Would the HP-15C Limited Edition Firmware Age Away?

[Greg]

Just an update. It looks like, and I could be reading Firefox wrong, that I'm overtaxing it somewhat. It's not its fault. My code could have been written better.

As far as I can tell, it looks like I'm requesting a series of digits ("E", "r", "o") and it is trying to download them but before it gets there, I request them again and it starts over. What we see is the one it did manage to download ("r") and nothing else.

I am running the HP-29C emulator nicely in Firefox 59.0.1 (on Win 10 so far) but with all the tests I'm not sure I can repeat the sequence that got it there. My best guess is it was simply clicking the "install" link and waiting for the "installed" message. What I saw when I did that was each file download in sequence and then the whole thing run. I did try clearing the Firefox cache and retesting but it looks like it retained some stuff as I couldn't get the " rr r" display again.

The Woodstock calculators run at about 200 kHz. That's not as much as it sounds because data gets shipped around serially in 56 bit chunks so it works out to about 3000 microcode instructions per second. Any emulator, even in a browser, has to match that speed. That's 0.3 mS per instruction. I update the display every 80 of those, ie every 24 mS. With a 12 digit display, the browser has somewhere between 2-24 mS to download a (small) picture - depending on whether it does multiple GETs at a time. Every 24 mS I ask again.

I think IE and Chrome are saying, "I already have this one in my list of things to get" and Firefox is saying, "I don't have this yet so I'd better add it to the list".

I could be wrong, but that's what it looks like to me.

There are no javascript exceptions being triggered so it doesn't seem to be a divide by zero error or a case of an unsupported property in this browser.

The workaround is probably to do the "install" as that downloads the files up front. More testing is required.

The longer term fix is to not request pictures I just asked for (eg if the display isn't changing).