late comment but, edition 2 is bugged. took me till now to realize itMcKlaud wrote: ↑Mon Nov 05, 2018 9:15 pm regarding your second question, try these:
If you have Zeddy with the bugged ROM results might surprise you.Code: Select all
PRINT PEEK 3823 PRINT SQR 0.25 PRINT 0.25 ^ 2 PRINT 4 - 0.0000000001 PRINT SQR 0.0625
Difference between New rom and Old Rom
Re: Difference between New rom and Old Rom
In Heck, there are two options for perpetual torment:
Eat the Puckerberry and suffer for eternity:
drink nothing but a cocktail of The Last Dab and Mexican Cake blended and served with
habanero slices
Eat the Puckerberry and suffer for eternity:
drink nothing but a cocktail of The Last Dab and Mexican Cake blended and served with
habanero slices
Re: Difference between New rom and Old Rom
also noticed a weird thing. On the old rom, entering one of the programs apparently intrudes into screen memory (it prints symbols instead of doing what it's supposed to) and crashes the computer on the old rom. 5th program down.Crayon21 wrote: ↑Sun Apr 04, 2021 12:11 amlate comment but, edition 2 is bugged. took me till now to realize itMcKlaud wrote: ↑Mon Nov 05, 2018 9:15 pm regarding your second question, try these:
If you have Zeddy with the bugged ROM results might surprise you.Code: Select all
PRINT PEEK 3823 PRINT SQR 0.25 PRINT 0.25 ^ 2 PRINT 4 - 0.0000000001 PRINT SQR 0.0625
In Heck, there are two options for perpetual torment:
Eat the Puckerberry and suffer for eternity:
drink nothing but a cocktail of The Last Dab and Mexican Cake blended and served with
habanero slices
Eat the Puckerberry and suffer for eternity:
drink nothing but a cocktail of The Last Dab and Mexican Cake blended and served with
habanero slices
Re: Difference between New rom and Old Rom
All the ROMs could be classed as bugged as they still have the rounding errors inherent in floating point maths.
There was a couple of articles by maths guru Frank O'Hara in ZX computing that explained this in great depth along with work-arounds in BASIC.
Internally the ZX81 is accurate to 9.5 digits of accuracy but after rounding displays only 8.
So asking for an accurate resolve of PRINT 4 - 0.0000000001 and getting an erroneous result from a device that for all practical purposes is accurate to 8 digits is entirely expected considering this is an 11 digit decimal.
The "bug" was an admitted mistake by John Grant,owner of Nine Tiles authors of the ROM, in the floating point division routine therefore a bug whereas things like the example above are due to the aforesaid rounding errors and accuracy of held numbers rather than mistaken ROM coding.
There was a couple of articles by maths guru Frank O'Hara in ZX computing that explained this in great depth along with work-arounds in BASIC.
Internally the ZX81 is accurate to 9.5 digits of accuracy but after rounding displays only 8.
So asking for an accurate resolve of PRINT 4 - 0.0000000001 and getting an erroneous result from a device that for all practical purposes is accurate to 8 digits is entirely expected considering this is an 11 digit decimal.
The "bug" was an admitted mistake by John Grant,owner of Nine Tiles authors of the ROM, in the floating point division routine therefore a bug whereas things like the example above are due to the aforesaid rounding errors and accuracy of held numbers rather than mistaken ROM coding.