May 03

migrated website to a new host

Over the last week, I migrated this blog to a new hosting provider. GoDaddy was such a pig and the site just ran like molasses when hosted by them. I couldn’t be happier with the switch that I’ve made, but I could very well have broke something that I haven’t realized yet. If there were resources that you were using but are no longer available, please leave a comment, and I’ll fix them up.



Apr 25

Reading Amiga Kickstart ROMs with a TL866A reader

I recently bought a TL866A from ebay with a bunch of adapters for a little under $100 shipped. Seems like a decent programmer except for the fact that it doesn’t support the 27C200/27C400 mask ROMs that hold Kickstart. Some alternatives floating around seemed to indicate that the 27C240 was pretty close, but the pinout was different.

I created an adapter to convert the pinouts.

The parts I used were:

While I love Emulation Technology’s stuff, their shit is never in-stock and it’s always so damn expensive. They make a $93 adapter for just this purpose, and thankfully provide the pinout. I downloaded the datasheets for the two ROM chips, and came up with exactly what they did, so I used theirs as the source for the pinout.(PDF linked datasheet). Local Pinout if their link goes down.

Here’s the finished result. Sorry about the wonky colors. Damn cellphones cameras are too convenient! Lots of patience was required to wire-wrap this. (80) connections is no joke!



In Minipro, the TL866A programmer software, I selected “INTEL 27C240″ and this seemed to work, although “Check ID” feature didn’t work, because the chip is identifying itself as something different.



I still want to compare my read with some other files, and check that it worked 100%, but the initial results look fine to me!

A couple things to note:

  • I’m not focusing on whether I can BURN 27C200/400’s yet, I just wanted to read them. I’d THINK this would work, but this would need verified before I’d try it.
  • There is a reverse problem that would require a different solution, and that is using newer/alternative roms IN THE AMIGA ROM SOCKET. Remember, this adapts the amiga rom chip to be readable in the programmer. Nothing more!!

Update: I verified my ROM read 100% correct by comparing the CRC32 checksum to one on the Cloanto ROMS page found here.

Apr 18

Update to Rigol CSV to OLS file conversion post

A couple years ago I posted some information on how to convert a Rigol CSV to an OLS File.

I recently got a request for some more information.

So let’s look at the two files

First twenty lines of the Rigol CSV


First twenty lines of the OLS ouput file

;Rate: 100000000
;channels: 16

So you should be able to visibly see the differences without even looking at the specs

  • Headers are different
  • Rigol has a time stamp as the first column of the CSV (relative to the trigger point)
  • Rigol has comma-separated columns
  • OLS has an “@<samplenumber> at the end

So as you can see, this is a simply moving text around and putting it in the right place. Linux is especially suited to these types of tasks, which is why I chose it over Windows. Right OS for the right job. There’s no perfect OS.

Linux is suited because of it’s excellent set of individual tools that can be chained together using pipes to achieve multiple transformations, all on the same line.

So let’s look at the linux commands and “take it apaaaaaarrrt.” (for you eevblog’ers)

cat NewFile0.csv: Use the NewFile0.csv as the starting point aka input file, let’s look at one line at time.

cut -d , -f 2,3 -s: Use a comma to delineate the columns, and output just columns 2 and 3 (ie the high order byte, and low order byte). The “-s” tells us to not include lines not containing commas.

nawk ‘{print $0″@”FNR}': This gets us the “@” sample number, which is just a constantly increasing number.

tr -d ‘\r’ | tr -d ‘,': Remove the carriage returns, and the still remaining commas produced from the “cut” above.

sed -e “s/ 0/00/” >NewFile0.ols: Replace ‘ 0′ with ’00’ because that’s how OLS needs them. Output the results to a file called .ols. The space before the first zero is very important because it could modify other lines unintentionally!

Example without the “sed” above: “3e 0@662
Example with:”3e00@662

I welcome comments below!



Mar 24

Commodore Amiga Floppy Analyzer


So I’ve toyed with the idea for quite some time about having a tool that was a little more “data” centric for analyzing floppy data. The Amiga Floppy Project Nostalgia client(which was the main Java client for the project) had fairly limited analysis capabilities. It was more ADF-generation tool than anything.

So I spent a couple nights on slapping something together, and this is what it looks like.

It does a bunch of things:

  • The input file is a “Delta T” file which contains time between pulses which are nominally 4us, 6us, and 8us for a LD amiga floppy. This can be generated a bunch of ways.
  • It identifies in range and out range values.
  • It plots all the values in the file on the top chart. Ideally, a really clean floppy read will have three distinct bands. I call these bands clusters. It shouldn’t have many values (outside of the track gap) far from the center line.
  • It locates these starting and ending boundary for each cluster using an adaptive read algorithm which removes things like motor speed variation from being an issue. It automatically adjusts the reading based on the form of the data!
  • It calculates an average for each cluster and displays it as a horizontal red-line on the graph.
  • It finds the magic 0x44894489 sync value and plots it as a green vertical line. Those are the start lines of each sector.
  • The top graph functions as a way to look at all ~50k delta T values and spot the outliers.
  • Next, bottom left, it plots a histogram showing the number of values in each cluster.
  • The bottom center has a text output display that gives cold hard numbers and resulting analysis like standard deviation for each cluster. Lower standard deviation values means a cleaner disk.
  • It decodes MFM using the adaptive cluster boundaries, and then calculates header checksums and datachecksums.
  • It performs (6) different tests on the data and you receive a bright green checkmark if all PASS.
  • If there’s a corrupted sector, then you can drill down into each sector


The above example shows you that Sector 5 is bad, clicking the RED sector number takes you here


Where now your presented with a hex editor, and a copy of the Delta T’s restricted to just that sector.

Now I have very little time so far put into this application, and so it’s not even close to be ready for more-than-me consumption. Things that need to be done are:

  • It handles one track at a time, obviously, it has to handle a whole floppy at a time.
  • There’s no ability fix bad data values.
  • There needs to be an automatic mode where educated guesses can be plugged in, and re attempt the checksums. The problem is that the lousy 32-bit XOR checksum used has a potential false positive rate of 1/32. IE, you can’t brute force it because multiple values will work. (See my post on this topic)

I have some fairly unique methods in mind for fixing this data, but some details still need to be worked out.

Please feel free to comment below about the software.

Mar 24

New 3M, now Desco SCS, antistatic mats arrived today


Before today, I was using a “field anti-static mat” on my HP Logic Analyzer cart. This was the cart that I built from scratch, and I think it did the trick for the most part.

But the more and more I started watching videos, and talking with people, there were much higher quality two-layer mats available. The two layers are the top (dissipative) and the bottom layer (conductive). The wrist straps (through a 10M ohm resistor, for safety) grounds to the conductive layer which is hooked up to an earth ground.

Here’s an image of my new soldering station decked out in 3M blue. I used the 3M 8831 series, and bought them from digi-key, with the datasheet here. I also bought the 2272 and 2224 wrist straps.

These mats are really high quality. Thick, smooth silky surface, great bottom layer. Comes with a dual-port wrist strap system and grounding cable. Note you do have buy the wrist straps separately.

I also bought a mat for my LA cart, but I still have to fit that one.

In the top of the picture, were my new built from scatch shelves that I just installed this weekend. Really getting the man cave outfitted properly, better organized, etc.

Visible on the right is the Rigol DS1102D and the Rigol DP832.

Feb 22

Trying to use mini-box picoPSU-120 to power Amiga but -12v rail is out of ATX compliance

So I purchased a mini-box picoPSU-120 kit which is in essence a very very small power supply that provides multiple regulated voltages. I want to power my Commodore Amiga 500 with the tiny power supply but there’s potentially a big problem with using it out of the box: the -12v rail seems to be out of spec. It’s not being properly regulated to -12v.

I have no problems with the +5v rail or the +12v rail, both measure around +/-1%, or +/-4%, respectively. I haven’t even looked at the +3.3v rail, because the Amiga doesn’t need it.

Their specs are located here.

With their critical specs being outlined here


I wasn’t a math major, but I think this means that the voltages should be between -11.4v and -12.6v. And remember, with load regulation, even without a load, the voltage should be within this range.

But, alas, it’s not:


So I’m getting -13.8v on the -12v rail, which is a solid 15% off target.

Since the PicoPSU is actually a DC->DC converter, it requires 12v input, but I bought their kit, so they are also providing the normal AC to 12v DC conversion with an EDACPOWER ELEC Model EA11203A. The output of this measures +12.49v which is within the the +/- 5% specified on their spec sheet. So this means that the input is ok. And given that it’s unloaded, the voltage sitting high(er) doesn’t concern me at all.

The ATX Specification states that the regulation can be +/- 10% for the -12v rail is allowed, but on the high(low?) side this is still -13.20v. (Section 3.2.1 DC Voltage Regulation (which is a required section) Table 5.)

I double-checked every measurement with another multimeter to ensure that I’m getting decent numbers.

Some others have mentioned that there’s a few things I can do to solve the problem:

  • Use voltage regulation, likely with a 7912, which would handle the negative rail, but I’d have to be sure to get a LDO one. I ordered an LM2990T-12 today.
  • Use two diodes in series for a 1.2v to 1.4v drop. There’s low currents involved on this rail, perhaps 20 or 25ma. So my voltage drop would likely be 1.2v, which would take me from -13.8v to -12.6v. Much more palatable 5% difference
  • Try testing the Amiga at -13.8v by slowing deviating from -12v using my lab bench supply, the Rigol DP832.

In any event, I wish this would have just worked out of the box.

Perhaps it’s me? Perhaps I’m doing something wrong? What do you think?

Feb 08

Powering the Commodore Amiga 500 with the Rigol DP832 supply


So thanks to Mike/amigamech for still having brand new stock of 5-pin A500 power connectors that he could ship quickly.

I used information from for the various pinouts.

I have ordered a picopsu really small power supply to replace the big normal clunky one. I like the idea of using new and still available components where we can.

This is a stock A500 with the only addition being my custom A501 card.

Besides just an excuse to put my DP832 into action, it also gave me the ability to confirm the power draw requirements, and make sure I don’t exceed them with the pico.

The A500, Rock Lobster rev 5, motherboard draws (as you can see in the picture) 20ma on the -12v rail, 22ma on the +12v, and 1.5A on the +5v rail when idle. 8-9 watts for a running machine sounds pretty low to me!

When the floppy runs, which is probably the only other power intensive operation, this 1.55 amps goes up to around 2 amps maximum.

I could try playing some audio(op amps) and doing some serial operations, as they should exercise that -12v rail.

Pretty cool. Also thanks to Dave McGuire for helping me understand negative voltages a little bit. I’m really not used to playing with them, and connecting the positive output of the isolated -12v channel to the ground of the +5v and +12v channels definitely gave me pause. A lack of smoke and a multimeter quickly confirmed that this was fine, if only counter-intuitive for me.

The A500 boots normally and works as it should.