Almost all Amigas (with the exception of Phil’s new A1000 – more on that soon!) have a Kickstart chip. This holds a huge chunk of what you see as the OS including device drivers for built in hardware like IDE, serial and parallal ports; Intuition which the part that describes the look and feel, and why booting a Workbench 1.3 disk on a Kickstart 2 machine gives you the grey background as it’s held in ROM; and more. It’s the personality of the machine. It will have come with one from the factory, and you can upgrade this to a newer version by popping the case open and carefully swapping the chip (or chips, in the case of 32 bit machines).
With the release of AmigaOS 3.2 the distribution method has changed and at the time of writing the primary distribution is to be sent the ROM images on a CD which means you’ll need the services of someone to turn that into the physical ROM before you can swap the chips over and enjoy the latest release. Or does it? You could always invest a little bit of money and burn your own; and with the licence for AmigaOS 3.2 permitting you to buy once and burn for all your Amigas then owners of a collection will perhaps find this way financially more suitable.
So what do you need to burn a kickstart ROM?
- Firstly you will require a programmer, and the widely available MiniProTL866-II Plus is a great choice. Make sure to buy from an official dealer as clones are rife and there’s always the threat that they’ll stop working with a future update to the software.
- You’ll also need some blank EPROMs (Erasable Read Only Memory chips) and the magic search term here is 27C400. That’s the part number for a 512KB chip that perfectly matches the pinout and requirements of the Amiga
- Sadly those two items already cause us a problem, in that the TL866-Plus II doesn’t know what a 27C400 is. But a quick search on ebay for “TL866 27C400 adaptor” or similar shows that there are very affordable adaptor boards, even available as a kit, which convert the pin locations of the chips to work with the programmer
There is one more thing you can buy. EPROMs have a window in the top, as they’re erased by light. Normally when you buy these they’re blank, which is fine, but if you want to blank a previously used one it needs exposing to UV-C light. Your options here are a proper EPROM eraser device, or you can find a number of devices on eBay that are intended for sanitising objects like mobile phones. If you’re buying one of the latter items, make sure it’s UV-C (not the cheaper UV-B torches), and DO NOT LOOK AT IT. It’s incredibly damaging to your eyes, which is why the proper erasing devices have safety lockouts. You can do without an eraser, but you’re likely to burn through (pun intended) EPROMs whilst you experiment and with no way of erasing them, you’re wasting money.
By now we’ve got a programmer, we’ve got some blank chips, and we’ve got the adaptor to connect them together. The next step is to install the software, and to do that simply follow the instructions that came with the programmer. And then it’s time to program our first chip, and for this we’ll use the AmigaOS 3.2 files as an example.
- Connect the programmer and load the software.
- Place the adaptor in and lock the lever, and then place your blank EPROM in and lock that lever too.
- You’ll need to select the closest match in the software, so click on the chip select button and look for AM27C4096. That’s what your adaptor is converting the 27C400 into.
- Now we need to stop the programming software worrying that the chip isn’t exactly what it thinks it is, so untick “Check ID” and “Pin Detect” options.
- Now open the ROM file. In the case of AmigaOS 3.2, go into the ROM folder and find the right machine (eg A500, A1200, A4000 etc) and use the BIN file. Remember that 32 bit machines need two, a High and a Low so it’s a good idea to write in pencil on the top of the EPROM which one it is you’re programming, if your memory is as bad as mine because otherwise you’ll end up with two written ROMs and no idea which is which…
- The programming software will show the first few lines of the contents, and it’ll look like scrambled English. That’s good! If you’re using a BIN file and it loads and is perfectly readable English (such as copyright messages), that means it needs “byte swapping” – see below.
- If you wish, you can verify your ROM is blank by using the Blank Check option first but if you’re happy it’s blank, go ahead and write the file by using the Program option. It’ll take a few minutes, and verify afterwards.
- Swap the chip, load the second file and do this all again form step 5 if you’re working with two ROMs for a 32 bit machine.
Now you can install the ROMs and test it. This is important – many machines have a 42 pin socket but only 40 pins on the ROM. There is an arrow on the mainboard showing which pins to leave empty, which is pins 1 and 42 (so the ROM sits in 2 to 41). If you ignore the arrow you will cause instant damage to at the very least the ROM! For A500, 600 and 2000 there’s only one socket so just line it up correctly, make sure the notch is at the right end and you should be good to go. For A1200 and A4000, you need to get the two ROMs the right way around
- A1200: U6A is “High” and closest to the front of the machine. U6B is “Low” and towards the rear.
- A4000: U175 is “High” and closest to the CPU slot, U176 is “Low” and closest to the daughterboard.
Hopefully now it’s all working and you have a working Amiga once more. I always like to disconnect any hard drives to force the Kickstart “Insert Disk” screen to appear and check the version. This guide will also work for downgrading ROMs, for example if you want a Kickstart 1.3 chip in an A600 to play older games with a ROM switcher you can burn one in the same way (after legally obtaining it). Also the excellent DiagROM from John Hertell is worth its weight in gold and fully accessible to you now you can program EPROMs.
Things don’t always go to plan, so don’t worry. The most important thing is to always make sure you put ROMs in the machine the right way around, and observe the arrow. Anything else is easily fixed!
- Make sure your EPROMS are blank. Use the Blank Check function to do this (noting that “blank” means FFFF across the whole chip, not zeroes as you may expect to see in the programmer data)
- Make sure they’re real! If you’re getting errors about running out of space or unable to write, be aware that some eBay sellers will remark chips. Try a little acetone and wipe off the markings – although you’ll also find 27C400s that have been remarked as the same chip just to make them look new.
- If you just get a blank screen, it’s possible your ROMs weren’t prepared correctly. The Amiga expects “byte swapped” images; this isn’t a problem for the AmigaOS 3.2 images which are already prepared, but worth knowing if you branch out into writing other files. You will need some other software to byte swap the images, which is out of scope for this guide.
Have you saved money? Probably not – most eBay ROM burning services are about £10-£12 for them to supply and burn an EPROM if you send them proof of ownership or the files. But once you’ve done a few, you may find it financially viable; blank EPROMs are around £2.50 if you’re prepared to wait for the slow boat. Have you learned something new? Totally!
For further reading, you can now start to research how to build your own custom ROMs with new versions of libraries or other customisations in.