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Old 02 January 2005, 16:41   #1
dirkies
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Question A500 with HD & Kickstart issue

I bought off eBay an AlfaPower Plus 270MB external HD+8MB+ext CDROM with a 1.3/2.04 kickstart switcher (the Utilities Unlimited one) for my old A500.

kickstart switcher info:
http://www.amiga-hardware.com/showha...cgi?HARDID=685

The A500 is a rev5 1.3 OCS machine, with A501 ram expansion, a DF0/DF1 bootswitcher, but nothing else fancy on it, and it was for at least 5 years not switched on, but it did switch on from the first moment

mobo type assembly 312510:
http://www.amiga-hardware.com/downlo...0mb_rev5_2.jpg

harddisk looks fine, spins up etc. No problem with that.

Now the harddisk is already installed with a kickstart 2.04 bootable system, but the problem is now, when using the kickstart switcher the Amiga won't do anything (it switches on but screen remains black and power led won't illuminate).
I doublechecked the connections (see link), and tried various connection options, so that can't be it.

Now if I insert the KS2.04 rom (chip= 390979-01, says 37.175) directly to the mobo, the machine will switch on but screen will turn red, then show some garbled scrolling gfx for 2 seconds and then turn plain red again and nothing else happens. (red=ROM ERROR)

If I just use the 1.3 kickstart (chip= 315093-02), the harddisk will boot but guru immediately probably because it loads 2.04 drivers the rom doesn't understand.
So I can't boot from floppy since the HD will try first and gurus.

So my questions are:

do I need to replace anything else if I insert a KS2.04 rom or should a simple swap be enough? In that case I guess the chip itself is fried or not? May it be this case of soldering a cable between pin 21 & 31 on the chip itself?
see: http://www.l8r.net/technical/t-204rom.shtml

Should I perhaps use a 2.05 chip? A 37.350 cause that is with a fix for A600 HD or has this nothing to do when used in an A500 with HD?

Anyone else has a similar kickstart switcher? If so, how exactly are the chips aligned since the pic in the link is another revision than the one I have. (mine has just the size of 2 KS chips, and the controller chip sits underneath the U2 chip socket) And also how the actual switcher is connected to the mobo, it's a bit confusing to know what is pin1 on the replacement plug since it red dimpled cable (normally indicates pin 1) is aligned with pin 40 of the kickstart chips!? Or is this normal. The KS chips are clearly ok inserted (half moon aligns with what's indicated on PCB)

How can I access the HD in 1.3? (so basically trying to boot from floppy with the HD connected)


Thanks for any info you can share on this

Last edited by dirkies; 02 January 2005 at 17:21.
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Old 02 January 2005, 19:25   #2
Jope
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The Rev5 A500 needs a jumper wire between pin 1 and 31 of the kickstart chip.

The HD will probably also be readable under 1.3, just pop in a workbench disk, open a shell and type info (you'll should also see the HD's icon on the wb screen). However, if the original owner didn't install FFS into the RDB of the hard disk, you will not be able to see the drive automatically in 1.3.

The kickswitcher sits over the Agnus chip, the flat cable runs right (towards the end where the floppy drive is) from the kickstart socket.

I'm not sure if you really need the other wire (from 21 to 31) and the bent up pin 31.. Back in 1993 when I installed 2.04 in a rev 5 machine myself, I just soldered the wire between 1 and 31 and plugged the chip in.
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Old 03 January 2005, 01:08   #3
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thanks Jope, will try that!

So the flat cable runs without being twisted at all to the right, while both kickstart chips are face UP I imagine and their little orientation mark is facing towards the connection ports? (so the red dotted cable on the flat cable is facing the keyboard)?

I hope it will not be black screen again if I reinsert it correctly!
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Old 03 January 2005, 11:56   #4
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Yes.. the chips in the switcher and the socket on the motherboard have the same orientation.

Just make sure that you plug the switcher in the motherboard carefully, mind you don't bend any pins.
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Old 28 March 2005, 16:56   #5
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OK, just revived this thread. Since it never worked with KS2.04, I bought at Vesalia a KS2.05 chip. Now I retried, no luck, my A500 rev5 still shows a red screen at powerup and stops there.
So did the instructions from the webpage mentioned above, bend pin 31 outside of socket, wire from pin 1 to socket 31, and wire from bend pin 31 to pin 21.
Now I no longer get a red screen (phew!) but the dark grey screen, but it doesn't cycle to light grey and then white. (I assume white with OS2.0). Even without mem does same. I can do a reset (a-a-ctrl) but it will return to dark grey. Seems this means the hardware check passed but the software isn't. I'm still using original chipset for all the rest, just the kickstart chip was changed. (not a fat agnus etc)

Anyone else can help me out or give suggestions? Thanks!
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Old 28 March 2005, 17:33   #6
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Try it like this:

- don't bend out anything
- just solder a wire between 1 and 31
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Old 28 March 2005, 18:42   #7
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From installation leaflet:
For rev.5 boards the ROM socket must have pin 1 connected to pin 31. The ROM IC must have pin 21 connected to bent-up pin 31.

That's it - hopefully...
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Old 28 March 2005, 19:46   #8
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well, I tried with all 40 pins socketed as it should, with a wire from pin 1 -> 31
RED screen

put an additional wire from pin 21 to 31
RED screen

bent chip pin 31 so it is not in the socket, both wires still present (= pin1 of chip connected to hole 31 of *socket*, pin 1 still in hole 1, pin 31 not in hole 31, and wire does NOT touch pin 31, so this is the same result, no?)
DARK GREY screen (so no longer a ROM error)

same as previous case, but wire 1 -> 31 removed
BLACK screen
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Old 28 March 2005, 20:06   #9
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and I did retest with a 2.04 : same behaviour as a 2.05 chip

and I did not fry my machine, I retried afterwards with the 1.3 chip and it starts up nicely.

I'm puzzled & desperate!!!
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Old 28 March 2005, 20:50   #10
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Hmm. Sounds so strange. When I installed a 2.04 rom into my rev5 machine, I just added one jump wire to the chip and it started working.

I can't remember the pins any more, it's been 13 years and alas I don't have that motherboard any more either. :-(

Are you sure you're counting the pins right?

This is for a 16 pin chip:
Code:
  _ _
1| U |16
2|   |15
3|   |14
4|   |13
5|   |12
6|   |11
7|   |10
8|___|9
The chip is text side up in the illustration.
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Old 28 March 2005, 21:34   #11
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kickstart is a 40 pin one

pin 1 is top left
pin 21 is top right, no????????? Or is it bottom right?

At that moment I'm wirejumping pin 29 instead of 31 ! Can I try this or am I gonna fry my chip if I try it?

so to recap:
Code:
  _ _
1| U |21
2|   |22
etc

or is it 

  _ _
1| U |40
2|   |39
etc
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Old 28 March 2005, 21:49   #12
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just tried again (pin 31 bent, socket 1-31 connected, pin 21-31 connected) with counting pin 21 from bottom right, but no change, still dark grey screen. Power led now stays on (before it didn't)

tried also just wiring 1 & 31 with all pins inserted (but counting from bottom right upto 31) but still same thing.

???
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Old 29 March 2005, 06:51   #13
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Kickstart pins:

Code:
   _ _
01| U |40
02|   |39
03|   |38
04|   |37
05|   |36
06|   |35
07|   |34
08|   |33
09|   |32
10|   |31
11|   |30
12|   |29
13|   |28
14|   |27
15|   |26
16|   |25
17|   |24
18|   |23
19|   |22
20|___|21
(the pins of all DIP cased chips are numbered in the same way, anti-clockwise)

If I were you, I'd go and test the chip without jumpers in a rev6 machine to see whether it still works.

Unfortunately I don't have a pinout of the chip handy, so I can't say what happened to it (if anything) when you jumpered the wrong pins.
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Old 29 March 2005, 11:34   #14
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I don't have another A500 handy, but I don't think it would fry anything, judging the nature of this rom chip.... maybe I'll have to find a REV6+ A500 on eBay, but that is really the last option...
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Old 29 March 2005, 12:45   #15
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Unless you tie vcc to gnd, it shouldn't.. But at least I don't remember how the pinouts go and the A500 schematics I googled up are so low res that I can't make out the text.

(my A500 manuals are packed up in the attic.. :-P)
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Old 29 March 2005, 21:40   #16
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Don't know if it helps at all but when I upgraded my old 500 I just placed a KS 2.04 chip right into the socket that had the 1.3 KS chip on my Rev 6A 500 and it worked fine. Didn't have any jumpers or wires to play with.
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Old 30 March 2005, 06:41   #17
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I cursed the lucky Rev6 owners too back in my day, but thankfully soldering that jumper wasn't such a big task afterall (I was twelve when I installed 2.04 in my old A500).

Before rev6, there were no 512kB ROMs envisioned yet and the commodore people got wrong info on the location of the uppermost address line (which was unused in the 256kB chips). This was fixed in rev6 onwards.
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