4 ms·
Not what I was expecting, normally I would expect a real time clock to keep running when the system was turned off, so you would be able to have accurate curren
by snops 7y ago
Not what I was expecting, normally I would expect a real time clock to keep running when the system was turned off, so you would be able to have accurate current date/time.
I'm also very surprised to see that apparently the Apple II didn't have something like this built in already, were all delays implemented as busy loops?
- tlb 7y agoYes. The CPU ran at 1 MHz and instruction timings were deterministic and well-documented, so it wasn't hard to write a delay loop for any number of microseconds. There were sound synthesizers that could play chords, all based on toggling a digital output connected to a speaker with the right timing patterns.
- pvg 7y agohttps://www.youtube.com/watch?v=oo46kKaHA3E&feature=youtu.be&t=24 https://www.youtube.com/watch?v=oo46kKaHA3E&feature=youtu.be...
- scarface74 7y agoYou could even make intelligible speech to text by toggling the one bit speaker at the right frequency. https://en.wikipedia.org/wiki/Software_Automatic_Mouth https://en.wikipedia.org/wiki/Software_Automatic_Mouth And I found a web version that sounds just like it. https://simulationcorner.net/index.php?page=sam https://simulationcorner.net/index.php?page=sam
- pvg 7y agothe Apple II didn't have something like this built in already I don't think any of the popular 8-bit machines did. It might make more sense if you consider it from the other end - what would you do with an accurate date and time on such a machine?
- snops 7y agoAh, by "this" I meant the articles 60Hz timer, not the proper date/time peripheral I imagined the article to be from the title. For a 60Hz timer, just being able to have a delay without needing to count all the instructions in between when programming.
- pvg 7y agoThe Apple //e had a way to track vertical retrace but that's a fairly late model. It was a sort of 'interrupt-free' system anyway so given that and its overall slowness, cycle counting ends up being the practical default.
- sehugg 7y agoI mean -- timestamp your files in ProDOS? Control your sweet X10 home automation setup? Clock your employees in and out? Run your BBS?
- pvg 7y agoIf you were that fancy, you bought a clock card, discovered it didn't actually work with ProDOS, tried to hack it or sent it back, etc.
- scarface74 7y agoIt didn’t? I never had a real clock card for my Apple //e, but I had a simulated one with my Apple//e card in my LCII. I never knew the real ones didn’t work with ProDOS.
- pvg 7y agoOh I meant hypothetically - some of them did and some of them didn't since some of the cards pre-dated ProDOS. What I was trying to say was, if you wanted to do something where an RTC made sense, you would almost certainly have to buy extra hardware to do the something itself as well - it's not like the machine had as much as a serial port. I imagine the //e card gave a view of a nigh-impossibly tricked out //e, as would make sense for a //e that has an entire Mac as its 'peripherals'.
- scarface74 7y agoYep https://en.wikipedia.org/wiki/Apple_IIe_Card https://en.wikipedia.org/wiki/Apple_IIe_Card Also, it would translate ImageWriter output to QuickDraw and you could print to any printer connected to your Mac.
- Max-q 7y ago> I don't think any of the popular 8-bit machines did. The Commodores had timers in their 6522/6526 chips, where an RTC was set up. In Basic, it could be accessed via the TI or TI$ variables (integer and string respectively). Not having timers or VBlank interrupts were unusual. The Apple ][ was an early and hacked-together design by Woz, not at all made for a mass market. Just look at the graphic formats :-/
- classichasclass 7y agoNot quite. TI$ on the C64 was maintained by the 60Hz Timer A interrupt (in fact, remarkably similar to this method, but using IRQ instead of NMI and built into BASIC). You are correct that the CIAs have Time-of-Day clocks, but BASIC doesn't leverage those. However, some apps like GEOS do.