Re: [PARPORT] "Magic Convertor II Plus" from Dotop Co., Ltd
Mon, 14 Jun 1999 19:46:26 -0400 (EDT)

> Is there somewhere a "software probe" for Linux which could tell me
> whether that device is SPP or EPP or what ?

That "software probe" would be a device driver for your adapter :-(

Until you can communicate with the thing, it isn't really possible to
determine what modes it can handle.

It's sort of like asking how fast a car can go, if you don't have an
ignition key.

> Is there somewhere a URL that would tell me what is "SPP" and "EPP" ?

Follow the link at the bottom of the linux-parport home page it takes you

where many of your questions might be answered.

In simple terms, the mode of the port determines the number of I/O cycles
required to move a byte to or from the remote device. SPP typically takes
about 5 cycles per byte, with some tricks getting that down to three on
some ports. PS/2 mode can do 2 cycles per byte and EPP can do 1 cycle
per byte. Most EPP ports can go down to 0.25 bytes per cycle. Of course,
the remote device has to be able to work as a peer to the port in each of
these modes. Devices made prior to '92 or so don't typically support EPP
modes, as few computers had ports that could do EPP transfers.

> I don't have any software for it. I emailed, but got
> no answer (yet).

Odds are if DOS drivers exist, Linux drivers could be made for it. But
if the DOS driver can only use SPP or PS/2 (also known as "bidirectional")
modes - there's no way you could use it to burn CDs which require a
higher sustained transfer rate than is possible with the older modes.

(Well, to be fair, it is _just_ possible to burn a CD in PS/2 mode at 1X
speed, but you need a lot of factors to align themselves in your favour.)

Grant R. Guenther

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This archive was generated by hypermail 2.0b3 on Mon 14 Jun 1999 - 19:47:58 EDT