16K RAM Pack photos - please add yours

Discussions about Sinclair ZX80 and ZX81 Hardware
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1024MAK
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Re: 16K RAM Pack photos - please add yours

Post by 1024MAK »

The buzzer will be driven off one of the other chips. But the EPROM may contain the code to drive it.

If you know the I/O port address, or the memory address (whichever applies) for the buzzer, a machine code program running in RAM should be able to produce sound from it.

This assumes that it was the intention that the buzzer would be driven by software.

When looking at the photos yesterday, I was wondering why a 16k byte RAM extension needed a 74LS74 (dual D-type pos.-edge-triggered flip-flops) chip. As these are not normally required. But one half could provide part of the circuitry for a one bit output interface, suitable for a buzzer…

I’ve not studied the PCB tracks, so normal Del Boy exclusions apply…
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amauget
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Sinclair 16 Ko RAM pack issue 3 with WRX Mod

Post by amauget »

Here is my Sinclair 16 Ko RAM pack issue 3 with WRX Mod (and a lot of bodge wires on solder side :roll:). It works great !
Sinclair 16 Ko issue 3 - component side.jpg
Sinclair 16 Ko issue 3 - mod zoom with traces cuts.jpg
Sinclair 16 Ko issue 3 - solder side.jpg
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msknight
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Re: 16K RAM Pack photos - please add yours

Post by msknight »

Issue 1 Sinclair 16k
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redgatemodels
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Re: 16K RAM Pack photos - please add yours

Post by redgatemodels »

Lardo Boffin wrote: Wed Oct 23, 2019 6:13 pm I have just got hold of a dead JRS RAM pack so here are some photos of the internals.
Looks like the one I got to replace a lost childhood one is a JRS then. Kinda rings a bell that name ....

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