Is it evil to downgrade a Spectrum...?

[Firefox]

@Firefox, there are over 128 free ‘8 bit addressed’ I/O port addresses to play with. More if you use 16 bit address decoding. Or are you intending to memory map something?[mention]Firefox[/mention]

Yeah, I want to map actual memory...

For issue 2 to 4S boards, to disable the "upper" 32k of RAM, take a piece of wire and connect pin 5 on IC23 (a 74LS32) to +5V. (link).

If you wire an SPST on/off switch in series you can enable it or disable it as you see fit. You can even wire in a LED to show the current status.

Ah! By "downgrading", I was meaning to desolder IC23 and replace it with a socket, so I could put the IC back (for a 48k Spectrum) or put a low-profile socket with pull-up (a) resistor(s) soldered across it in instead (for a 16k Spectrum). But that's even easier!

Thanks very much for the tip!

[1024MAK]

Glad I could help.

Do however double, nay, triple check that you have the correct pin on the correct chip, otherwise it could be carnage!

Mark

[beanz]

I don't see an issue with it, the downgrade can always be re-upgraded.

[RMartins]

I had a 16K issue 2 from my childhood and in about 2006 it died as I tried to upgrade it to 48K. e.

It appears that it didn't die.
What happened is that you killed it !

[patters]

I posted on WoS at the time that it would only load from tape for the first few minutes of being on then the ULA would get hot enough to burn your finger on. The upgrade stuff didn't cause that. Then it failed completely.

[RMartins]

I posted on WoS at the time that it would only load from tape for the first few minutes of being on then the ULA would get hot enough to burn your finger on. The upgrade stuff didn't cause that. Then it failed completely.

You didn't need to justify yourself, I was just joking.

But anyway, the process of upgrading it, since it usually requires soldering of at least the extra sockets, might leave you with the uncertainty of having left some tiny bit of solder, somewhere where it shouldn't be.
And I can assure you this can happen without much effort, specially, if you had to de-solder or re-solder any contact, where you used a manual solder pump for example.

That tiny bit of solder can create some sort of short or intermittent short, that can and will probably lead to something being burned by over heating, since a short usually implies a stronger current somewhere.

[1bvl109]

Everyone ...

Well, maybe except those who owned an 81 with a wuhuhuoooOoobly 16k pack.