ASCIIMath creating images

Wednesday, June 8, 2011

Ancient history: my first Amiga mod

Currently, I am in the process of cleaning up my collection of old computers. I came across one of the pieces I'm still quite attached to (since it was my main computer for a considerable while): my Amiga - one of those before they had model numbers (now called the Amiga 1000). One of the reasons it is special to me is because it was the first major surgery I performed on a computer, which furthermore _had_ to work since I didn't have any other computer at that time. The hack? Expand it to have 1 Megabyte of RAM.

The stock A1000 came with only 256k of RAM, and was quite famous at the time for being able to multitask in that limited environment. However, noone ever left it at that. Almost every A1000 has the added 256k expansion in the front slot, for a more usable 512k. From Commodore's perspective, that was as much as once could expand the A1000 without using the external side expansion slot.

However, if you had the guts to do it you could add another 512k inside the A1000 without a PCB.  This involved piggybacking RAM chips on the existing onboard RAM, and hacking RAS, CAS, and address lines to select the chips appropriately. This is what I did - and I have no idea where the instructions came from. A quick search of Aminet and the Fish Disk index didn't find anything. The hack was done in about 1991, if I remember correctly.

This is the inside of the A1000, with the RF shield removed. Nothing special to see except for one extra small green wire attached to the WOM (kickstart) daughterboard.
Underneath the daugtherboard, it's a bit more messy.  Note that I did label all the wires, but instead of heat-shrink tubing I used bits of electrical tape for insulation.
This shows the detail of 2 RAM chips piggybacked onto the original RAM, with a socket.
Now this is truly ugly. Obviously, I had no idea about proper electronic construction back then.  Yes, these are resistors directly soldered to IC pins.
But, 20 years later, it still works! The screen titlebar actually says "896456 free memory'
This is the only repair I have to do. The wire on the daughterboard is close to breaking off. 
How much I have learned since then... But the lesson I learned is not to be afraid of modding hardware!

Thursday, June 2, 2011

A bit of LaTeX code: placing your documents under a CC license

Distributing digital content with a Creative Commons license is usually a simple affair: decide on the license, and follow the instructions on the website to put it all in there; usually a link and a small png file.

But what if your work is a printed dead-tree document?  What is a visually appealing way to indicate your work is "free" (at least in the beer sense)?

Here is a solution at least if you use LaTeX to typeset your documents.  This was started by my supervisor, Prof. Peter Kabal, and I completed it by adding all the standard CC licenses and cleaning the LaTeX code a little.  The documentation of the package is in pdf format here.  The icons are all svg converted to eps and pdf, so nicely resolution independent.

The package could use some work to make work properly with odd paper sizes.  Email me (or comment below) if that ends up being necessary.