ALPHA CPU Extension Board - Yes Another Tower

[Icky]

To continue the testing and development of the STF Remake Exxos and I have been discussing a CPU extension board to go on the STF to help test various things out with the Alpha, such as the IDE DEV board and the SEC 50MHz booster.

The board solders into where the CPU socket would be on the Alpha and then provides the user to either use a 68000 DIL or 68000 PLCC depending on their required use.

It will have a resistor SIL to replace the missing pull-ups for BGACK PULL UP FIX and BR Fix around the 68K. I you want to take those off of the bottom of the board you can just place the SIL on this board to have a bit of neatness.
https://www.exxosforum.co.uk/forum/viewt ... =20#p10198

Image is for size and placement reference of where it will go on the Alpha.

IMG_3829.jpg

[PhilC]

Looksa good idea to me and has persuaded me to fix the video on my STF Remake.

BTW, one of your chips is missing its sticker. ;)

[PhilC]

Just checking but possible adaptor for STEs as well maybe? Could test the IDE on those too if theres any interest?

[exxos]

Just checking but possible adaptor for STEs as well maybe? Could test the IDE on those too if theres any interest?

It could be done.. but with STE's being so unstable to start with, I think its opening a whole new can of worms... Most boards myself and Icky are working on are heading towards only really being used on the remake boards at the moment. The remake board is the only stable board to develop on. Its why I pretty much abandoned upgrades for other machines, as just spending endless time chasing design faults or bugs in the motherboards themselves rather than developing hardware.

[Icky]

Here is the finished versions of the design of the simple expansion for the Alpha to help test other boards on it such as exxos' SEC booster, IDE Dev board etc.

The RN1 SIL is for replacing an Alpha fix as mentioned at the start of this thread and the JP1 is on the CPU clock line so we can easily plug a line in from the 16MHz board exxos has designed.

Screenshot 2019-05-09 at 21.20.39.png

[Icky]

Built one of these up tonight. This is going to need some surgery on the ALPHA board to get up and running.

I put the RPN1 (2K2) in as I will take the patched one off the underside of the ALPHA board.

IMG_3962.jpg

IMG_3963.jpg

[PaulJ]

Let us know how you make out.. :)

[Icky]

Let us know how you make out.. :)

Will do PaulJ. One thing I have noticed is on my ALPHA I had used SIL sockets and DIL sockets for the components around the CPU where this board will go. As we now know these components work I will remove the sockets and drop the components in directly so as to get this board in nicely. Otherwise we will end up with more stacking.

[Icky]

Just finished my 16MHz Mod board plug-in so thought I would now move onto the next phase - fitting the extension board.

Took forever to get the PLCC socket out, it was being a little stubborn. After unsoldering the socket I put in a makeshift socket from SIL's to be able to plug the board in.

IMG_3974.jpg

I noticed I have to bend some of my 16MHz mod headers slightly to get the board in and be able plug the 16MHz etc lines in. Also I have used the RN1 so as to remove the one that was under my board. Cleaned up my board underneath no end. However I noticed I missed out the pull-up on the BG line. Patch for the extension board if using the RN1 is a thin wire from the RN1 to the BG pin as can be seen in the pic below.

IMG_3975.jpg

Now all I need to do is put the 16MHz mod back on and the RAM board and see if this board fires up. Not sure I will get time tonight as its gone midnight.

[PaulJ]

Looken good Icky.. plug the IDE/206 board in and you may win the high-rise contest. :)