Sinclair ZX80 / ZX81 / Z88 Forums

Hello
My ZX81 currently has a D4016D 2KB RAM chip and I have a new CY62256NNL chip to upgrade it to 16k Internal RAM.
I know I have to link the following
Pin 1 -> D1
Pin 23 -> D3
Pin 26 -> D5
What I'm a bit unsure about is the link next to the chip, currently LK1 is linked,
do I remove LK1 and move this to LK2 to use the 16k ?

For info - I have already replaced the TV Modulator (Ebay 194240948000) and I've got a replacement keyboard Membrane to install later.

Thanks
Mike

Mikes_LED_Shed wrote: ↑Tue Aug 03, 2021 12:21 am I know I have to link the following
Pin 1 -> D1
Pin 23 -> D3
Pin 26 -> D5

If by D1, D3 and D5 you mean the diodes for the keyboard, yes. Although note that the order that they connect to the chip does not matter.

Mikes_LED_Shed wrote: ↑Tue Aug 03, 2021 12:21 am What I'm a bit unsure about is the link next to the chip, currently LK1 is linked,
do I remove LK1 and move this to LK2 to use the 16k ?

Yes, when LK2 is made, address line A10 is then connected to the chip. If LK1 is made, that machine was only able to access 1K bytes of RAM.

Mark

That's a great help - many thanks