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inital results on error correction

While I have yet to actually implement the full-scale error correction as I want to, I did some manual tests today. I basically took a track that I was erroring out on, and swapped in 1-bit away values for the bad bytes.  In some cases, it appeared...

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Creating a timeline of events

It’s often useful when trying to understand, debug, or reverse engineer a system to put together a timeline of operation from beginning to end. The result is a series of events where something happens first, then...

Identify PAL inputs and outputs

In order to properly reverse engineer a PAL, you need to correctly identify which pins are inputs, and which pins are outputs. This in some cases is trivial because some of the PAL’s pin functions are fixed...

Understand the system

Of all of the different techniques this one may be the simplest but also the most important. When you’re trying to reverse engineer something, understanding the system is key to unraveling the black box which is...

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On building an A500++

Commodore Amiga 500 Plus In the 1980s, Commodore made a newer version of their very popular Amiga 500, called the Amiga 500 Plus. It added a few things, namely newer versions of Kickstart and Workbench — both 2...

Day 4 of my assembly of A500++ PCB

I finally got my PLCC 84 socket in from Mouser out of stock and installed more EMI caps. Slow going…..made little progress on THIS project this long weekend, but I did make progress on other projects….. This...

how the amiga reads floppies

how the amiga reads floppies

So I’ve forever wondered, at the hardware level, how the amiga reads floppy disks.  I’ve gotten bits and pieces over the years, but I’ve never really understood the bulk of it. So there are four main...

floppy.c’s mfm decoder

floppy.c’s mfm decoder

A couple days ago, whenever I got ahold of floppy.c, I wrote a quickie code stub that utilizes floppySectorMfmDecode from floppy.c of fellow (). Note you must use the mirrors to actually download anything…. This...