To make the image for this chip just get your four chosen ROM images, double the size of any 2mbit (256k) images and copy the lower half into the upper half, and then compile them into a single 16mbit image. However if you want to manufacture them yourself or make changes, here’s the Eagle CAD file:Ģx 20 way male pin strip, turned pin typeĢx jumpers, switches, or 2P4T rotary switch (examples)
It should look a bit like this:Īnd it installs like this (photo taken in Rev 6 A2000):Īs with my drive switcher project, I suggest you get the boards made by OHS Park, here’s a handy ordering link: If you want to make life easier when you’re building this, solder the middle pin strip first, then the resistors, socket, other strip and header in that order. So what we have is a 27C160 (16mbit) chip split into four areas by the jumpers toggling high address lines on the chip, presented to the motherboard as a standard 27C400. This is revision 1.1, the 1.0 included a mistake which affected the logical workings of the jumpers.
It won’t work in all machines, if yours can cope with single 20 pin chips then you’ll be fine. So I made a small quad switcher board which anyone can make without having to worry about stock availability. Additionally they only allow you to switch between two ROMs and have quite large physical footprints because for some reason people are really “purist” over Kickstart ROMs, copyright and so on meaning multiple chips or insane solutions like having to download original chips into onboard flash.Īs many reading will know, I’m a member of The Dumping Union, so I don’t much care. There are some quite complex ones which allow you to switch on reset with keyboard strokes, but I found one main problem with these – they’re always out of stock. Hardware options are definitely the way to go. The software ones (for example Relokick) do work, but if you have enough boot time toggles it can start getting unwieldy managing which things are resetting and why – for example booting into 68000 mode on your accelerator card, then booting Relokick to drop to Kickstart 1.3 which involves another reset. Unfortunately a lot of software that hits the hardware directly is affected by which version of Kickstart you’re using, leading to various hardware and software solutions.
The Amiga has had multiple firmware versions over the years, known as “Kickstart”. Amiga (various models) Kickstart switcher Some links and inline-notes, both displayed in red, has been added to this guide after cloning.
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