PETSCII design

[nikoniko]

When Commodore developed PETSCII, why did they switch upper/lower case compared to the ASCII standard?

[hydrophilic]

Good question!  I'm guessing its a technical issue related to the fact that many 8-bits only had uppercase to begin with.  Isn't that so with some PETs?

And besides the alpha characters, why are there differnces between some of the characters between uppercase/graphic and lowercase/uppercase fonts??

If you're developing your own program, just change the font and don't bother converting!  My 2 cents.

But I love the graphic characters.  Great for windows, bar charts, and card games!

[Christian Johansson]

Actually, Bill Gates claims that Micro-soft created the graphics characters. Here's an excerpt from an interview with Bill Gates.

...
In terms of Commodore PET, they started with us from the very beginning. Because we helped Chuck Pedal, who was at Commodore at that time, really think about the design of the machine. Adding lots of fun characters to the character set, things like smiley faces, and suit symbols. That was the first machine we did that had this wild extended character set. All these machines started out using cassette-based storage, where we could store about 1,200 baud worth of data on these cassette tapes.
...

The complete interview can be found here: http://americanhistory.si.edu/collections/comphist/gates.htm

[hydrophilic]

That's pretty cool.  I never thought Mr.Gates knew Mr.Pedal.  Thanks for the link!

Do PETs really have a smiley face character?  I know PETSCII on VIC and later do not.

[nikoniko]

Me thinks Bill is confused. Wasn't it Extended ASCII that had two smiley characters (one light, one dark)? I seem to recall that some text-mode DOS games (eg. Kingdom of Kroz) used them for player characters.

And since when is baud a unit of storage rather than symbol transmission rate?

[Andrew Wiskow]

And since when is baud a unit of storage rather than symbol transmission rate?

I was wondering the same thing!  :/

-Andrew

[Guest]

And since when is baud a unit of storage rather than symbol transmission rate?

I was wondering the same thing!  :/

-Andrew

When the storage of cassette tapes is directly tied to the length of the tape, and tapes varied wildly in length back then.  With reel-to-reel, you literally didn't know how much tape you had other than taking a guess by looking at a completely wound reel, but even then you had to know the thickness of the tape to know how much was actually there.

[nikoniko]

But doesn't baud always refer to symbol rate? Wikipedia's description pretty much sums up how I've always understood it, but my understanding may be too narrow:

Symbol rate is measured in symbols-per-second, hertz (Hz), or baud (Bd).

The term baud rate is synonymous with symbol rate, but is less frequently used today as it has in the past been commonly misused to mean bit rate or data rate.

The symbol rate of a signal can be directly measured using a oscilloscope (in the time domain, measuring the time between transitions) or a spectrometer (in the frequency domain, measuring the bandwidth).

The only sense in which I could see 1200 baud expressing an amount of storage would be if it referred to exactly 1 second of cassette tape. Does cassette transfer use 1 bit symbols or 1 byte or what? If 1 bit, were there really cassettes with such little storage (150 bytes per side)? For so few bytes of space, it might have been reasonable for a hobbyist to save the expense of tapes and just reenter machine code by hand whenever a different routine was needed. Or could you load multiple tapes in succession? If so, that might not have been so bad. Again, if a symbol is 1 bit, a 1K program could have fit on a few tapes if using both sides. I guess that's no worse than some of the disk swapping nightmares that would come later.