| Title: | Atari ST, TT, & Falcon |
| Notice: | Please read note 1.0 and its replies before posting! |
| Moderator: | FUNYET::ANDERSON |
| Created: | Mon Apr 04 1988 |
| Last Modified: | Tue May 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 1433 |
| Total number of notes: | 10312 |
I'm thinking about hanging a few experimental circuits off the parallel port of my ST. From my experience with my old 8-bit (I blew the joystick ports) I thought it would be wise to buffer the port. Can any h/w person tell me whether I'd be OK with LS octal buffers, and whether I can take the power for the buffers from the port ? Also, has anybody any experience of hanging stuff off the cartridge port ? Dave.
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 326.1 | Buffer | DORIS::JAMES | Left Handed People are Super Natural | Thu Dec 01 1988 15:39 | 8 |
I too am going to do a similar thing and there is a switch using
CMOS analogue switches which will buffer the port. The circuit appeared
in one of the UK magazines earlier this year and also gave some
programming info to output and input to the switch. If you're
interested I'll look it out. I haven't interfaced to the cartridge
port as I have a clock sticking out there. There is however a UK
company that can supply a mother board for the port.
...Howard
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| 326.2 | Should buffer the port | TEA::PETERS | Don Peters, CTS1-2/H6, 287-3742 | Thu Dec 01 1988 16:01 | 9 |
Be aware that the parallel port is very weak in its drive requirements. A number of ST users have found that the parallel port cannot drive some printers. Specifically, the parallel port expects to see load resistors of no lower than about 3.3k ohm. Anything lower and the pulldown transistors in the ST won't be able to handle it. So the best idea is to buffer the port. I don't think the port supplies any power, but I may be wrong. | |||||
| 326.3 | 8 bit I/P and O/P !! | RDGENG::KEANE | Fri Dec 02 1988 11:01 | 16 | |
Hi,
I agree with everything thats gone before, especially about the
port drive capability. It definately needs buffering. What isnt
generally appreciated is that the port is BI-directional. You can
read 8 bit data in as well as outputting. I have the same articles
re constructing a small board that buffers and provides 8 bit I/O,
as well as running a parallel printer connected as well. This card
derives its 5 volts from an extra connection made inside the ST
and brought out through the rear parallel connector. It obviously
needs a bit of programming to sw between input output and line printer,
an type in is provided (I think).
Cheers
Pat K.
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