Sinclair ZX80 / ZX81 / Z88 Forums

Hi Panther, where does the 726 value come from? The standard screen is 22 lines x 32 columns so 704 positions. Also, if you press the CONT key, your first routine will print another screen of characters... Thats because the JR NZ tests the value of the A Register, you are decrementing BC. So, the r...

Hi peeps, New to the forum and looking for guidance as I take my first steps into ZX81 machine code !! I’ve been reading through ‘Mastering Machine Code on your ZX81’ and I’m understanding it so far but I’m a little confused with one of the most basic things; Printing to the screen !! One of the exa...