Sinclair ZX80 / ZX81 / Z88 Forums

I thought it was an interesting idea that Sincl.air could have made an additional 16K rom for the zx81, especially when 16k roms became cheaper like when they were making the Spectrum etc. I have a feeling this might have been a popular add on for the zx81 and wouldn't have been that hardto do. They...

Some of the boards even have a larger rom socket!
Was this so a 16k rom couldbe added at a later date or something else?

See Below:

https://www.sinclairzxworld.com/downloa ... hp?id=4703

http://gja.space4me.com/zx81/motherboard-closeup.jpg

I think you are right. The original author had a great idea to make a Hunchback style game for the zx81.
It didn't work out that well but it was a great idea.
So we should be thankful for the idea.

The Zx81 should be able to do it really well, after all there was a version for the Dragon 32!

This is a bit of a strange question so I'll try and expain a bit. Could Sinclair have added a 16K Basic Rom to the ZX81? I mean I know they could do almost anything to it in theory but given the existing hardware in the zx81,would there be road blocks to making a 16K Rom work. For instance are thing...

Moggy wrote: ↑Mon Feb 20, 2023 3:12 pm The ZX81 ROM was supposed to have...

DATA

DRAW

PRINT TO

...

PRINT TO sounds really interesting!
Do you know what that command was supposed to do?

PLOT and UNPLOT work as expected except the plot coordinates are 64x48 instead of 256x192. Regards; Greg PS actually the PLOT coords are 64x44 but can be increased to 48 easily with MC. Thanks Greg, So basically it's just printing block graphics with a different coordinate system than Print AT? Kin...

A character can also be 4 pixels. a bit like character 129 to 143 on the ZX Spectrum. PLOT will set the large pixels in a character on the screen. Since the screen is character based you can't plot a pixel at the position of a character unless the character is the graphical character 0 to 7 or 128 ...

I'm familiar with sinclair basic on the zx spectrum but wondered about the zx81 plot/unplot commands. They don't appear to work at the pixel level so I'm wondering how they are different to Print At with the semigraphics/Block Graphics? There isn't even a draw command on the zx81 so what is it all a...

Thanks 1024mak! So a 32k internal zx81 ram upgrade can use all the different hi-res modes? That's great news! The ram upgrade disables the original 1k tho... Could that be moved to the first bank of memory above the 8k rom so it could still be used? The other slightly related thing I've heard people...

I've heard conflicting things about this and wondered if anyone can tell me about hi-re graphics on the 1k zx81. I heard it is because the 1k is static ram and the 16k ram pack uses dynamic ram? What truth is there to this? Is it something the ula is doing? Some people install 32k in the zx81 as sta...