Found these inside a non-working 71B

[MikeSD]

You are right. Never noticed. There is a diff. That top device is the one that is loosish (see comparison below) That is the chip my 32k RAM daisy chain from. if ROM wonder what it is. Maybe another app. It's marked 5180-2918.

I found a schematic. It shows 5 mem chips. Mine has 6. Based on differences, I assumed the 2 I have on right in my pic are ROMs. But now I think 5 are RAM and the top is Rom or an app chip. I'll do a little more checking around. I know I have the IDS on my computer. I'll take another. Maybe the schematic there is different.

NOTE: Wonder if anyone has an original service manual to sell. I have a copy but...

Mine is metal back. I have half dozen non-working ones I need to get around to one of these days.

My IDS only has block diagrams and nonpin-outs. Only names. Guess I have a brief version. Still I think I have enough information to tackle this.

Thanks