Re: cbm 8032 motherboard + 4164

I guess technically 'reversible' means being able to put things back *exactly* the way they were, especially without any soldering, so cutting and restoring traces, adding and removing sockets etc. would not qualify as 'reversible'.

I've often wondered why it's standard practice to install a socket when replacing a single bad chip; presumably the odds of the same chip failing again are slim, and it certainly is a glaring 'modification'.

But in this context it sort of makes sense, since it makes it easier to reverse the mods by putting back the 4116s (if anyone really wanted to).

IMO what really matters is documenting any changes and keeping those docs with the system, especially if they deviate from the official schematic, and especially when they involve changing board voltages and (unnecessarily?) remove functionality such as cassette operation.

m

----- Original Message ----- 
From: <silverdr@wfmh.org.pl>
To: <cbm-hackers@musoftware.de>
Sent: Friday, October 07, 2016 4:12 AM
Subject: Re: cbm 8032 motherboard + 4164



> On 2016-10-07, at 00:39, Mike Stein <mhs.stein@gmail.com> wrote:
> 
> What would make something non-reversible?

MHO of what is reversible and what is non-reversible in this context goes something along the lines of: if you want to install a switch and you have to go even an extra mile to install it in the existing hole/opening that's reversible. If you cut or drill a new hole to install the switch that's non-reversible. Even if we all know that the hole can be plumbed. Similar applies to PCBs. When I design for example my ROM adapters, I make them so that one removes the ROM chips and plugs the adapter into the very same sockets. No trace-cutting, no fly-wires, etc. Changes are reversible [*]. Whenever you want to return to original state, you just pull the adapter out and put the chips back in. Obviously cut traces can be solder-connected back to function but in the context I'd call the modification/damage irreversible - it won't be the same as before when you solder it back together. And I don't even talk about things like drilling/cutting the boards, breaking it into pieces in order to fit into another casings, etc. Those are obviously irreversible in the context, even if one can theoretically try to reassemble things in the original case later on.

-- 
SD!

* - provided sockets were originally there. If not, installing sockets in a clean way, although "irreversible" in the context is still acceptable ;-)


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