Sinclair ZX80 / ZX81 / Z88 Forums

Aritm is a game that trains you in mental calculation. It only teaches what is necessary to know in order to calculate manually using pen and paper. It adapts and asks more about what you answered wrongly before. You can configure which problems you want. In order to finish Aritm you need to answer each problem correctly one more time than wrongly.

Aritm needs a ZX81 with 16 KiB RAM or more and is written in pure ZX81 BASIC.

Future versions will probably support larger text in game and might have AY-sound effects.

I've not tested it on my real ZX81, but it works in emulators. Maybe it's best to run it in FAST mode, but it runs by default in SLOW mode.
E.g. in Linux: Aritm is available for many platforms including graphing calculators, Java phones, spread sheets, and common retro computers: http://aritm.orbin.se (Unfortunately only in Swedish, but can probably be automatically translated by your browser.)

Aritm is open source (GPLv3) and is tested using an automatic testing system: https://github.com/mobluse/aritmjs
The code is a bit strange because I wrote it first for TI-83 BASIC and ported it to TinyBASIC (32 bit) and then ported it to ZX81 BASIC via GW-BASIC and ZX Spectrum BASIC. I should ideally have a version for each BASIC that uses the features of that BASIC, but it's not there yet.

There is one strange thing: When I run it in the emulator xz81 the text is only in the top of the screen as if it is saving RAM by making a smaller display file, but this problem doesn't exist in zesarux. Does anyone know why this is so? I updated the p-file with a slightly faster version from 2022-06-11.

How very nice. Both in interface and in presentation.

I have completed "Division". I attempted to answer as fast as possible, and it brought back to mind our impromptu school competitions in the spring of 1978. There was always one guy who could answer correctly without (seemingly) thinking, whereas I would sometimes have to think about it

Question: Is "ARITM" short for "aritmetisk"?

I'm using the ZX81 emulator "EightyOne" and it uses the entire screen. Exercises appear at the bottom, then scroll up after answering. I see the same using the No$zx emulator

I like it better in SLOW mode so that the scrolling appears. Although it is quick enough, using the emulator "32x Speed" option helps. 100 questions are a lot for one session

Aritm is short for "aritmetik" i.e. arithmetic in English.

Aritm for ZX81 works better if you use the improved ROMs such as "X2": https://sinclairzxworld.com/viewtopic.p ... 327#p40327

When I ran Aritm for MS-DOS in C (1992) I also had flashbacks to classroom competitions in the 70s which I was not good at.