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SiriusHardware · 3rd Feb 2019, 12:34 pm

My two ZX81s, one of them the above mentioned Dktronics-housed one, the other my original machine in its original housing, are both expanded to 16K onboard memory using 62256 SRAMS.

One half of the 32K chip is 'wasted' due to the simplicity of the mod, but there is no practical reason to need more than 16K on a ZX81, as no commercially made software ever expected to find more than that.

It has the great advantage of making the machine rock stable - no more ram pack wobble - and restores the undeniable good looks of the basic machine while making it genuinely usable.

I'm very surprised to learn about the primitive memory arrangements on the Ti-99. I suppose putting the RAM in the cartridges kept the base machine (relatively) cheap and raised the price of the cartridges, which obviously the company hoped you would buy a few of once you had committed yourself by buying the machine.

Didn't they ever produce a simple 'extra RAM' cartridge?

3rd Feb 2019, 12:34 pm	#9
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,577	Re: Texas Ti99/4a out of hibernation. My two ZX81s, one of them the above mentioned Dktronics-housed one, the other my original machine in its original housing, are both expanded to 16K onboard memory using 62256 SRAMS. One half of the 32K chip is 'wasted' due to the simplicity of the mod, but there is no practical reason to need more than 16K on a ZX81, as no commercially made software ever expected to find more than that. It has the great advantage of making the machine rock stable - no more ram pack wobble - and restores the undeniable good looks of the basic machine while making it genuinely usable. I'm very surprised to learn about the primitive memory arrangements on the Ti-99. I suppose putting the RAM in the cartridges kept the base machine (relatively) cheap and raised the price of the cartridges, which obviously the company hoped you would buy a few of once you had committed yourself by buying the machine. Didn't they ever produce a simple 'extra RAM' cartridge?