K-2 Kradle?

[1024MAK]

I timed how long it takes between power up and the K cursor appearing with a 16k RAM expansion, it was about 3 seconds for a UK spec ZX81. The standard BASIC ROM only looks for 16k of RAM (or less), so any extra RAM is ignored by the ROM, so will not affect the "start-up" time.

With BASIC, to use any RAM beyond the 16k bytes that it is expecting, you have to change a system variable (known as RAMTOP) with a POKE command. Then a NEW command. The instructions for the 64k byte Memotech RAM pack here explain more...

However, if you only want to store data above the normal RAMTOP limit, you can. No need to tell the BASIC system.

Note that the ROM does not perform a RAM test, it only tests to see how much RAM there is up to 16k bytes. All extra RAM is not tested or checked by the ROM.

Mark

[draketungsten]

@Moggy Thanks for the PDF and the tips. I saw a lot of demos that were cross-compiled on desktops and the speed possible with this thing is surprising. All I've read about Forth really is it's closer to machine than BASIC and so much faster, and at this time the only working chip on my board until I figure out why the Kradle apparently blocks boot.

@1024MAK Thanks for that, I wasn't aware it stops scanning at 16k. If I ever get the BASIC ROM to boot I'll give that POKE a try, not that I'd be doing anything with it but maybe in the future...