Permanent fix for the Amiga 500 rev.5 OOPS bug, and some corroded RAM expansion cards
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- čas přidán 5. 07. 2024
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Socket based adaptor: sites.google.com/one-n.co.uk/...
PCB adaptor: retrozonesite.wordpress.com/2...
EPROM programming adaptor: github.com/mafe72/27c160-tl86...
A500 schematics: archive.org/details/system-sc...
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Thanks for watching! - Věda a technologie
The diag rom didn’t work because there was no sticker over the window 😂😂
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@MrLurchsThings I have watched so many of your videos that this comment played in my head in your voice. 😀
😅
Good job sir!
Thanks for this mate. My diagrom didn't work on my rev 5 (but worked in rev6) and NOW I know why.....
This is a great fix for the rev 5. Sad that Commodore didn't see it necessary to upgrade this older model for their customers to support newer ROMs considering the small fix needed, but I suppose not many customers were using custom/newer ROMs in their system and changing anything risks damage.
Nice, I might follow this at some point. I've kept my rev5 A500 on 1.3 while my A1200 is on latest. But, I've toyed with the idea of upgrading my 500 to latest too. At least now I know how to do the board fix without needing those adapters 👍
It has been a long time but I remember the Kickstart 2.04 upgrade kit came with a wire soldered between two of the pins on the ROM. I recall that for A2000's and newer A500's, the wire was supposed to be cut but left in-place for older A500's. Doing a search, it appears this wire shorted pins 1 and 31.
Sounds correct. On the mask rom Commodore used, I believe pin 31 is not connected inside the chip. So connecting a wire from 1 (where A17 should be) to 31 (where A17 is on the older boards) would correct this issue. Of course this was fixed on newer boards so leaving that wire would have tied A17 to VCC
Good memory as that is exactly right. My upgrade came with the same with a big warning sticker about the wire. I am sure Commodore got a few fried 2.04 ROMs returned from people that didn't read the directions. haha.
@@RacerX- I worked as a technician for a Commodore dealer so I mostly saw those who wanted them installed. I imagine if anybody had any issues then Commodore would have sent them to us but I don't recall any. Of course, that was a long time ago and I just don't remember.
I think that A17 have always same level when accessing KS, so activity on this line happens when KS is not selected, 1.3 is located at 0xFC0000, so if i'm not wrong at 0xF80000 A17 is low, and at 0xFC0000 A17 is high.
From what I remember the resistor packs were needed for stability with some later roms. I have an HE500 with similar damage but its also got a ram fault i think.
regarding your shopping list, the macro lens attachment link shows OOS now, which Immediately brought up about fifty different vendor listings all with the same stock image.With prices radically spread all over the map, 18 to 40 or worse.
But, every single time I picked the lowest priced vendor, there's a more than 50% chance of my missing the, "$34.99 shipping". when the ones two bucks more show free shipping.
Thanks. I've updated the list and replaced a few dead links
You should do a video of how to took this up to hdmi like you did for c64
A while ago i sold 3 512k trap door ram expansions for the Amiga 500 as faulty cause they did not work on my Rev6A A500. I got about $10 each for them and the buyer was happy as they messaged me in delight and told me that the ram expansions work. Some months had passed and i tried another ram expansion that i know works and that too did not get recognized by my A500. I have a 2 meg ram expansion that plugs into the side expansion port and that works fine. What could be causing My Rev6A A500 to not see the trap door Ram expansions??
Could be as simple as bad contacts on the connector, or as complicated as a ram select logic fault
@@TheRetroChannel Thanks for your reply. The contacts look good. I guess if its the latter, i'll just use the ram that connects to the side expansion as my knowledge or skill in trying any hardware repair is limited. Cheers
🍪 Be glad you even get this. I just woke up again, in bed sick. ☣️
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