ZX81X2.ROM - and the big bang

[Skeet]

Wow, that Big Bang ROM is fast
The dual ROM works a treat.
Thanks Moggy and Mark.

[1024MAK]

The dual ROM works a treat.

Good to know you got it working. Please post a photo (or it never happened )

Mark

[Moggy]

Not only fast but an instant CLS after using SCROLL with none of the usual visual mess associated with SCROLL and no sudden flicker when using PAUSE are a couple of nice points also, alongside improved maths functions.

Nice to see you're up and running.

[Skeet]

The dual ROM works a treat.

Good to know you got it working. Please post a photo (or it never happened )

Mark

Here you go...

With hindsight, I should have put the switch on the top clamshell to make opening and servicing the ZX81 easier and probably put tidier wiring on the solder side of the board, but this is how we learn.
I did have the foresight to not put the switch on the back which would have fouled the zxpand.

One thing I have noticed is that Against The Elements does not display properly with the Big Bang ROM.
See photos

First is with Big Bang ROM and second is with Sinclair 649 standard ROM.
I'm sure there are other programs that have issues as well.
Great to be able to switch ROMs!

[1024MAK]

Anything that uses the ROM data as part of the graphics (so called pseudo hi-res) will be affected by using a different ROM to that uses by the game developers.

See also a description of pseudo hi-res here.

Mark

[Skeet]

That's really interesting. I wondered how Hi Res was possible on a ZX81.