Recent content by croissantking

Sounds about right to me (except that 81,920 KB is 80 MB). The concept is a bit like the knock-off flash disks that report their size as 1TB (or whatever) but only have e.g. 8GB of real storage and any accesses past 8GB loop back on themselves leading to data loss.

This has been seen on the forums previously here - @Snial explained in their response below that if you install more than 64MB the RAM will overlap leading to system instability.

Looking forward to seeing how you go with the 840AV. When I get back from holiday I’ll pick up on my PSU rebuild, quite excited to see how that turns out.

✌️ (y)

Very nice to see that chip being so proudly resurrected. And that is rather serendipitous regarding fitment! BTW, I see that the decoupling cap at C7 is missing - I would suggest replacing that. I fitted 100nf passives on the backside so you’ll need something like a 100uf cap on the top.

Yes, if so it can safely be removed temporarily for testing. If it is shorted out it will prevent boot.

Protection diode. Yes, it's a common failure point.

Not aware of one, feel free to take this on :P

That’s a new one. Just before you go any further, can you check all the pins are straight and clean on the interconnect socket? Unfortunately there are no schematics for this model to be found on the internet.

Get on with it already :p

I'd recap both board before you do any further troubleshooting, paying particular attention to the startup circuit on the dead board. I'd start with the one that actually chimes/death chimes though.

I asked ChatGPT to show me how Mac OS X might have looked if it were designed to run in 24-bit addressing mode.

That black spot denotes pin 1, doesn't it?

So tying /WE to VCC fixed the issue?

I may have missed this in a previous post, but what was the reason for desoldering the original mask ROM chips?