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New (alt) BIOS for Ultimate 1MB/Incognito

Ultimate 1MB Incognito APT PBI

1329 replies to this topic

#1326 TheMontezuma OFFLINE  

TheMontezuma

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Posted Wed Aug 30, 2017 1:58 AM

prior to their addition, RD4/RD5 resistors were required on the MMU cable itself to protect the CPLD from 5V

 

Do I understand right that the cable connectors from the new Ultimate boards to the MMU socket are different from the old ones?

I thought that they are just 1:1 cables...



#1327 mytekcontrols ONLINE  

mytekcontrols

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Posted Wed Aug 30, 2017 9:42 AM

Do I understand right that the cable connectors from the new Ultimate boards to the MMU socket are different from the old ones?
I thought that they are just 1:1 cables...

Yes the cables are the same as to what signal goes where, but the Candle vs Lotharek U1MB boards are different concerning the RD4 and RD5 connections. With the Candle 'black' board requiring the insertion of 180 ohm resistors inline between the A8 motherboard and the U1MB, whereas the Lotharek board has these resistors built-in.

For those that don't know, the RD4 and RD5 signals tell the system whether an inserted cartridge is either 8k or 16k by simply routing 5vdc to the MMU. And as Jon already stated, without the resistors inline this voltage can damage the CPLD inputs on the U1MB.

- Michael

#1328 Faicuai OFFLINE  

Faicuai

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Posted Wed Aug 30, 2017 10:33 AM

Well I have no idea - I'm pretty sure that I ordered it via lotharek but in any case it looks exactly like this:

IMG_0771.jpg

(verified by popping the lid and taking a look inside.
 

 (...)

 

I need a spare board EXACTLY like this one (initial Candle version that required in-line resistors on connecting ribbon-cable).

 

If anyone reading has an extra one (in perfect working order), please, let me know.

Cheers!



#1329 TheMontezuma OFFLINE  

TheMontezuma

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Posted Wed Aug 30, 2017 10:57 AM

With the Candle 'black' board requiring the insertion of 180 ohm resistors inline between the A8 motherboard and the U1MB

 

Thank you for the explanation. Now I got it. Jon wrote about MMU cable, so I was a little bit confused.

I remember that the cart could damage Candle's Ultimate boards, so Candle has eventually described in the installation manual additional change with 2 resisitors on the mainboard.



#1330 flashjazzcat ONLINE  

flashjazzcat

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Posted Wed Aug 30, 2017 11:21 AM

I used to put the resistors in the cable itself. Xilinx CPLD was supposed to be 5V tolerant, but it was discovered the hard way that it wasn't after all.







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