Wait mod + ZXPand+ issues

[Enigmachine]

Hello wizards!

I tried the "why wait" mod on my issue 3 ts-1000 (using the default 2907 transistor) and it worked perfectly fine for long minutes, a sweet 10% speed boost and stable picture. But when using it with my ZXPand+, I would get progressively more RAM corruption whenever I would shift-reset instead of turning it off/on to reboot. At first I thought it might be heat changing the saturation times on my new transistor but since the corruption happens *exactly the same way* every time I reset, I think the explanation might be closer to what SirMorris posted in the "TS 1500 and ZXPand" thread.

Maybe during reset the zxpand has to race with cpu to remap the ROM & RAM and my mod might affect the delicate timings? I don't have the skills or equipment to verify that, but has anyone else experienced this and is rebooting the only solution (other than removing the mod)?

I'm asking this before I try adding a clock doubler mod; that's a complex surgery and I don't want to do it if it's not compatible with the ZXPand+. (I have a 10Mhz Z80 so that won't be the issue).

Thanks for your advice - I am still pretty clueless about all this stuff but lockdown is a great time to learn.

[1024MAK]

As far as I am aware, the ZXpand and ZXpand+ require the ZX80/ZX81/TS1000 to run at their stock speed.

Although the SRAM and EEPROM chips may be okay with a faster computer, I’m not sure if the microcontroller that is the brains of the ZXpand and ZXpand+ can cope with a faster Z80.

Mark

[kmurta]

My ZX81 has the "why wait" mod and the ZXULA2 by Andy Rea and my ZXpand works well with this set, even with clock doubler active. I don't know about ZXpand+, I don't have one to test.