exxos's Atari, Amiga & retro forum

If you can make it then it'd be great to meet you.

stephen_usher wrote: 12 Sep 2021 18:42 If you can make it then it'd be great to meet you.

I'll see what I can do :)

The memory upgrade PCBs have arrived.


The hardest thing I need to do is solder SIOC surface mount SRAM on the other side, which has incredibly fine pins!

stephen_usher wrote: 13 Sep 2021 13:03 The memory upgrade PCBs have arrived.
IMG_2380.jpg
The hardest thing I need to do is solder SIOC surface mount SRAM on the other side, which has incredibly fine pins!

Very nice :)

The board passes its initial electrical and physical tests.

I fitted a connector to an unpopulated board to do a sanity check. It fits correctly, +5V and GND are in the correct places and the machine still boots, which is a bonus. I've not checked any of the data or address lines yet but it's a good start.


I also tried the 8 pin DIN socket but that's not so good news. The pins are FAR larger than the holes I specified. I'm going to have to file the pins down for these boards and modify the footprint design.

Fitted everything except for the GAL and memory and everything seems to be operating correctly.

The address lines are latching, the control lines are doing what seems to be correct and, more importantly, no magic smoke. The machine still boots normally.

GAL programmed and installed.

I'm going to need a bodge wire as the GAL programming software doesn't like a logic high output on pin 19 so I've had to switch to pin 15.

Still, I'm seeing activity on the selection line during the initial RAM test stage of the ROM along with data line activity at the same time.

So, bodge wire and SRAM (eek!) to do tomorrow evening.

This is the scary surface mount device pad...


Still, the board looks OK in general. The noise levels on the traces are fine, so a 4 layer board is not needed.

@stephen_usher That's a similar footprint to all the parallel Flash devices we're using on our products...as/when we can get hold of them!

Our repairs guys can swap the chips off one board & onto another in mere minutes with almost no problems...I'm never likely to get anywhere near their levels of expertise!

Good luck when you attempt to solder that one...and stay off the coffee for a couple of hours beforehand ;)

Hehe. Yeah! It's going to be "fun"!