CURSOR and Commodore cassettes

From: Doug Spence <ds_spenc_at_alcor.concordia.ca>
Date: Tue May 11 09:51:14 1999

On 09-May-99, Doug Coward wrote:
>Doug Spence wrote:
>> Does anyone have the program "RACE" from Cursor #2?

> About a year ago, I transfered the first 15 or so CURSOR
>tapes to Commodore disk for Larry Anderson to put up on
>his BBS.

Hey, thanks! I don't know how long it's been since I visited his web
site (I even have a link to it on mine) but I don't remember all those
disk images being there before.

The "RACE" program from CURSOR #2 is on the petgms08.d64 archive.

This is actually the file I was trying to salvage with the sound
sampler. I'm glad I don't have to do that now, but I'm still interested
in the format.

BTW, I collected all twelve of those PET disks from Larry Anderson's
site, but I haven't transferred any of it to the PET yet. I've looked
at "RACE" on one of my C64 emulators, though, and it has "CURSOR #2, AUG
1978" as the remark on the first line, so I know it's the right one.

I'm eager to check out some of the machine code games.

>If I can find the tape, I can transfer it to
>the pc on the little C64 dev station I set up at work.

Wow! I guess you really MUST be the senior software engineer to have a
C64 dev station at work. :) (Not a comment on age, a comment on being
allowed to have cool toys at work.)

>Doug Spence wrote:
>>I need some information about the Commodore cassette storage format.
>>....snip.....
>>In the data portions, it appears as if every 20th wave is special

> About a year and a half ago, I took my shot at converting wave files.
>Unfortunately I had to move on to other projects just as I was making
>progress.
> First, IMHO if you are sampling at less than 44.1, you are making
>things too hard on yourself.

I'm limited to 40K, and I can't play samples at that rate unless I
change my screen mode. The sampler and software are Classic, and the
computer I'm using them on will be next year. The software only allows
sampling to memory, so I wanted to keep things small.

25.5K doesn't seem too bad, but after reading the rest of your
description and the sample output from your program, maybe it *isn't*
good enough. The differences between the short and long pulses aren't
very big. You're using 15 samples as your cutoff between short and
long, and I see that 14, 15 and 16 appear. That's shaving it pretty
close!

>With that information, I determine the byte like this:
> * the first two pulses are 1 and 1 - this is the sync bit.
> * the next two pulses are the low order bit
> * a 1 followed by a 0 is a 1
> * a 0 followed by a 1 is a 0
> * and the last two pulses is the parity bit

That's pretty darn cool.

Thanks!

-- 
Doug Spence
ds_spenc_at_alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/
Received on Tue May 11 1999 - 09:51:14 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:32:24 BST