16k RAM Chip - Link

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Mikes_LED_Shed
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Joined: Tue Jul 27, 2021 9:32 pm

16k RAM Chip - Link

Post by Mikes_LED_Shed »

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
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1024MAK
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Re: 16k RAM Chip - Link

Post by 1024MAK »

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
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Mikes_LED_Shed
Posts: 3
Joined: Tue Jul 27, 2021 9:32 pm

Re: 16k RAM Chip - Link

Post by Mikes_LED_Shed »

That's a great help - many thanks :D
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