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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: spirantho on April 09, 2007, 10:03:22 AM
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Talking about all these bridgeboards in the other threads makes me want to get my uber-rare 486-based A2386 working again. :)
But I need two things:
1) Schematics preferably. Pleeeease! It'd help SO much! You ever tried debugging a three layer PCB without them?
2) RAM chip! I need the 41464AZ08 ZIP RAM chips used for dual-porting! They're like hens teeth.
Can anyone help? Please?
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A friend of mine have a lot (about 30 chips) of zip-shaped RAMs for the A3000.
I think there are the same. PM me if want to contact him.
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Unfortunately they won't be - the 41464AZ08 chips I need are 64Kbx4, so you need two of them to get 64KB. In other words, for one Megabyte you need 32 of them! Hence they're pretty unlikely to ever have been used as a general RAM expansion. If he DOES have any though, I'd be interested, for sure!
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spirantho wrote:
Unfortunately they won't be - the 41464AZ08 chips I need are 64Kbx4, so you need two of them to get 64KB. In other words, for one Megabyte you need 32 of them! Hence they're pretty unlikely to ever have been used as a general RAM expansion. If he DOES have any though, I'd be interested, for sure!
I will check with the fella, them I wanna tell you.
For sure he have that zip RAM chips for the original A3000 mobo.
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Thanks, that'd be appreciated... unfortunately though there are a lot of different RAM chips in identical packages so unless they actually have 41464AZ08 written on them they won't work. But if does have some that'd be wonderful!
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Hello mate,
have you tried RS or farnell ? just a thought.
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Unfortunately these RAM chips are way too obsolete for any modern company. I don't think anyone's used ZIP RAM in about 15 years, let alone page mode 64Kx4 stuff like this!
Thanks for the suggestions, though!
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spirantho wrote:
2) RAM chip! I need the 41464AZ08 ZIP RAM chips used for dual-porting! They're like hens teeth.
Were these used on any of the other BridgeBoards? (x86, x286)
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Nope, just the (expensive) 2386. The 2286 and I think the 2088 both have 64K RAM and use standard jobbies instead of Zip chips. I checked that first as the 2088 boards are dead cheap. :)
Thanks for the suggestion though - any others? :)
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Did you try and Google that part number? You may find some hits. They might not all be able to sell in small quantities, but you might get lucky with one of them.
Try EHL http://www.ehl.com/ (see if Jenny still works there). Those people are great and will try and find anything for you. They used to do small quantities for me too.
Also try;
http://www.lukechips.com/search/default.asp/FullPartNo/41464AZ-08/search/true
Failing either of those options, you may have just have to buy a battery damaged A2386 for parts. It seems like all the ones for sale on ebay lately have had battery damage. The one I bought is pretty severe:-(
How do you know the dual port ram is bad? Were you able to test it? Inquiring minds (mine) wants to know.
Good Luck,
Jeff
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Thanks for those links, I'll check them out.
I know the dual port RAM is bad because all the chips are missing a pin. :) It's a long story but basically I have two bridgeboards and 4 41464AZ08 chips between them. Each needs 8.
For those who don't know what a joy ZIP chips are, the pins on them are VERY brittle, hence why half of mine are missing pins. The other 4 are in my 2386 and I don't want to move them as I might break another pin (it's nearly impossible to mess around with them without nearly damaging one). If I get another 2386 it's quite likely one of the chips will lose a pin and then I'll need another one!
Hence I need 4 more so I can at least try and fix it again (it's just lying there annoying me. Wouldn't be so bad except a) I've never had it working - it got damaged in transit and b) it's so rare! When was the last time you saw a 486SLC Commodore Bridgeboard!?)
It's a kind of long term project. I fear the CBM-specific logic chips soldered to the board may be dead, but I can't be sure unless I have 4 of these wretched chips.
Thinks: MAYBE I can use standard DIL chips instead with a bunch of wires.... interesting idea but it should work...
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I must be missing something, but it's early in the AM:-)
I'm looking at my A2386 right now and it only seems to have (4) of the 41464AZ08 at locations U406-U409
The other zips at locations U302-U317 are bigger MB81C4256A-60PSZ which I believe are 256x4. The dual port 41464AZ08 zips will not work in these locations. You will need at least 8 of these to make 1 A2386 bridgeboard work.
http://cgi.ebay.com/MB81C4256A-60PSZ-MB81C4256A-DRAM-SIP_W0QQitemZ7612696150QQcategoryZ50914QQcmdZViewItem
There was a modified A2386SX bios around years ago that would bump the max recognized ram to 16 megs as I remember and you used a home made Zip to SIMM adapter to make it work. I never went this far, but I may still have the bios file somewhere. Search for "AmiFAST Zip-to-SIMM adapter" and see if that turns up anything.
The 41464AZ08 are soldered in at the left side of the board as you are looking at it.
Good Luck, keep me posted.
Jeff
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Oops, yeah, I meant each board needs _4_. Not 8!
And yes, they're in the same 20-pin ZIP package, but the main RAM and the page mode RAM used by the dual porting are quite different, unfortunately.
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Right, well it's all sorted out now. You'll find it:-D
So, did you do the 486 mod yourself, or is it a clip on accelerator? Care to share the details? I still have the Cyrix clip on upgrade, but I sold my BB years ago. The one I bought to replace it is badly damaged and I haven't tried it yet. I'm still looking for another 2386 to replace the one I sold:-(
Jeff
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Oh, I know where the 41464 chips should be - I was the one who desoldered them. :)
The board is actually a 386 board that was taken by Elite Computer Systems I think it was modified by them to take a 486SLC instead of a 386, and the clock speed was upped to 33MHz.
It's the only board I've ever seen like it.... Problem is I've spent so long with the darn board trying to make it work there's quite a few patch wires all over it now.
I think I was testing it before with the wrong kind of RAM chips, so I need to get hold of these 41464 things so I can test it properly, just in case...!
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spirantho wrote:
The board is actually a 386 board that was taken by Elite Computer Systems ..
That company name rings an old dusty bell in my head, but I can't place them right now.
Were the schematics ever officially released?
Long long ago, before this web thing, we would do these types of discussions on something called 'usenet'. One of the designers of the 386 BB used to be on the comp.sys.amiga.hardware (I believe) group and would sometimes answer questions. Perhaps they could be tracked down now as a lead for the schematics.
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Indeed, Scott Drysdale was on that group. His name is on the bridgeboard itself. Judging by his sig in the only posting I could find:
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formerly mr. bridgeboard @ cbm. soon to be a seaman recruit in the us navy.
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it may be difficult to track him down now!
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spirantho wrote:
Indeed, Scott Drysdale was on that group. His name is on the bridgeboard itself. ...
it may be difficult to track him down now!
Yes, but this may be worth a try, sounds vaguely familiar :)
Mon Aug 08, 2005 11:05 pm
(msg board post deleted)
// scott drysdale // s.drysdale.RemoveThis@verizon.net
// amigas and panheads and guns, oh my!
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Worth a try, but no joy - that address just bounced. Assuming I really did have to remove the "RemoveThis" bit. :)
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spirantho wrote:
Talking about all these bridgeboards in the other threads makes me want to get my uber-rare 486-based A2386 working again. :)
But I need two things:
1) Schematics preferably. Pleeeease! It'd help SO much! You ever tried debugging a three layer PCB without them?
2) RAM chip! I need the 41464AZ08 ZIP RAM chips used for dual-porting! They're like hens teeth.
Can anyone help? Please?
I have a bunch of chips like that but in the wrong package.
Looking at a memory cross reference table, I found that these are the same as the memory chips used in the Commodore 128D for its video ram. However, they were in DIP package format.
Abra electronics also sells these but, once again, in the DIP package.
Jameco also seems to carry them at only 1.69$ each.
See: http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=41574&pa=41574PS
So if you feel comfortable making adapters...
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Looks like that's the way to go then...
I've found some DIL chips on eBay too, they may help.
Thanks again. :)
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Here's where you find ZIP RAM (shameless plug):
http://www.amiga.org/forums/showthread.php?t=53883
As for schematics... I've not found them either :-(
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Oo what a shameless plug, resurrecting my thread from years ago. :)
I did actually find the Zip chips that I needed - and I should point out that you don't have the chips I was looking for - I was looking for the MN41464AZ08 chips which are used for the dual port RAM, not the 514400 chips which you have for the main RAM. But as most people will be looking for normal RAM, not dual port RAM, your plug is allowed. :)
Never did get that bloomin' bridgeboard working. Real shame, given it's one of the very few 486SLC-based A2386SXs....
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Doh! Sorry. I did read that you were trying to repair it but by the time I got done posting stuff I had forgotten it and I simply went off the thread topic -> ZIP+A2386SX = must want a RAM upgrade!
Anyhow, that's too bad it ain't working :-( If you replaced the ZIPs with the correct ones and it didn't work, then what do you think was the problem? Traces? Or battery leak+corrosion? (the dual-ported RAM is kind of far from the battery...)
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Oo what a shameless plug, resurrecting my thread from years ago. :)
Never did get that bloomin' bridgeboard working. Real shame, given it's one of the very few 486SLC-based A2386SXs....
Let's continue the resurrecting, bot the thread and your bloomin' bridgeboard! I hope to play with my bridgeboards after the summer season winds down; I think I have a couple copies of each type. There was even a printed magazine for Bridgeboard users, I may have the complete set - I should probably send them to they guy digitizing all the other Amiga mags.
Any other parts you need for it?
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I got a A2386SX from Ebay a few months back - just out of curiosity because I couldn't afford any of them "back in the days"... Haven't tried it yet as my A3000D is completely disassembled to put a Li-Ion clock battery in (which I did a few weeks ago). Just no time to get it all back together.
If there's anything you want me to check let me know...