In the z80 opcode table, it says that JP uses 10 cycles and JR uses 12/7 cycles. Does 12/7 cycles mean that it takes 12 on a jump and 7 on a pass, or the other way around?
It takes 12 cycles if it needs to jump and 7 if it doesn't need to jump.
Yeah, on the z80 "jp" is generally faster if you're making the jump but one byte larger, "jr" is typically slower (except when using the conditional version where the condition is false/no jump is taken) but one byte smaller. It's a convoluted case of the classic "size vs. speed".

Like Hot_Dog posted, i like the formatting of the ASM in 28 Days instruction set and that's my go-to reference when i need to confirm how many T-states an instruction takes.
Register to Join the Conversation
Have your own thoughts to add to this or any other topic? Want to ask a question, offer a suggestion, share your own programs and projects, upload a file to the file archives, get help with calculator and computer programming, or simply chat with like-minded coders and tech and calculator enthusiasts via the site-wide AJAX SAX widget? Registration for a free Cemetech account only takes a minute.

» Go to Registration page
Page 1 of 1
» All times are UTC - 5 Hours
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum