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Old 06-29-2011, 11:55 PM   #1
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Default Swapping 1.2 with 1.3 Kickstart ROM on A500

Hello all,

How hard is it? I just got 4 A500s (one of them in great condition, but with 1.2 and the rest in really bad shape, but working and on Kickstart 1.3)

I am tempted to open one of those bad shaped ones (well I already did!) and remove its 1.3 Kickstart ROM and replace it with my good A500's 1.2.

The thing is, I am not sure which chip is the real kickstart on A500. do you have a picture of motherboard which clearly shows it?

Also, for some reason the metal shield on the one that I removed its cover got bent and I don't think that I ever be able to replace it back. I am afraid that I will be doing the same with my good A500, when I am removing the cover and its metallic shield. Do I really needs this shield, if I am keeping my A500 at room-temperature?

Oh, and is 1.3 THE most compatible Kickstart, or should I stay with my 1.2 on my A500?

Thanks a million again!

UPDATE 1: OK I found this image. Which one is the Kickstart ROM chip?
http://www.freemansgarage.com/stuff/P1010006.JPG
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Last edited by CodeHunter; 06-30-2011 at 12:25 AM..
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Old 06-30-2011, 12:24 AM   #2
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by CodeHunter View Post
Hello all,

How hard is it?
It's the easiest upgrade you can imagine on the inside of a computer. Take a small flat bladed screw driver and carefully pry the chip out of its socket. Don't lift one side of the chip out of its socket all at once or you might break some of the pins, but alternate sides and lift it bit by bit. The code word is 'careful'.

When you removed the old chip, carefully align the pins of the new chip on the socket and push it in. Mind the orientation of the new chip as it needs to be the same as the old one. Don't turn it around or you might damage it!

Quote:
The thing is, I am not sure which chip is the real kickstart on A500. do you have a picture of motherboard which clearly shows it?
The most important chip sockets on the A500's motherboard have their function written on the motherboard. Look for the socket named 'ROM'. That's the one you need.

Quote:
Do I really needs this shield, if I am keeping my A500 at room-temperature?
No.

Quote:
Oh, and is 1.3 THE most compatible Kickstart, or should I stay with my 1.2 on my A500?
If you're looking for games, 1.3 is by far THE most compatible Kickstart.
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Old 06-30-2011, 12:52 AM   #3
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Yes, mostly for games. So how come this guys swears by 1.2 being the MOST compatible Kickstart then?

http://eab.abime.net/showthread.php?t=32795
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Old 06-30-2011, 03:04 AM   #4
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

In my opinion 1.2 is THE most compatible one, speaking about games (really old ones, until 1990).
I remember in those times people with "new bought " A500 with 1.3 having problems loading some games.

Moreover, but I should investigate, there maybe some problems/little modification for upgrading old A500 motherboards (rev.5) to KS 1.3 (if I'm not wrong it's just a pin). Same stuff if you want to "downgrade" an A500 with 1.3 to 1.2 (but I'm NOT completely sure - anyway you won't hurt anything if you place the chip correctly; just won't boot).

BY!
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Old 06-30-2011, 06:14 AM   #5
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by ognix View Post
Moreover, but I should investigate, there maybe some problems/little modification for upgrading old A500 motherboards (rev.5) to KS 1.3 (if I'm not wrong it's just a pin).
I think that's only for 2.0 or higher ROMs.
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Old 06-30-2011, 06:23 AM   #6
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by CodeHunter View Post
Hello all,

The thing is, I am not sure which chip is the real kickstart on A500. do you have a picture of motherboard which clearly shows it?
http://amiga.resource.cx/photos/phot...res=hi&lang=en is decent image... left hand side next to the CPU with numbering "315093-01" Don't quote me but I believe -01 is 1.2 ROM and -02 for 1.3 ROM. The swap should be simple enough - I put kick 2 in my 500 without any prior experience and it's working!

Quote:
Originally Posted by CodeHunter View Post
UPDATE 1: OK I found this image. Which one is the Kickstart ROM chip?
http://www.freemansgarage.com/stuff/P1010006.JPG
cant see the chip in that pic but the socket has a ribbon cable coming from it to what I assume is a kickstart switcher.
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Old 06-30-2011, 07:18 AM   #7
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by Jiffy View Post
It's the easiest upgrade you can imagine on the inside of a computer. Take a small flat bladed screw driver and carefully pry the chip out of its socket. Don't lift one side of the chip out of its socket all at once or you might break some of the pins, but alternate sides and lift it bit by bit. The code word is 'careful'.
As an alternative to the screwdriver approach, you might try a cheap IC extractor. To pull the ROM I had bend the extractor out a bit before attaching it as they are normally meant for smaller chips. You still want to carefully rock the chip back and forth out of the socket. But I've found this approach a bit easier than the screwdriver method.

My extractor looks like this http://www.jameco.com/webapp/wcs/sto...10001_16838_-1
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Old 06-30-2011, 07:37 AM   #8
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

There are some games that didn't like 1.3 but they are very old and rare.
IMO 1.3 and a 512k expansion (with a disable switch) is going to give you the best all round compatibility.

Jiffy's answer is spot on for all your other queries.
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Old 06-30-2011, 12:16 PM   #9
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Cool Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by tone007 View Post
I think that's only for 2.0 or higher ROMs.
When buying the 2.04 rom you had to cut the attached (welded) patchcable above a certain revision, else leave it untouched (if I remember well).

Last edited by x303; 06-30-2011 at 12:17 PM.. Reason: mmmm
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Old 06-30-2011, 12:34 PM   #10
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

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Originally Posted by fordp View Post
But I've found this approach a bit easier than the screwdriver method.
I've had the exact opposite experience, that type of extractor pretty much relies on brute force whereas a screwdriver (or small pocketknife) uses easily controlled (and limited) leverage. A few mm on the left, a few mm on the right, repeat maybe once and the chip is out.

..not to confuse that useless extractor with a quality PLCC extractor which you really shouldn't do without in the event you need to extract a PLCC chip.
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Old 06-30-2011, 12:43 PM   #11
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by tone007 View Post
I've had the exact opposite experience, that type of extractor pretty much relies on brute force whereas a screwdriver (or small pocketknife) uses easily controlled (and limited) leverage. A few mm on the left, a few mm on the right, repeat maybe once and the chip is out.

..not to confuse that useless extractor with a quality PLCC extractor which you really shouldn't do without in the event you need to extract a PLCC chip.
Couldn't agree more. And if you ignore what Tone said and try to attack it in the center to pry out the chip, you'll end up boring the blade down which could accidentally cut some traces on the board

The "brute force" extractor I only use on small-ish chips. Something as large as the Kickstart chip and you're asking for trouble as it often slips, screws the pins up worse AND ends up piercing your fingers
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Last edited by save2600; 06-30-2011 at 12:46 PM..
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Old 06-30-2011, 02:45 PM   #12
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

codehunter

kickstart 1.2 is the best kickstart for the A500 and it is the most compatible for games
lot of old games from 1985 to 1988 fails to work on kick 1.3
there is no game that works on kick 1.3 but doesn't works on kick 1.2
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Old 06-30-2011, 03:42 PM   #13
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by LaserBack View Post
codehunter

kickstart 1.2 is the best kickstart for the A500 and it is the most compatible for games
lot of old games from 1985 to 1988 fails to work on kick 1.3
there is no game that works on kick 1.3 but doesn't works on kick 1.2
I wouldn't say a lot. But some for sure. I agree 1.2 is the best for game compatibility and if the OP is not going to ever install a Hard Disk to this A500 he should stick to 1.2 KS 1.3 adds autobooting for HD's.
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Old 06-30-2011, 03:46 PM   #14
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by CodeHunter View Post
Hello all,

How hard is it? I just got 4 A500s (one of them in great condition, but with 1.2 and the rest in really bad shape, but working and on Kickstart 1.3)
It's extremely easy. I would get a $10 IC extractor tool from Radio Shack though. Using a flat head screwdriver is ok but you can damage the PCB and plastic socket with it if not extra careful. The IC extractor allows you to pop it out easily with no damage. But you have to align it just right and pull straight up otherwise you can pull the chip out lop sided and bend some pins, but thats ok as you can straighten then no problem
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Old 06-30-2011, 05:39 PM   #15
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

I have always used a small screw driver without any propblems all you have to do is be careful and not try and get the whole of one side off at the one time.
What about a rom switcher? that way you can have at least 2 roms and with a flick of a switch your ready to go.
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Old 06-30-2011, 06:41 PM   #16
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by CodeHunter View Post
How hard is it? I just got 4 A500s (one of them in great condition, but with 1.2 and the rest in really bad shape, but working and on Kickstart 1.3)
http://www.freemansgarage.com/stuff/P1010006.JPG
You could just swap the motherboard

The tin cover is not for dissipation of heat from what I recall. I believe its purpose is to block the RF noise the motherboard produces which can interfere with old school TV reception. With digital TV and cable, I doubt running without the RF shield will pose any problems.

I'm not an electrical engineer (I don't even play one on TV) and could be wrong, so if an airplane lands on your house, your wife can't watch Oprah or the FCC shows up at your door...

Last edited by bbond007; 06-30-2011 at 06:48 PM..
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Old 07-06-2011, 04:27 PM   #17
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Arrow Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by tone007 View Post
I think that's only for 2.0 or higher ROMs.
Hello!
I investigated...

At the moment I didn't test what I'm going to say "for real" but the in theory this is what should be done to use K1.2 on 1.3 motherboards (rev.6a/7) or 2.04 motherboards (rev.8 - A500+) and vice versa (KS 1.3/2.04/3.1 on old rev.5 motherboards).

First of all one clarification (implicit above):
- A500 motherboard rev.5 (mounted KS 1.2 - OCS)
- A500 motherboard rev.6a/7 (mounted KS 1.3 - OCS/ECS 1MB Agnus)
- A500+ motherboard rev.8 (mounted KS 2.04 - ECS 2MB Agnus)

These are what I found here in Italy/Europe, in my personal experience (and not only).

By seeing the schematics (ROM related part can be seen below), in the rev.5 motherboards pin 31 of Kickstart ROM 1.2 is A17 (address 17), while on rev.6/7a ones pin 31 is connected to Vcc, while A17 is located on pin 1.
The same applies to rev.8 motherboards if you pay attention that these motherboards were designed with 1MB Kickstart in mind, so the ROM socket is not 40 pin (for "normal" 256kB/512K ROM) but 42 pin.
In fact numeration reported is referred to a 42 pin socket, but if you place the ROM from the 2nd pin (as printed on the motherboard), pin 2 becomes pin 1 of the ROM, so is the same numeration as rev.6/7a motherboards.
Hope I did not create confusion... re-read carefully with image...

So at the end:
- if you want to use KS 1.3/2.04/3.1 on old rev.5 motherboards you have to rewire pin 1 of the ROM to pin 31 of the socket, and put Vcc (5V) on pin 31 of the ROM (maybe some kohm resistor is not a bad idea, to limit current).

- if you want to use KS 1.2 on rev.6a/7/8 motherboards you have to rewire pin 31 of the ROM to pin 1.

Both modifications could be done with some wires and by bending pins (maybe better if you bend pins from a further socket in between) or creating a proper simple PCB (more work, of course).
In the past (I don't know now) Kickstart switchers provided jumpers for this purpose (but I don't know if they were done for working in all motherboard revisions with ALL Kickstarts, specifically 1.2).

Hope I clarified the thing completely.
If there are mistakes or imperfections let me know, but with precise references (eg. schematics).
I'm especially waiting comments from alexh and Cosmos, who are very competent on this arguments, from what I've read in their posts.

BTW, I'm NOT responsible for any damages to your motherboard, ok?!
Bear in mind that for doing this you need to have at least some basic skills of electronics.

Little tech note for novices:
A0-A17 address bus: addresses 2^18 (0-17) locations = 262144 = 256kB
A0-A18 address bus: addresses 2^19 (0-18) locations = 524288 = 512kB
A0-A19 address bus: addresses 2^20 (0-19) locations = 1048576 = 1MB

BY!

P.S. The schematics are available at the end of A500 user manuals (here pics are small, sorry - I don't know how to place bigger images; maybe a better account...)
Attached Images
File Type: jpg A500 ROM rev.5.jpg (12.4 KB, 4 views)
File Type: jpg A500 ROM rev.6a-7.jpg (14.5 KB, 2 views)
File Type: jpg A500 ROM rev.8.jpg (13.0 KB, 3 views)

Last edited by ognix; 07-06-2011 at 04:49 PM.. Reason: Uploaded better images and typo...
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Old 07-06-2011, 04:44 PM   #18
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Thumbs up Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by CodeHunter View Post
Hello all,
I am tempted to open one of those bad shaped ones (well I already did!) and remove its 1.3 Kickstart ROM and replace it with my good A500's 1.2.
Follow my tech advices in the previous post: I think that just swapping KS won't work (depending on motherboard revision).
But nothing bad should happen, just black screen.
Ask for someone techy to help.


Quote:
Originally Posted by CodeHunter View Post
The thing is, I am not sure which chip is the real kickstart on A500. do you have a picture of motherboard which clearly shows it?

UPDATE 1: OK I found this image. Which one is the Kickstart ROM chip?
http://www.freemansgarage.com/stuff/P1010006.JPG
As other people stated, in this Amiga you have a Kickstart switcher: to change Kickstart keep pressed left (or right) mouse button at switch on.

The Kickstart ROM itself is normally located in the left part of the motherboard more or less centrally, right to big microprocessor MC68000 (where the flat cable of switcher starts from, in you picture).

Apparently the motherboard pictured is an old rev.5 (since the number of chips for 512kB of RAM).

Don't worry about the metallic shield: it's "just" for FCC RF noise (you should place some very electrically noisy stuff to get real problems).


Quote:
Originally Posted by CodeHunter View Post
Oh, and is 1.3 THE most compatible Kickstart, or should I stay with my 1.2 on my A500?
KS 1.2 is the way to go if you want to play many pre-1989 games.

BY!

Last edited by ognix; 07-06-2011 at 04:51 PM.. Reason: Add info...
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Old 07-06-2011, 04:56 PM   #19
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Default Re: Swapping 1.2 with 1.3 Kickstart ROM on A500

Quote:
Originally Posted by ognix View Post
So at the end:
- if you want to use KS 1.3/2.04/3.1 on old rev.5 motherboards you have to rewire pin 1 of the ROM to pin 31 of the socket, and put Vcc (5V) on pin 31 of the ROM (maybe some kohm resistor is not a bad idea, to limit current).

- if you want to use KS 1.2 on rev.6a/7/8 motherboards you have to rewire pin 31 of the ROM to pin 1.
Kickstart 1.3 is 256k, the same as kickstart 1.2. So you don't have to do anything special to upgrade. You should also be able to put a kickstart 1.2 chip straight onto a rev 6/7/8 motherboard without doing anything.

The problem was caused by commodore receiving incorrect information when designing the motherboards for 512k rom chips, which meant one of the address lines was wired to the wrong pin. You can fix it either on the motherboard or the rom. The official kickstart chips came with a wire connecting pin 1 to 31.


My revision 5 a500 shipped with kickstart 1.3 and it requires the pin 1 to 31 mod to work with 2.04 or 3.1
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