in the light of this new contender.

(If you’re only just dipping in to this, why not start with the previous parts? You can skip back to Part 1 where we buy the machine and fit some memory, Part 2 for a hard drive or Part 3 for CPU upgrade and Part 4 is where we sorted out the graphics)

The A4000

It’s probably fair to say the innovation at Commodore was starting to run out a little as we moved into the 90s. Where the A1000 was ground-breaking, and the A500 brought that technology into the home in a really convincing way, the A3000 had fallen a little flat – designed for professionals, it was a little out of reach of the high end consumer market who rightfully wanted that feel of the 2000, but with some sensible upgrades. And as this series has hopefully shown, many of those power users already had a tricked out 2000 which wasn’t worth parting ways with.

So it was with some nervousness that dealers stocked the 4000. It looked great, far more compact and with the same whiter colour of the A600 and A1200. But gone was the A3000’s SCSI, gone was the scandoubler, and what was on offer was a decidedly average machine. The Zorro system was identical to the 3000, no upgrades there, so the only real improvement present was a faster processor; the base model A4000 came with a 25MHz 68030 (the same as the top-end A3000), and then there was a 25MHz 68040 model for those willing to spend another chunk of cash. Admittedly this is a nice upgrade, the CPU is typically twice as fast at the same clock speed, but the ability to use PC monitors was now going to cost you extra, and all your SCSI devices needed an extra controller purchasing too. The A4000 came with the cheaper IDE port offering similar speed – on an unexpanded system at least – but fewer devices, both in quantity and choice.

It also seems that there was a bit of to-and-fro on the specifications quite late on in the development. Even when the A4000 was revealed by magazines, such as Amiga Format Issue 41 (Page 40-42) it listed a Scandoubler as being present, and the basic processor on offer was a “68EC040” – as we now know, this transpired to be a 15KHz only machine just like the A500/600/1200 with a 68030 being the lower specification point.

The last selling point was the new AGA chipset. However, this really was more of a selling point for the games-orientated A1200 and CD32 where number of colours on screen in a platform game is what sells machines. Many productivity users would have found AGA too slow, especially for graphics work, once you went to the higher resolutions. An 800×600 screen is pushing far more data around than the 320×256 we’re used to – over 4 times as much, and some parts of the chipset just hadn’t been upgraded enough to make that smooth. It also really highlighted that missing scandoubler by making an expensive multisync monitor a necessity instead of a more affordable PC type.

At this point, I think we would be quite happy to sit back and not panic. Sure, we’ve spent a lot of money – over £5000 by this point spread over a number of years – but we’ve got a processor that’s roughly as fast as the higher-end version of the A4000. We’ve got a hard drive, we’ve got more memory by far, and we’ve got that important graphics card. To make a better machine is still going to take a sizeable amount of cash, starting with that £2400 machine and then adding another graphics card and some more RAM for a spend of over £3000. Let’s not worry just yet, let’s go back to the plan and see where we end up.

Stage 7: Frikkin’ Lasers

Walking into a PC retailer in 1993 and you’d start to see some fairly impressive new technology – CD-ROM. The idea of storing data on CDs had been around a while, but economies of scale had well and truly taken over by now and a mid-range PC would now often include a drive without adding a scary amount of money to the price. Luckily for us, CD-ROM was born as a platform-agnostic format and wasn’t tied to any particular operating system and you know what that means by now. Just like shopping in a PC magazine for RAM to go on our accelerator, or a SCSI Hard Drive, Amiga owners can pick up a nice affordable CD drive; and because they could do that, Amiga publishers started to see some possibilities.

Now this is not the first time an Amiga would meet optical media. The CDTV was released in 1991 (+100 pedant points if you’re already headed to the comments box to tell us it was originally marketed as a Commodore device, but the ban on retailers associating it with Amiga branding did relax later) and the A570 add-on drive followed shortly after. But these were designed as multimedia devices, to load a CD such as a simple game or encyclopedia. The CDTV didn’t have an official hard drive add-on, as it didn’t suit the Hi-Fi stack use intended by Commodore, and if you plugged an A570 into an A500 you used the port that the hard drive needed. So these CDs were standalone, rather than add-ons for an operating system. You used the CD instead of a floppy disk, to launch a game or program – and when you were done, you swapped the disc and loaded another one from scratch.

Because our A2000 boots from hard drive, a CD-ROM would be more of an add-on to let us browse media like a large, real-only floppy drive rather than using a dedicated application. A great example of this is the Aminet CD, a disk-based mirror of the Aminet file repository that started in early 1992. Starting in 1993 they began releasing CDs, with the first being a snapshot of the FTP site and then subsequent CDs being any updates and then music mods, animations and even full commercial programs to fill the CD. Rather than the CDTV where you boot from a CD and use purely the content within, when you add a CD drive to an Amiga with a hard drive you can swap disks and browse much like you’d expect to on a more modern computer and in the coming years many software collections were released on CDs, and magazines were full of adverts for discs of maybe £15 containing hundreds of disks worth of public domain software. It was probably time for PD sellers to get nervous!

So to accomplish this, we’re going to need some new stuff. First up is the CD drive itself, and in 1993 we’d be looking at a dual speed drive. Each 1x is roughly equivalent to 150KB/sec, which is around 5x the speed of an Amiga floppy disk so a dual speed would be 10x as fast. It’s more than capable of loading programs and copying the sorts of files that Amigas work with – typically things that would fit well on floppy disks – and Commodore even created the CDXL format for streaming (admittedly small) videos direct from CD.

Thankfully for us, this drive has a SCSI interface so plugs nicely into our existing controller. At this point in time, the PC CD drive market was a bit fragmented and as well as SCSI drives there were also Mitsumi and Panasonic drive interfaces, and IDE which would eventually become the standard. A PC sound card for a while would typically have three different interfaces, the ultimate in hedging bets (although notably the CDTV did use a variation on the Mitsumi interface) but SCSI drives were readily available due to the adoption by Apple computers and availability of PC SCSI controllers too.

For this project, a drive was sourced from eBay albeit a Quad Speed model due to availability. They’re really not expensive as people building retro PCs tend to steer clear so demand hasn’t outstripped supply like it sometimes does with other retro hardware. The CD drive slots nicely into the lower drive bay, and the blank cover is unscrewed and kept safe. As a bonus, the drive we’re using was chosen as the fascia colour is a close match to the A2000. A couple of screws each side will secure it in place, and the A2000 has a pair of molex power connectors, one of which we can connect to the drive. Then you just need to connect the data cable – this is a bit more unweildy to route across the 2000 from the hard drive controller but there’s enough space when it’s laid flat over the other cards. You’ll remember we have an Oktagon “hard card” with the HDD mounted directly on it, and the cable in use for that is a really short one that only needs to go an inch or two. That needs swapping for a new one, from the controller, into the hard drive with the same spacing, but then extending much further across to the CD drive. Right angle folds are your friend here and make the wide 50-pin cable more easy to manage than just bundling it up.

This does bring to light the flexibility, and also some of the dangers of SCSI. You can have up to 7 devices attached to one host controller, which is great compared to IDE which featured in the A4000 we covered at the start of this article where the limit was 2, without some fancy interface boards. The cabling can cause a few issues, SCSI cables are wider and often thicker due to the more industrial nature of the build quality, so it can be a challenge to get multiple drives into any machine let alone an A2000. The other watch-out is that each device needs a unique ID from 1-7, set by jumpers (with 0 usually being the controller) but also the devices on each end need to be terminated. In this case, that means the HDD needs to be removed from the controller card as it’s currently the last drive, and hence has the termination jumper set – this needs removing, and termination needs to be set on the CD drive instead. It’s often easier to add devices to the middle of the chain, but in this application that would mean a lot of cable to try and get inside! Whilst you’re doing this, it’s an idea to check the HDD’s ID number and make sure the CD is set to something else.

For more information on the SCSI Bus, Warren Block’s excellent SCSI Examples document has been my go-to for years.

The only other bit we need is some software. We’re running Workbench 3.1 as of the last instalment, and effectively it’s the same as 3.0 which was installed from the factory on the new AGA machines. One of the additions over 3.0 however was rudimentary support for CD drives – and the way this works is a really nice result of the modular nature of how the operating system supports storage. As of Workbench 2.0 there’s a series of files that live in Devs:DOSDrivers, each one of which describes a drive available. All you need is this file and then a “filesystem” (which live in the L folder) – for which Commodore provided a “cdfilesystem” – and you’re ready to go. The DOSDriver describes the geometry of the drive which tells the Amiga how big it is and also holds the details of where to find the drive – according to our diagram above, it’s oktagon.device unit 4. The filesystem driver tells the Amiga how to talk to the drive, and it all comes together wonderfully.

However, we’re not going to stop there. We want the best of the best! Because of this modular nature of DOSDrivers we can swap out parts as we see fit, and here we can replace the Commodore cdfilesystem driver with something a bit more polished.

We’re going to use AsimCDFS, a CD File System that comes as a commercial product. Other pieces of software are available such as AllegroCDFS or CacheCDFS but Asim is well regarded, and of the right era for this machine. One advantage of being a professional package is that it comes with a full installer and support files, where some hobbyist projects might just be a collection of files that you’re meant to know what to do with. Run AsimCDFS’s installer and it offers to find your CD drive (simply select the name of your SCSI controller in the list), and then sets up the DOSdriver mountfile we talked about earlier.

And then…. success! A reboot later and we’re up and running – pop a CD in the drive and an icon appears, and the disc can be browsed just like any floppy or hard drive. It’s not fast, of course – the seek times especially are closer to seconds than milliseconds, but that’s a small price to pay for around 800 floppy disks worth of content on one shiny disc. A quick test with a Euroscene demo disk shows it works just like any other Amiga drive, albeit with the title bar showing 621MB in use – a good deal larger than the hard drive we have!

But why not just use the built in CD drivers supplied by Commodore? Well, AsimCDFS comes with a few goodies – such as the AsimTunes program which is a simple tool to play audio tracks, with the repeat, random and intro scan features you’d expect. This could easily be replaced with another tool if you wish, since those player commands are a standard that all drives work with. Normally the audio will be processed by the drive’s internal digital-to-analogue converter and output from a connection on the rear of the drive which you’ll need to somehow connect to an amplifier. However some drives, such as this Compaq unit, can transfer the digital audio over the SCSI cable; it is then processed by the Amiga and output through the normal channels. The end result is that speakers plugged into the Amiga audio output will be used to play CD audio; during testing it appears that it is somewhat CPU dependent, since the machine seemed a bit laggy and also the quality was slightly lower than you’d expect from a modern machine, which is to be expected since the 16 bit audio is being played through Paula’s 8 bit output. Asim suggest a 68030 is the slowest Amiga you should try this on.

The one things we can’t do, is boot from CD natively like a CDTV would – the drivers don’t exist at boot time and are loaded later. AsimCDFS does have a facility to work around this though – if you pop in a CDTV disk, not only can you browse the files on it but you can also use the SimBoot tool to launch it. In the screenshots here you can see this was put to good use with a game of Xenon 2, although an experiment with my only other CDTV title, the Welcome disk, was less successful with an odd colour scheme and a shift to the left. Also it should be noticed that there was no music playing; possibly because the CDTV would be using the analogue outputs from the drive and I hadn’t got those connected after the CD player testing above.

The cost associated with this upgrade in today’s money was around £25 for a secondhand drive, which just happened to be the right colour for the A2000, and you could probably expect to pay no more than £10 for a custom cable to be made to suit as the spacing needed for a hard card – two connectors close together and a long gap before the third – isn’t an off-the-shelf item. In 1993 the cost for the drive would have been around £300 – interestingly it was very hard to find a bare drive for sale in the Amiga magazines, so a dip into a period PC magazine was needed. And that’s pretty much it, as we already have the SCSI controller we have no further outlay if we chose to use the standard Workbench 3.1 CD Filesystem. In the 1990s if we instead preferred to use AsimCDFS then the RRP on that was £49.99, sadly it is impossible to purchase either that package or an equivalent one in modern times so a repository like TOSEC is your friend.

To close off this installment, let’s look at costs. We started at £5084 total spend since the A2000 was purchased all those years ago, and this upgrade has added a fairly modest amount; £360 including the software, taking us to £5444. In terms of modern spend, our £863 start price has increased by just £35 for a total of £898.

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