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30th July 2002


Gavin Haines


(This article was first published in the ICPUG Journal January/February 1993 issue.
Permission from Gavin Haines to republish on the Internet has been received.)

My room is already like the Starship Enterprise. I am not sure I want yet another machine, but resistance is useless. With two machines you can have the best of both worlds, (as Captain Picard found out). The computer industry, like the Borg, is the ultimate user.

There are two obstacles in personal computing, time and money. You can, to a certain extent, offset a deficit of one with a surplus of the other. By spending more time, you can spend less money and vice versa. The extent to which you can offset a deficit of money is called 'compatibility'. The extent to which you can't is called 'marketing'.

What does Compatibility mean?

The Amiga A600 is an enhanced version of the A500, but is it fully compatible? Of course it isn't. If it were, it would be an A500 and what would be the point?

There are two kinds of incompatibility - hardware incompatibility and software incompatibility. Hardware designed for the A500 may not work in the A600 and vice versa for two basic reasons: either it won't fit, or the software required for the hardware won't run on the other machine.

The most likely software incompatibility you'll encounter is that the other machine has a different amount of CHIP RAM. What does this mean? CHIP RAM means Random Access Memory in the main part of the computer. Any additional RAM that you have connected, (to the expansion bus), is called 'FAST RAM'.

The idea is that your program sits in the FAST RAM whilst Gary, Denise and Agnus use the CHIP RAM to provide you with graphics and sound. The original Amiga A1000 had 256K of CHIP memory with an optional 256K expansion card. The A500 had 512K of CHIP memory with an optional 512K expansion. The A600 has 1024K, (1MB), of CHIP RAM with an optional 1MB expansion. So A600 compares to the A500 as the A500 compared to the original machine.

Incompatibility can arise when a program written for the original machine ends up dealing with the wrong area of memory. This can have a number of effects. The program may crash or, if it runs, the results may not be as the application writer had intended. Either way, it's unpredictable.

Workbench 2 is an incompatible release over Workbench 1.3. You usually find that software written for the old machine will run on the new machine and that things are a more difficult the other way around. The main problem with having a new machine is that it makes many old routines and utilities redundant. What was extra under Version 1.3 is built in under Version 2.

The A500 is good for running all the old utilities and games. Your only problem is that you have a machine which the magazines aren't interested in promoting. 'This one only runs under Workbench 2 folks. . . '

The A500 and the A600 have a different keyboards and some software may make assumptions about the numeric keypad. This problem is fairly minor.

The A600 is called a 'cost reduced machine'. It is a mixture of improvements and compromises. It includes the Extended chip set (ECS) Agnus, Denise and Kickstart 2.05 in ROM, but the Gary chip has been replaced by 'Gayle'. This provides new screen modes, as on the A500 plus, but you need a special monitor. There is a standard 880K drive as on the 500, but the 86-pin expansion connector has been replaced with a PCMCIA expansion slot. This is similar to, but not compatible with, the credit card slot on the CDTV. The 600 has a built in IDE interface to which you can connect a 2.5" internal hard drive, but it is incompatible with 500 devices such as the A590 hard drive and the A570 CD ROM.

All the chips on the A600, except the Kickstart ROMs, are surface mounted. This increases reliability, but DIY is difficult if not impossible. The man in the local computer shop told me that 'surface mounted' meant 'assembled by robots'. This doesn't necessarily follow; it just means that the silicon chips are soldered into place.

Dual in-line packages, (i.e. the oblong 'caterpillar' shape), can work loose from their sockets with the continual heating and cooling that results from the machine being turned on and off. The connectors can also oxidise, resulting in poor contacts. The manufacturer doesn't want failures to occur during the guarantee period. The latest microprocessor chips are packaged in a pin grid array, (i.e. a square), which is surface mounted to avoid these problems.

What if I've got an A500?

Well, you can upgrade it, but the complete kit costs nearly as much as the base A600. You can have Workbench 2 on an old A500 and you need to install 'fatter Agnus', (if your machine doesn't already have it), in order to enable 1MB CHIP memory operation. You also need to replace the Gary chip for a complete upgrade allowing you to use all the screen modes on your special multi-sync monitor. You can find out whether or not you already have 'fatter Agnus' by using a utility program such as 'Syslnfo'.

Important: A number of A500s, such as those in the 'Screen Gems Pack', were supplied with ECS Fatter Agnus, Kickstart, and DOS 1.3 in ROM, but with User Manuals for the earlier machine. The outdated User Manual in this case makes you think you have the 8370 Fat Agnus.

The 'Enhancer' manual, (the white book), refers to the AmigaDOS Version 1.3 that was available as a disk-based update for 1.2 version users. In this case, the outdated manual makes you think you have to load a number of AmigaDOS commands in from disk whereas in fact they are available in ROM. Hot tip: With 1.3 in ROM you can get straight into the command line, (as soon as the AmigaDOS window appears after switching on), by hitting CTRL-D.

Should I be thinking of getting the CDTV?

Well, the CDTV certainly looks more professional and it plays audio CDs, if you need an excuse. It has 1 MB of CHIP memory, so many of the old games won't run on it. [Additionally, the CD drive uses some of this RAM, so there is only about 8O0K available, though the amount installed can be increased to 2MB - 1993 Ed] It only has version 1.3 of the operating system.

Should I get the A570 CD ROM instead? This effectively turns your 500 into a CDTV. With more or less the entire Fred Fish collection and other PD libraries available on the CD, you would certainly save on floppy disks. But you need to do the 1MB CHIP RAM modification mentioned on the previous page, and you can't connect both the CD-ROM drive and A590 hard disk [You can add a SCSI card inside the A570. An external SCSI drive may then be used or a 2.5" unit fitted inside the case - 1993 Ed ]

Note that many programs in the Fish collection are in compressed format and you will need to 'unarchive' them to floppy disk. Also note that you often have to do quite a bit of work on the software to install it on your system. [Untrue if you use the CDPD 11 disc from Almathera - 1993 Ed]. Although you have all of the Fish library on-line, you can't use most of it directly from the CD-ROM.

What about the A 1200 and the A4000? It is rumoured that about 70% of old software intended for the A500 et al. will run, but you will probably need to buy new versions of most things if you are to take advantage of the new system's facilities. What's the point of having a new machine, if you are only going to run old software? You might as well have kept the old machine!

Buy now or wait? There is always a new machine around the corner, so if you want the new machine, and have got the cash, I recommend buy now. If you wait, you'll be buying the new machine just as it is about to be superseded by the next machine!

Speaking as someone who has had several computers. . . ( They are supposedly sold, but in reality they are in the cupboard under the stairs ). . . I have found that the 'enhanced' version is often not as good as the original machine. If you don't have both machines you are forced to assume that the software is incompatible with the new machine. If there's a problem, you can't determine the cause of it. Is it the machine? Or is it the software?

If you don't upgrade, most the features of the new machine are available to you in the shape of the old software you would be running! With a ROM sharer you do indeed have the best of both worlds, but being converted into a Borg does get to be a bit of a strain! Commodore's balance of trade is going to hold up, one way or another, so if you do upgrade, keep your original machine.

ED 2002 - The last sentence is amusing to read now and I would not take too much regard of the CDTV. This bombed and was the start of Commodore's demise. However, the general statements about compatibility and when to upgrade are as true now as 10 years ago and just as relevant to PCs or Macs.