5 ms·
>(Incidentally, the 6502 can do this in 10 bytes and 14 cycles. The Z80 is terrifyingly slow.) It's misleading to call the Z80 "terrifyingly slow" based on cyc
by mrob 8y ago
>(Incidentally, the 6502 can do this in 10 bytes and 14 cycles. The Z80 is terrifyingly slow.)
It's misleading to call the Z80 "terrifyingly slow" based on cycle counts without mentioning that it clocked higher than the 6502. E.g. the Apple II ran at just over 1MHz, while the ZX Spectrum ran at 3.5MHz (although with wait states for accessing the memory area shared by the graphics hardware).
- tonyedgecombe 8y agoThat's a little unfair, the BBC Micro ran at 2 MHz and was released before the Spectrum.
- masklinn 8y agoIt's not wrong though, the 6502 was much slower clocked that equivalent contemporaries. However IIRC most contemporary architectures were closer to the Z80, so the 6502 was considered impressive because it was competitive despite a much lower clock rate.
- jonsen 8y ago1 MHz clock on the 6800 family of processors, including the 6502, is equivalent to 2 MHz clock on the Z80. The 6800 architecture used a so called two-phase clock. Each phase, positive and negative, of the clock cycle was used to do work.
- timbit42 8y agoI would suggest it is between 2 and 3 times, but it depends on what kind of code you are running.
- timbit42 8y agoA 2 MHz 6502 is approximately equivalent to a 6 MHz Z80, give or take 1 MHz depending on what you're doing.
- Doctor_Fegg 8y agoYep. The Amstrad CPC was an effective 3.3MHz. Most 8-bit machines of the early 80s had reasonably comparable CPU performance: the real speed differentiators were the graphics hardware (Spectrum fast because you had so few colour bytes to write, CPC slow - until you learned how to scroll with the CRTC) and, if you used it, the efficiency of the BASIC/firmware. There was a 16MHz Z80: Amstrad briefly built a machine on it in the 1990s (the PcW16).
- opencl 8y agoTI still sells 15Mhz Z80s in their TI84 graphing calculators.
- mavhc 8y agoAnd still charges what they cost in the 80s
- vanderZwan 8y agoI'm kind of wondering why there isn't an open hardware calculator yet. Given the mark-up most of these brands have, it might actually be viable.
- colejohnson66 8y agoThe ACT and SAT require certified calculators
- vanderZwan 8y agoWell, I imagine we could get citizen funding for that. EDIT: Oh, the certificate is with the product? Well, there might be some smaller players who currently can't compete with TI who could handle the production side. Hardware-wise it should definitely be easy enough to create a cheaper calculator just as capable of meeting the requirements, no?
- 8y ago