Sorry, Stupid question time

Discussions about Sinclair ZX80 and ZX81 Hardware
Post Reply
Whopper
Posts: 6
Joined: Mon Jan 22, 2018 8:38 pm

Sorry, Stupid question time

Post by Whopper » Mon Jan 22, 2018 10:38 pm

Hi All,

I've just been watching a youtube video https://www.youtube.com/watch?v=14eL_oWhhXo about using a 32KB * 8bit SRAM chip to get an internal 16KB of memory.

Looking at the datasheets for the 58256 and 62256 together with the ZX81 schematic I wondered if it was possible to also raise PIN2 of the memory chip and connect that to the A12 line from the Z80, as the other four address pins have been raised in the video.

Might this work? Or am I particularly stupid this evening.

Whopper
You woke me for THAT!!!

User avatar
1024MAK
Posts: 1862
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Sorry, Stupid question time

Post by 1024MAK » Tue Jan 23, 2018 3:21 pm

No question is stupid.

I don't have time at the moment to watch the video you linked to.
But there are a number different methods of upgrading a ZX81/TS1000 to having 16k bytes of RAM using a 8bit x 32k byte SRAM chip. Search this forum and you will find various threads about this.

To use all of the RAM in such a chip requires a special circuit, this is because of how the display system in these computers work.

There are details of using all 32k bytes on this site.

Mark

Whopper
Posts: 6
Joined: Mon Jan 22, 2018 8:38 pm

Re: Sorry, Stupid question time

Post by Whopper » Mon Jan 29, 2018 6:28 pm

Thanks Mark.

Now I know what my next project is going to be. :D

Whopper
You woke me for THAT!!!

Post Reply