Analog TV Death toll

Its Analog TV Death Day in Canada and to celebrate here are a few personal observations.

While I sadly don't have access to any sort of statistics, just going to work each day using my bicycle I got to see lots and LOTS of Analog TVs on the curb. NO thanks to the imps at BestShop for turning customers away from the standalone ATSC->composite converters and towards new LCDs instead. "You know your TV will be dead soon" ... My dad couldn't give a rats ass about HD, while of course I do to an extent.

I bet you a hundred bux my Dad's 1988 Sony Triniton will outlast any new Chinese LCDs. Just please don't listen to the imps cause this is what happens when you do:

Ecocentre des Carrières, Montreal

As a Video Game Console turned Arcade PCB collector, I have to say that right now I'm on the lookout for good analog monitors with RGB inputs being thrown away, these really REALLY can't be replaced. You just have to be able to experience a game on the support it was built for and classic arcade PCB's output pure Analog RGB with 15KHz sync. While I have a trusty Commodore 1084 to support this format It ain't immortal so I need backups!

So the other day, going to work this scene really torn my heart apart:

Poor 1702's! They don't even have a TV TUNER! ... no RGB either, but they of course support SVideo (if you split its luma/chroma signals to separate RCA cables), and Composite. Great for any classic console. A Copper Joke ain't worth that much you scavengers!

Collectors, please stash up at least a spare analog monitor and keep it in a cool dry place, cause prices someday might make you regret you didnt.

Playing the revolution/Home Computer Invasion Documentaries in Trouble???

Original Link being gone, it makes me fear the worse.
I REALLY hope the reason isn't because of damn lawyers!

Here are two other sources for the Teasers on the most thrilling documentary series since The machine that Changed the World:








There's never been a computer documentary this well shot EVER, and nearly everyone I respect and admire in the industry took time to get interviewed. I really don't want this to be shelved.

(SAFE) US SMS Japanese Mod in action

Charles MacDonald provided a circuit for me to try
HERE

Good news is that it now works after a few treaks.
Just have to to a proper protoboard version now.

I'll be receiving two different FM Units soon, the original and the "Australian Reproduction"

The reluctant US SMS that didnt want to be japanese

EDIT2: A new solution (much more invovled ) was suggested by Charles MacDonald this will be interresting to try.

EDIT: Nice, I got my answers in that thread. I'll have to backtrack on when did this become a dangerous thing to try, FYIW I used 10k res to short pin 34.

This MOD does not work on my SMS:

I tried everything, including burning a Japanese BIOS which works great here:

While its cute and all (especially with my RGB mod to a Commodore 1084), I still don't get the mark III boot on my Wonderboy 1/2/3 carts when I ground pin 34 on 315-5216.

Another user is getting the exact same prob with this motherboard rev.

Any takes?

Does ... not ... compute...

Added Internal Picture:





Theres a piezo in there... now if I could
make it beep.....

Horrible damage due to the leaking internal soldered 2x1.5v AA batteries (removed)

The Great AdLib Fire ...

(see third capacitor from bottom) ...  I hate that smell.

From wikipedia:

"Self-destruction and thermal runaway

Tantalum capacitors are under some conditions prone to self-destruction by thermal runaway. The capacitor typically consists of a sintered tantalum sponge acting as the anode, a manganese dioxide cathode, and a dielectric layer of tantalum pentoxide created on the tantalum sponge surface by anodizing. The tantalum oxide layer may have weak spots that undergo dielectric breakdown during a voltage spike. The tantalum then comes to direct contact with manganese dioxide and the leakage current causes a local heating; a chemical reaction then produces manganese(III) oxide and regenerates (self-heals) the tantalum oxide layer.
However, if the energy dissipated at the failure point is high enough, a self-sustaining exothermic reaction may occur, similar to the thermite reaction, with tantalum as fuel and manganese dioxide as oxidizer. This can destroy the capacitor and occasionally produces smoke and possibly flame.^[3] To prevent catastrophic thermal runaway failure, auxiliary protective devices (e.g. thermal fuses, circuit breakers) may be used to limit fault currents"


Oh the joy, guess ill have to replace them and retry .. with the windows fully opened... no lets make it OUTSIDE!

Lamer Exterminator, or how a 22 year old malware can still piss you off.

As usual I need to step back for my obligatory back story.

-VIC-20 from 1981 to 1985
-C64 from 1986 to 1994 (even logged onto my University account with it!)
-Various PCs and Mac's from then on.

Didn't see the word Amiga there? Normal, only very rich kids had them where I came from. Only relatively recently did I start to indulge in that world, and what a 'fun' ride this still is. Amiga literate people can stop reading now, or continue and have a laugh at my expense...

Broadening my quest on early digital sound chips, a look at Paula (MOS8364) was inevitable, although as an 8bit DMA sample playback device, it didn't really fit the original intent of chipsounds. (no oscillators, classic samples are copyrighted, etc).

Nevertheless there are a bunch of things I plan to do following my current OCS Amiga research but I'll keep this for a series of future articles...
... So I got a bunch of gear and disks from various places.

1)Top is my ebay.co.uk bought PAL A500, which I recently upgraded and tweaked (more in a future article).
2)Middle is an Original NTSC Amiga (later re dubbed A1000), a loaner from XC3N which wasn't his in the 80's.
3)Bottom one is my most important Amiga and the first one I found in a recycling center for 20$ a few years ago: an NTSC B2000 (rev6.2a) with 1MB of chip and 2MB of 'fast/slow' ram, and a 'A2320 Display Enhancer' VGA card . This was originally a Video Toaster machine but that particular addon was already removed when I acquired it.  The most important feature of that particular Amiga for me is its generous amount of ram, since this allows transferring PC<->AMIGA floppy images transfers much easily (maybe the subject of a THIRD Amiga article)
I of course also have a weird collection of disks, some that have been recently transferred from the net, but most others are from the 'era' itself, including.... various bootlegged copies of Workbench.

Working on a complex platform that you are not familiar with is daunting for many people, but it is much more so when you get this horrible feeling that everything is flaky and unreliable. Machines that reboots randomly, Disk errors which suddenly appear on what were perfectly good disks just the day before. Since I dealt with 80s technology I just figured this was due to its age and condition...

But NO, it was ME .. the LAMER...  being exterminated!

Only this virus was made 22 years ago and it made me lose PRECIOUS RESEARCH TIME THIS YEAR, since I only figured out what was happening the day I downloaded X-Copy because of its advanced disk checking features .. or so I've read... but as I found out it also scans the boot sectors of each disks for known viruses.

This virus is apparently quite famous for Amiga people, it even has its own wikipedia page. In any case, I was quite happy to wipe all infected disks clean and redoing much of my workbench, utilities, and test disks. Yes you can laugh, but I don't recall ever getting a C64 virus in my day, so I laugh back.. boot disks .... Pffft shush...

And ... That A1000 loaner I got a month ago also came with a bunch of surprises of itself:

Yes XC3N, I've quarantined those for you for when you want to get it back.  :) Don't worry, those last ones didn't make me lose any data, I had learned my lesson by then.

Conclusion: I hate script kiddies, present and past.

patience

Oh yes I'm working on new stuff...

No updates for a while, its because I can't disclose my new stuff yet.
Sad because theres LOTS of research in there.

I'm hoping to post a glimpse at NAMM 2011.

New research on the SID ADSR

My previous post on the SID ADSR tables on the SID DIE left a question unanswered about the exact method by which the chip manages to apply the level changes in the envelopes at certain points in its decay/release stages.

Lucky for us, Frank Wolf took upon the challenge, and I'm quite priviledge to be allowed to publish his research on this blog.

So here is his analysis of that problem....

(high res)

6581 Envelope Generator (26.10.2010)
----------------------------------

In the upper part you can see the R-2R ladder; on the left is the MSB (Bit 7) of the 8 Bit counter.

Logarithmic Table
-----------------

Now take a look a the Table part! Here's the table in ASCII Form and reduced to the values on 'B' lines (please note the every second bit of the 8Bit counter is negated, i.e. the signal line is mirrored A<->B!)

B7 |B6 |B5 |B4 |B3 |B2 |B1 |B0  |Fixpoint|Signal line*
0   0   0   0   0   0   0   0     = 0x00    5
0   0   0   0   0   1   1   0     = 0x06    4
0   0   0   0   1   1   1   0     = 0x0E    3
0   0   0   1   1   0   1   0     = 0x1A    2
0   0   1   1   0   1   1   0     = 0x36    1
0   1   0   1   1   1   0   1     = 0x5D    0
1   1   1   1   1   1   1   1     = 0xFF    6

*The numbers of the signal lines have been chosen to match the numbers of the selector bits!

Every possible "Fixpoint" is compared to the 8 bit counter value keeping only one(!) of the seven signal lines "high" in case of equality. To be more exact: The lines are pulled down in case of inequality.

The 5 selector bits for the logarithmic table are generated by feeding each of the the signal lines 0 to 4 into a simple flip-flop to "set" it. Output of the flip-flops is active "low"!) Additionally both adjacent signal lines are also fed into the flip-flip to "reset" it; resulting in a "high" level output.


Example:

Selector bit|
Signal line | "Reset" signal lines
0             1, 6
1             0, 2
2             1, 3
3             2, 4
4             3, 5

Sustain value
-------------

The 4 bits from the sustain value register are connected to:

Sustain bit 0 to Counter bit compare 0 + 4
Sustain bit 1 to Counter bit compare 1 + 5
Sustain bit 2 to Counter bit compare 2 + 6
Sustain bit 3 to Counter bit compare 3 + 7

So they are (as already known and verified through tests) compared like:

0x0 (S) == 0x00 (Cnt)
0x1 (S) == 0x11 (Cnt)
0x2 (S) == 0x22 (Cnt)
.
.
.
0xE (S) == 0xEE (Cnt)
0xF (S) == 0xFF (Cnt)

Plogue chipsounds running on VMachine Hardware

Composite vs RGB (SNES)

VIC-20 (CR)'s bad waveform clipping.

Poor MOS6560, it could so much better outside a VIC-20!

For chipsounds 1.0, I got the help of eslapion from the Denial forum to analyze the RC filter output of the VIC-20. Eslapion got me to learn how to understand the link between the resistors and capacitors and how to extract the exact low pass filter coefficients that was needed to implement in DSP. It simply turns out to be a 1.6Khz one pole low pass filter. (third party confirmation here).

Such a low cutoff makes for one REALLY DULL sounding chip

But that's not the only sound coloration present on the real VIC. There is also quite a bit of clipping going on when all voices play at once. This clipping does add quite a bit of character when there are a combination of more than one pulse voices playing, as well as the noise channel.

Lets look at the phenomenon on a scope:







Quoting Eslapion:

"The specs sheet of the 6560 specifies the audio pin has an output impedance of 1kOhms. This impedance interacts with C9 (0.01uF) to create a 1st order low pass filter of 15.9kHz.

This is followed by R8 (1kOhms) and C10 (0.1uF) which combine to create another 1st order filter of 1.6kHz.

In other words, these two filters combine to provide a 20dB/decade attenuation from 1.6kHz to 16Khz and then 40 dB/decade above that.

Q1 acts as a current multiplier to ensure enough driving power on the final output but, as we can see, R27 acts as a pull down only device and there is no biasing. The output of the 6560, multiplied by Q1 pulls up and R27 pulls down.

Add to that, the fact that the volume control induces a DC offset.

DC offset values for register 36878: (average) (values picked after R8)
0:4.06
1:4.17
2:4.28
3:4.41
4:4.53
5:4.64
6:4.76
7:4.86
8:4.95
9:5.06
10:5.17
11:5.27
12:5.37
13:5.47
14:5.56
15:5.64

This DC offset, on the final output, is cancelled out by C11 which combines with R27 to create a high pass filter of 339Hz with 20dB/decade attenuation. Therefore, when no sound is playing there is no way to tell on the output that a DC level forms on the base input of Q1 as the volume is increased.

If the 6560 is going to pull up in DC when the volume rises then the maximum excursion of a sound wave is limited by a combination of the pull down current (set by R27) as well as the voltage feed which, in this specific case is 0 to 5volts. When the volume goes above a certain level, clipping of the positive side of the wave occurs as the 6560 attempts to pull up above 5V.

This clipping effect is even more intense when playing multiple voices simultaneously as their combined excursion adds to each other.

Obviously, the smallest amount of clipping occurs when the DC offset provides a DC level of 2.5V on the base of Q1. This is achieved when setting the volume level to 8.

Now, looking at the rise and fall time of the signal taken directly at pin 19 of the 6560, we see that the rise time is much greater than the fall time. Considering the effect of Q1, as seen by the 6560, R27 should appear as about 100 times greater.

This asymetrical voltage change is caused by the diode in the base of Q1 which can draw current on voltage rise but not give back any on the falling edge. This causes C9 and C10 to charge slowly as Q1 "steals" current used to charge these capacitors but not restore it when the 6560 discharges them. This assymetrical time constant is less dramatic on the actual output as C10 and C11 are still discharging at the very instant C9 appears to be empty."


Heres an audio capture form the final analog output of the VIC-20 CR:

Clipping sound

So there you have it!

The VIC emulation im working on for 2.0 includes that clipping and filtering and is starting to sound very close to the real thing.... stay tuned

X marks the spot!

People following my twitter might have been wondering what that Canadiana Road Trip stuff was a'boot yesterday. It was about salvaging a pile of 50 arcade boards from certain death.

My Pirate Map pointed to a secret location near Ottawa, Ontario, so went, dug up, and found the treasure!

(yes that's the trunk of MY CAR)

A quick evaluation can be made to about 65 soundchips on these. (some boards do have more than one). I don't know WHEN I'll get time to go through the good, the bad and the awesome. What works and whats useless, but there you go.
Each board is different (except two MS Pacman boards, but i will NOT complain here, lets just hope I can get one running, even it if means cannibalizing the other)

chipsounds 2.0 R&D really REALLY doesn't need more chips at this point....

well there's ... oh hell...

30 Minute JAMMA SuperGun Audio test

I use MAME differently than you I'm pretty sure. You can sort games by name, company, date, but usually I sort entries by 'sound'. For a guy like me, its both salivating and dangerous... for my finances.

There are a few sound chip gems that are only found on obscure PCBs. However, a side effect of the omnipresence of MAME is to somewhat lower the price on used game PCBs on Ebay. Why would you have this 20+ year old board around in a wooden box when you can play the game on your PC or some MAME'ed cabinet?

When you're a sound chip freak its not a question of course. Since I cant put myself to loan a van just to shove an Arcade cabinet into the office (not that it wouldn't be nice to have a Shinobi or Splatterhouse around). It just wouldn't be convenient.

I'm contemplating starting a collection of PCBs, to get new chips, but also just to get a few spares. Recently I acquired a 10$ game from a local Ebay seller, a really crappy Jap quiz game to get an extra YM2413.

Friday after work, bored, Ok should I trash this board and get the chip from it? Or, wait a minute... there must be something to play this thing for cheap! And of course there is ... A SuperGun!

Two minute googling and I found this very well done document on building a home made JAMMA harness. Cool, but i just want to HEAR the intro tune, not to see and play it!

I had about 5 more or less useless PC casings at home, so I looked around for one which had a suitable PSU (read working +5v,-5v +12v). (it allowed me to sort through them at last and thrash two deabeats, ... missus is happy)

15 Minutes soldering and it worked.



That is JUST a test of course, I'll surely hook all that with two joysticks an fake coin slots on the PC case in the future. And of course proper video outs.
Or.. maybe I should go back to sound R&D...

More later

Curves

teh curves.

ZIF socketed C64 for SID chip swap

ZIF (Zero insertion force) sockets are a great way to reduce the wear on chip pins when you need to swap them often, which is as you've guessed  what I need.

A simple 28PIN ZIF socket like this:

Can be used to quickly swap SIDs to run tests.




Video:

Best registration plate ever

Thats sadly not my car, can't have custom plates in Québec.
Oh well.

I'll get you 1771!

A full day spent figuring that chip's sound generation again. Recorded the two separate output pins in a multitude of ways, but there seems to be signal bleed whatever I try (even removing the chip and lifting one of the pins of its socket from the circuit)

This is not your typical PSG.

uPD1771C noise puzzle

LFSR feeding a delta-modulated logarithmic DAC???
Evil 80's reverse engineering protection???
Alien message?