🚀 go-pugleaf

In article: <19990413.1703.4696snz@michaels.demon.co.uk>  
4ms2u$ms@michaels.demon.co.uk (Michael Salem) writes:
> 
> Roger J.Hamlett wrote useful information about types of parallel 
port:
> 
> It's worse than that! Some BIOSes give you the option of SPP 
> (Standard Parallel Port), Bidirectional, EPP, ECP mode something 
> (1.1?), ECP mode something else (1.3). And even SPP is capable of 
> some degree of bidirectional operation (you can use it with input 
> devices such as tape streamers).
Yes I was 'simplifying'. The SPP, allows input on the handshakeing 
lines only. This gives 'nibble' wide input (as opposed to 'byte' wide 
on the more sophisticated types), and correspondingly is a lot 
slower for input transfers. The differences on the Bi-dir, versus EPP 
modes is how the direction switching is controlled (the EPP mode 
allows a signal line to reverse direction). The ECP modes affect how 
the DMA is handled, and the latter modes require larger buffers.
 
> My advice is to start with the most capable mode (the last as you 
> cycle through the options in the BIOS). If using Windows, make sure 
> Windows has set the port in the same way as the BIOS. If it doesn't 
> work, set it to SPP and see if it works. If so, try more advanced 
> options. 
Yes.
 
> Advantages of advanced types: are faster for some purposes (only if 
> speed is limited by data transfer, rather then the peripheral 
> itself). Often let peripherals report information to the computer 
> ("printer out of ink").
> 
> Disadvantages: if using an advanced port with a printer cable that 
> doesn't have all 25 lines connected (many old cables; some new, 
cheap 
> cables), the printer may not work properly. Some peripherals have 
> problems.
Very true.
It also often suprises people, how fast the parallel port in the more 
sophisticated modes has got. A modern machine can transfer something 
over 3MB/sec, over the parallel port, against USB, at only about 
1MB/sec. The 'advantage' of USB, is the connection simplicity (cables 
are easy, and you don't have all these 'modes' to worry about - at 
least until 'USB2' arrives :-), and with the parallel port, it is 
usual to have more problems when multiple devices are attached.

Best Wishes

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