[Color Computer] Re: [Coco] DSK images to coco

[John R. Hogerhuis]

On Mon, 2005-05-02 at 14:19 -0500, George Ramsower wrote:

>  I still average about 240 cps on downloads to the coco, using a hard drive
> for storage. A floppy would slow it down a lot, but not to 80 cps. I think
> possibly, the null modem cable is the culprit. At 19.2 kb, there will be
> lots of errors and retries. I would try it again at 1200 or 2400 to see if
> it speeds up. This will prove if RTS, CTS, DTR, DSR are needed.
>  Sending data to a coco at 19.2 just won't work, at least not without some
> handshaking between the computers. I gave up speeds over 4800 with all the
> signal lines working.
>  The coco can SEND data at a faster rate kuz wherever it's sending it to
> today, is most likely fast enough to receive it. I've found that the coco is
> still limited on how fast it can send data. If I use 9600baud, it doesn't
> send much faster than 4800, or about 450 cps average. The packet bursts seem
> to go quicker, but this little guy still has to group them up to send them.
> 

Boisy's Drivewire goes much faster over the bitbanger! If you look at
the published protocol spec, it is operating at half-duplex and doesn't
do anything else while it's transferring. Also the PC never originates
communication, so between packets the coco can take its time. But during
the burst of traffic in either direction it keeps up. I think DW goes at
38400 on coco and 57600 on coco3.

I worked up some asm examples that lead me to believe with DP addressing
you might even be able to double that, assuming there's not electrical
issues.

Interestingly, I was helping Boisy with some tests a while back and the
biggest problem seemed to be the PC side getting too busy and dropping
characters, IIRC.

-- John.