exxos's Atari, Amiga & retro forum

Evening All,

Just a quick question. I've got a Rev C C070243 with the -20 glue and mmu. I think the mmu has died. Are these compatible with the -38 versions?

Never heard of a -20 glue ?

exxos wrote: 19 Oct 2020 21:49 Never heard of a -20 glue ?

Here ya go. Writing is out 90 degrees

Yes, they are compatible.

exxos wrote: 19 Oct 2020 21:49 Never heard of a -20 glue ?

The first STs has a chipset made by Universal Semiconductors: https://temlib.org/AtariForumWiki/image ... jokker.jpg

@czietz thanks, it did look like they would be but wanted to check.

In case it's really broken, do you mind -- instead of tossing it into the bin -- sending it to me? (I can pay for the postage.) I always wanted to (try to) decap a -20 IC, but they're so rare...

czietz wrote: 19 Oct 2020 21:58 In case it's really broken, do you mind -- instead of tossing it into the bin -- sending it to me? (I can pay for the postage.) I always wanted to (try to) decap a -20 IC, but they're so rare...

If its really broken then no problem, will do as long as you share the results :D might throw in a -20 glue as well.

The -20 GLUE has "short top border" (PAL screen starts higher up on the TV/monitor than on the later revision)

A lot of demos will fail to remove upper border/start fullscreen on those machines.

/Troed

PhilC wrote: 19 Oct 2020 22:21 If its really broken then no problem, will do as long as you share the results :D might throw in a -20 glue as well.

Sure, if it's not broken, please keep it. In that case it can be better used than for decapping.

W.r.t. sharing the results: It depends on what you expect. I cannot take beautiful high-res die photos like ijor did for the Ricoh (-38) chips (https://www.fpgaarcade.com/wp4/wp-conte ... OP-50X.jpg) because the good microscope lacks a camera and my USB microscope lacks the magnification. Still, I would like to find out if these chips are really Universal Semiconductor gate arrays and thus I'm hoping for a logo and/or part number on the die.

EDIT: So my die pictures tend to look like this (non-Atari chip):

Finally got this machine working, although its stuck in mono mode so got to fix that.

Now I know that the early glue and mmu SHOULD be compatible with the -20 versions as we've discussed earlier in this topic BUT after fixing other issues with the ST I finally got the white border with black foreground, ie memory fault.

I swapped out the -38 mmu and glue for the originals and the machine booted up just fine. So it appears there are differences between the old and current version. No idea what yet though.