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
16k RAM Chip - Link
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Re: 16k RAM Chip - Link
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 I know I have to link the following
Pin 1 -> D1
Pin 23 -> D3
Pin 26 -> D5
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.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 ?
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
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ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
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Re: 16k RAM Chip - Link
That's a great help - many thanks