3 ms·
I never understood why CPUs were not running at max clockspeed by default. Was it because some applications were clock dependant?
by tirant 7y ago
I never understood why CPUs were not running at max clockspeed by default. Was it because some applications were clock dependant?
- masklinn 7y ago> I never understood why CPUs were not running at max clockspeed by default. Pretty sure the machines were usually shipped in "turbo" configuration. > Was it because some applications were clock dependant? Lots. The original PC CPU (8088?) ran at 4.7MHz or something. Lots of early games (not only games but that was very obvious for them) were developed with a "fixed hardware" mindset and would rely on busy loop and CPU clock for the "game clock". So when you got a faster CPU the entire game would speed up. Things got funky on an 8MHz 268 and outright screwy on a 386 or 486 (whose latter models reached 100MHz).
- JoeAltmaier 7y agoOne of the crimes propagated from that issue was, Intel deliberately crippled the data-move instruction because folks who shipped lots of software (OK Microsoft) used it for timing. So as CPUs increased by an order of magnitude, the one-byte ultra-fast data move opcodes become the slowest way to move data. A crime against humanity. For this reason I'd asked Intel (as a senior programmer at one of Intel's largest CPU chip consumers) for a fixed-rate timer register when they made the 386 e.g. 1MHz free-running counter regardless of CPU speed. While they did implement other requested features (breakpoint registers) somebody screwed up the timer feature and made it full-clock-speed and accessible only thru a privileged instruction. Thus useless for applications.