4 PC printer ports

[Randy Day]

I'm wondering if there are any DIY projects
for putting 4 parallel ports on an ISA or
PCI card. I have a use for 4 ports in one
machine, and I can't find too many commercial
products like this any more...

 

[petrus bitbyter]

I'm wondering if there are any DIY projects
for putting 4 parallel ports on an ISA or
PCI card. I have a use for 4 ports in one
machine, and I can't find too many commercial
products like this any more...

Never seen. But the schematic of the original parallel port should be
someware. To make more ports, you'd only change the address decoder logic.
Unfortunately I have only one copy of 'a' parallel printerport schematic
that's so badly readable you need an old TTL databook and a good description
of the ISA card connector and one of the centronics connector and at least
some experience to recover the original text. So the pinnumbers, -names and
IC types. It uses some ten old LS-TTL chips. If you want it, I can make a
scan but you're warned.

petrus bitbyter

 

[Eeyore]

I'm wondering if there are any DIY projects
for putting 4 parallel ports on an ISA or
PCI card. I have a use for 4 ports in one
machine, and I can't find too many commercial
products like this any more...

If my memory serves me right the original PC spec only allowed for 3 printer
ports at the hardware / BIOS level.

Graham

 

[Puckdropper]

If my memory serves me right the original PC spec only allowed for 3
printer ports at the hardware / BIOS level.

Graham

03BCH, 0378H, 0278H to be specific.

You could have more, I'm sure, but good luck with software. If they're
not at one of those locations (and the 0278H is questionable at best)
you're probably not going to get to use them all.

Puckdropper

 

[Homer J Simpson]

I'm wondering if there are any DIY projects
for putting 4 parallel ports on an ISA or
PCI card. I have a use for 4 ports in one
machine, and I can't find too many commercial
products like this any more...

You could do it with a multiport card

http://www.digi.com/pdf/prd_usb_edgeport.pdf

or similar. Or USB to parallel.

 

[John Fields]

You could do it with a multiport card

http://www.digi.com/pdf/prd_usb_edgeport.pdf
or similar.

 

[Sjouke Burry]

Never seen. But the schematic of the original parallel port should be
someware. To make more ports, you'd only change the address decoder logic.
Unfortunately I have only one copy of 'a' parallel printerport schematic
that's so badly readable you need an old TTL databook and a good description
of the ISA card connector and one of the centronics connector and at least
some experience to recover the original text. So the pinnumbers, -names and
IC types. It uses some ten old LS-TTL chips. If you want it, I can make a
scan but you're warned.

petrus bitbyter

I remember isa cards with one port only.
You had to put a strap on to select 1/2/3/4,
and the lpt bios area supports 4 printerports.
So if you have the extra slots, and can find
the cards........

 

[Lionel]

I'm wondering if there are any DIY projects
for putting 4 parallel ports on an ISA or
PCI card.

Not that I know of, but read on...

I have a use for 4 ports in one
machine, and I can't find too many commercial
products like this any more...

If you want them in order to run a bunch of printers, the easy answer
is to use networked or USB printers, of which you can attach as many
as you like. If you need to run existing, parallel-only printers, you
can buy USB to parallel converters.
If you want the ports for general I/O purposes (eg; machine control),
you can buy kit or pre-built USB parallel I/O modules very easily, &
they're usually also available with extras like analog I/O ports &
high level language libraries.
'

 

[Lionel]

03BCH, 0378H, 0278H to be specific.

You can also add more to the official experimental I/O addressing
range that starts from 0x300, with the same caveats about software
support:

You could have more, I'm sure, but good luck with software. If they're
not at one of those locations (and the 0278H is questionable at best)
you're probably not going to get to use them all.

If you don't mind configuring them manually, it's actually not
difficult.

 

[Homer J Simpson]

Those all seem to be solutions which will support a number of serial
(not parallel) ports.

Could be. I never saw more than 3 parallel ports on a PC.

That's the ticket! got a URL?

They're all over eBay (720 items found for usb parallel) or try any Staples
etc.

 

[Randy Day]

Randy Day wrote:




If my memory serves me right the original PC spec only allowed for 3 printer
ports at the hardware / BIOS level.

Graham

Somehow I got it in my head it was 4, but you could be right.
That would explain why I saw some 3 port cards, but no 4's.

Oh, well, a slight readjustment of plans is in order...

 

[Eeyore]

Somehow I got it in my head it was 4, but you could be right.
That would explain why I saw some 3 port cards, but no 4's.

Oh, well, a slight readjustment of plans is in order...

You might be able to 'frig it' but it'll need some code I expect. Like a Bios
extension.

Graham

 

[Bob Masta]

Not that I know of, but read on...


If you want them in order to run a bunch of printers, the easy answer
is to use networked or USB printers, of which you can attach as many
as you like. If you need to run existing, parallel-only printers, you
can buy USB to parallel converters.
If you want the ports for general I/O purposes (eg; machine control),
you can buy kit or pre-built USB parallel I/O modules very easily, &
they're usually also available with extras like analog I/O ports &
high level language libraries.

If the latter case, the other thing you can do is make a little
multiplexer. There are lots of ways this can be done, but
the simplest is to use 2 bits from the CTRL port to select
one of 4 addresses that you decode to 4 separate lines,
one for each of 4 octal latch enables. The latches are all
connected in parallel to the DATA port. Now when you
write data, it only goes to the selected latch pins. You
can easily extend this scheme at will.

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

[petrus bitbyter]

Somehow I got it in my head it was 4, but you could be right.
That would explain why I saw some 3 port cards, but no 4's.

Oh, well, a slight readjustment of plans is in order...

Only the first BIOSes accounted for four printer ports. Newer ones use the
space of the fourth port for controlling some memory extension. FAIK even
most or all XT machines could have only three printer ports (as far as the
BIOS concernes.)

petrus bitbyter

 

[Sjouke Burry]

Somehow I got it in my head it was 4, but you could be right.
That would explain why I saw some 3 port cards, but no 4's.

Oh, well, a slight readjustment of plans is in order...

From Ralf Browns (int53) listings:
4 are possible , see below.
----------M00400006--------------------------
MEM 0040h:0006h - BASE I/O ADDRESS OF FOURTH SERIAL I/O PORT
Size: WORD
Note: the BIOS sets this word to zero if is unable to find more than three
serial ports at the addresses it is programmed to check at boot
SeeAlso: MEM 0040h:0000h,MEM 0040h:0002h,MEM 0040h:0004h,MEM 0040h:0008h
SeeAlso: MEM 0040h:007Fh
----------M00400008--------------------------
MEM 0040h:0008h - BASE I/O ADDRESS OF FIRST PARALLEL I/O PORT
Size: WORD
Notes: the BIOS POST routine fills in the parallel port address fields in
turn as it finds parallel ports. All fields beyond the last one
for which a valid parallel port was found are set to zero.
the BIOS INT 17 handler uses these fields to address the parallel
ports
SeeAlso: MEM 0040h:0000h,MEM 0040h:000Ah,MEM 0040h:000Ch
----------M0040000A--------------------------
MEM 0040h:000Ah - BASE I/O ADDRESS OF SECOND PARALLEL I/O PORT
Size: WORD
Note: zero if fewer than two parallel ports installed
SeeAlso: MEM 0040h:0002h,MEM 0040h:0008h,MEM 0040h:000Ch
----------M0040000C--------------------------
MEM 0040h:000Ch - BASE I/O ADDRESS OF THIRD PARALLEL I/O PORT
Size: WORD
Note: zero if fewer than three parallel ports installed
SeeAlso: MEM 0040h:0004h,MEM 0040h:0008h,MEM 0040h:000Ah,MEM 0040h:000Eh
----------M0040000E--------------------------
MEM 0040h:000Eh - BASE I/O ADDRESS OF FOURTH PARALLEL I/O PORT (pre-PS/2)
Size: WORD
Note: zero if fewer than four parallel ports installed
SeeAlso: MEM 0040h:0008h,MEM 0040h:000Ah,MEM 0040h:000Eh"BIOS DATA"
----------M0040000E--------------------------
MEM 0040h:000Eh - SEGMENT OF EXTENDED BIOS DATA SEGMENT (PS/2, newer BIOSes)
Size: WORD
SeeAlso: MEM 0040h:000Eh"PARALLEL"

 

[Baron]

I remember isa cards with one port only.
You had to put a strap on to select 1/2/3/4,
and the lpt bios area supports 4 printerports.
So if you have the extra slots, and can find
the cards........

Funny you should mention that ! I came across an old 8 bit ISA LPT card
earlier today with an 8 pin dil header that you soldered wires across
to select the port. I remember that you could turn the header plug
around to select 1 or 3 and a second one to get 2 or 4 !

I always used to wonder why jumpers and pins weren't used.

 

[Rich Grise]

Funny you should mention that ! I came across an old 8 bit ISA LPT card
earlier today with an 8 pin dil header that you soldered wires across
to select the port. I remember that you could turn the header plug
around to select 1 or 3 and a second one to get 2 or 4 !

I always used to wonder why jumpers and pins weren't used.

Because a header plug in a socket is cheaper.

Cheers!
Rich

 

[Baron]

Because a header plug in a socket is cheaper.

Cheers!
Rich

Mmm. I would have thought the reverse ! Probably today it would be! 20
years ago ???

 

[Michael A. Terrell]

Mmm. I would have thought the reverse! Probably today it would be! 20
years ago ???

More important, if the board was to be used on a production line it
takes less time to change the configuration, and harder to screw up.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Homer J Simpson]

Note: zero if fewer than four parallel ports installed

But what will you do for interrupts?