EEVBlog #438 - Amiga 500 Retro Computer Teardown

[Mike Warren]

That was a nice bit of nostalgia.  I finally chucked my last 2 A500s and one A590 hard drive in the bin about 6 months ago.

[AlfBaz]

Here in australia Keno was run on an amiga for years.
Commodore stuffed up by not monopolising on there CD32 console. I think it was only a year or two after its release that sony released the play station and pretty much took over the world...

I remember seeing the CD32 demoing in shops with signs underneath it saying "this is not a video"... The first lifelike photo I ever saw on a PC was a photo of a ladies face on the Amiga 1200, it came on a floppy with a magazine. I ran out and called the entire family in to see this amazing wonder 

[pbendel]

Nice machines.   I noticed the second machine had an expansion card in it with a toggle switch.  Perhaps that was a kickstart ROM?

[gnif]

That is a common LCD fault, the mosfets driving the inverters often fail, and the circut protects itself and shuts down he back lighting when it detects over current. Just replace the drivers and it will work again

[sleemanj]

Nice machines.   I noticed the second machine had an expansion card in it with a toggle switch.  Perhaps that was a kickstart ROM?

The Kickstart ROM is the Commodore branded chip next to the CPU, the "kickswitch" devices plugged into that socket after removing the ROM (either directly or some had an IDC cable), and you plugged two Kickstart ROM chips into that board (your original and the new one).  Some were controlled by a physical switch, and some had a couple of extra flying wires onto a couple of pins of some other chips and was triggered off of key hold at bootup, from memory.


The second machine's expansion board is just a third party RAM expansion (as far as I remember, the trapdoor was only ever used for RAM & RTC expansion), the switch will be simply to enable/disable the ram expansion (back compatibility basically).

[JoannaK]

Nice machines.   I noticed the second machine had an expansion card in it with a toggle switch.  Perhaps that was a kickstart ROM?

The Kickstart ROM is the Commodore branded chip next to the CPU, the "kickswitch" devices plugged into that socket after removing the ROM (either directly or some had an IDC cable), and you plugged two Kickstart ROM chips into that board (your original and the new one).  Some were controlled by a physical switch, and some had a couple of extra flying wires onto a couple of pins of some other chips and was triggered off of key hold at bootup, from memory.


The second machine's expansion board is just a third party RAM expansion (as far as I remember, the trapdoor was only ever used for RAM & RTC expansion), the switch will be simply to enable/disable the ram expansion (back compatibility basically).

Yes.. Some old programs were coded in a (wrong) way that extra memory cause them crash. So to be comptible with lame coding, you had to have switch option. I even added similar switch to my own 512K memory expansion.

And that expansion is smaller cause it uses newer 256k*4bit Dram chips instead those 256k*1 that original Amiga has.

Some things Dave forget to mention ... Amiga was the *first* home computer with build.in multitasking, good colors (and the pcm sound). Comparable quality Macs and Pc-clones were years away.

It retrorespect it was kinda sad that Amiga was declared to be *toy* since it had those multimedia-capabilities inbuild.

[Dazza]

Awesome blast from the past 

I used to be Technical Editor of Amiga Computing magazine, a UK publication, back in the day and we were always tearing down new kit when it arrived for review. Loved it.

Dave's tear-down has now given me the urge to dig out my old Amiga A1200 and my two Atari 800's. The A1200 is in good working order but one of the Atari's doesn't power up and the other has a problem with one of the ports. Might try my hand at scavenging parts from one to get the other up and running.

Thanks Dave

[iva]

The expansion port on the left was used mainly for Hard Drives, CD-Rom Drives (somewhat later), and most amazingly what were called Bridgecards ("Sidecar") basically what was needed to turn your Amiga into a cross-breed of an MS-DOS running PC "inside" an Amiga, really whizzy bit of kit not too far removed in idea from VMWare and modern virtualisation/emulation, except mostly done in hardware.

Hmm, I think that *mainly* it was to used to plug-in cards like the ActionReplay to hack/crack games at will, I had an Mk.I and an Mk.III 

http://amiga.resource.cx/exp/actionreplay

PS I registered and presented myself 3 years ago and it took the Amiga teardown to give me the will to post a second time, ah the power of those memories!

[JoeMuc2013]

Hi Folks,

thanks Dave, that brought back nice memories indeed.
The expansion port could also be used to turn the A500 into something similar to an A2000. Look what this beast can do: http://www.amiga-hardware.com/showhardware.cgi?HARDID=1369. That put an end to the A500's portability but who cares? It was pretty cool and maximum geek Plus, A2000 hardware was often much cheaper than the A500 equivalent because manufacturers needed to add a case and a power supply for most A500 extensions.
The RAM expansion bus could also be used for different purposes than just expanding the RAM and adding a battery backed up clock. There were some PC emulator boards for it, too: http://www.amiga-hardware.com/showhardware.cgi?HARDID=334
The creativity these days was just amazing...

Thanks again, keep up the good work!

[RichardSim]

From the video @ ~38:45:

John W. Ratcliff, wonder what he's doing these days... if anybody knows, leave a comment

He's STILL at it. No longer (currently) directly working on games, but at NVIDIA on some of their third party libraries for games. He's pretty much legendary.

[DimBulb]

Thanks Dave for the great trip down memory lane. I spent a fortune (it seemed) on Amiga's back in the late 80's. Multi tasking. What a hoot.

[AxelDominatoR]

My first computer! Nostalgy 

I had an A500 with RAM expansion (1MB) and an A590 external hard drive: 20 MEGAbytes! 

If things went differently, Amiga could still be here today. It was an awesome machine under every aspect.

I still have all my disk images here on my pc with UAE! 

[KeithBrown]

Thanks, Dave. I'm an Amiga fan, I still have 4 of them...I actually use an A3000 to control my IR reflow toaster oven!
The  Rock Lobster references have caused me to have the tune running through my head since I saw your video!
So for all the younger listeners, here it is:
(purported to be the official music video, but the quality is poor)
And a fantastic electro-mechanical rendition at
So now we all can share the brain sludge!

[Thermal Runaway]

Commodore actually purchased MOS Technology, hence why lots of the chips in the Amiga were made by them.  Commodore basically had their very own chip FAB, which as you can imagine was a major advantage for them at the time!

Some people might recognise the name Chuck Peddle? Cool name I know.  This guy worked at MOS Technology and then, after the Commodore buy-out, he became a prominent figure in Commodore computers.  I think he mainly did the PET stuff though - I don't think he was still around by the Amiga era.

BH.

[Thermal Runaway]

Inspired by Dave's successful power-on and boot of a 25 year old Amiga 500, I decided to pull my old beauty down from the attic and give her a try as well.  Unfortunately my attempts were met with a blinking power LED and cycling resets.  Removing the cover revealed the obvious culprit:



And...



Also, bizarrely, the battery fuelled corrosion seems to have reached all the way over to FAT AGNUS!



Time to get the toothbrush out!

...an old toothbrush, that is 

[John Larsen]

Inspired by Dave's successful power-on and boot of a 25 year old Amiga 500, I decided to pull my old beauty down from the attic and give her a try as well.  Unfortunately my attempts were met with a blinking power LED and cycling resets.  Removing the cover revealed the obvious culprit:

Did you managed to recover it?

[amigo]

Suffice to say I was a big Amiga fan (I still think it was way ahead of its time) and this did bring a tear to my eye. Not to mention I yelled at Dave (across the screen) a few time while watching the video. 

<----- Just look at my handle, long ago my (at the time) coworkers gave this nickname to me because I used to bring my Amiga to work, and it stuck all these years...

Thanks for the video, Dave.

[Markybhoy]

A recent issue of Retro Gamer Magazine was dedicated to the A500

[gnif]

For those that want a pretty accurate Amiga workbench experience, see http://www.chiptune.com/, this site is amazing and a very accurate clone.

[AlfBaz]

For those that want a pretty accurate Amiga workbench experience, see http://www.chiptune.com/, this site is amazing and a very accurate clone.

[sleemanj]

For those that want a pretty accurate Amiga workbench experience, see http://www.chiptune.com/, this site is amazing and a very accurate clone.

Boy that brings back some memories.  WB1.3 was amazing back then.  I remember the first time I used it, and when I discovered that I was able to multitask!  On a system that booted from a single floppy disk.  It was, stunning.

Funny thing is, using that chiptune demo, the memories are so strong, I swear I can actually smell that first time I setup an Amiga 500 and turned it on (after I had just sold a huge collection of C64 stuff to buy the second hand A500).

[bitwelder]

For those that want a pretty accurate Amiga workbench experience, see http://www.chiptune.com/, this site is amazing and a very accurate clone.

Now I know how my next personal website will look like!   

[Thermal Runaway]

Did you managed to recover it?

Hi John - I'm still working on her.  I tried to clean up the PLCC socket but the electrolyte has actually damaged the contacts of the pins and my attempts to clean it up with a fibre-tipped pen have failed.  No matter how much I rub it down the metal itself seems to have been compromised.

I have ordered a replacement PLCC socket, two 74244 logic ICs, a second-hand FAT AGNUS and two diodes.  I have removed the damaged components and cleaned the board up with some vinegar (I was going to use isopropyl but apparently you need to use an acidic chemical to neutralise the electrolyte) and my next job is to fit the replacement components.

If she's still dead after that I'm out of ideas.  Having removed the affected components I can see the full extent of the leakage and it's quite serious - it's got underneath the solder-resist and spread like a cancer across the PCB.

Wish me luck! 

[AlfBaz]

For those that want a pretty accurate Amiga workbench experience, see http://www.chiptune.com/, this site is amazing and a very accurate clone.

Argh the link was broken because of the comma... and got 404 not found, thought you were trying to be funny with the current amiga WB experience

[NVX]

The picture on the "Sam's Workbench Disk!" screen is Asterix and Obelix from the comic Asterix!

Someone's definitely had some fun customising that one.