On Sun, 21 Mar 2010 13:07:01 -0800, the renowned Robert Baer <robertbaer@localnet.com> wrote:>whit3rd wrote: >> On Mar 20, 7:33 am, GreenXenon <glucege...@gmail.com> wrote: >> >>> I keep hearing about Universal Serial Bus [USB]. Why hasn't a >>> Universal Parallel Bus [UPB] been implemented yet? >> >> It has been done, twice. IEEE-488 for instruments, and SCSI >> for small computers. >> >> Expensive cables made IEEE-488 a boutique item, and SCSI >> (which got up to 320 MBytes/sec) was usually kinda high-end >> Most Macintosh computers from 1986 to 1998 used SCSI. >> >> Parallel ports DO NOT COUNT, because they aren't a bus; >> the early ones weren't even bidirectional, and there was >> never any good support for more than two connections. >> Bus, from 'omnibus' meaning 'for everyone' implies that all >> bus signals are served by all devices, not just two. > Well, it turns out that the ORIGINAL PC/XT in 1980 had all of the >hardware on board to do full 8-bit I/O. > Are you perhaps alluding to an earlier version??You sure about that? I recall that inputs had to be done 4 bits at a time (nibble mode) to assure compatibility. I have a chunk of code around somewhere that defines all the printer control signals in a sensible way for general purpose control (some are inverted IIRC...) Checking Jan Axelson's seminal publication "Parallel Port Complete", I see she says:- The original PC's parallel port had eight outputs, five inputs, and four bidirectional lines.... On many newer PCs, the eight oututs can also serve as inputs..." Now, the really crotchety old farts will remember that there was a hardware modification you could do to the original parallel port cards (wot used LS TTL parts) to cut the /ENABLE pin of the output latch so it wasn't permanently grounded, and jumper it to allow it to be controlled for birectional I/O, but I wouldn't claim that this "had all the hardware on board" when soldering irons and dremels are involved... Of course all this stuff has been in a corner of an LSI chip for decades now, so you're stuck with whatever IP is used for the chip, but you used to be able to do it. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Universal Parallel Bus -- why not?
Started by ●March 20, 2010
Reply by ●March 21, 20102010-03-21
Reply by ●March 21, 20102010-03-21
On Sat, 20 Mar 2010 21:05:33 -0400, Bitrex wrote:> SCSI-1 compact flash readers sell for big money on Ebay for > retrofitting older equipment.Pro photographers with Macs? -- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)
Reply by ●March 21, 20102010-03-21
On Mar 21, 2:07=A0pm, Robert Baer <robertb...@localnet.com> wrote:> whit3rd wrote: > > On Mar 20, 7:33 am, GreenXenon <glucege...@gmail.com> wrote: > > >> I keep hearing about Universal Serial Bus [USB]. Why hasn't a > >> Universal Parallel Bus [UPB] been implemented yet? > > > It has been done, twice. =A0IEEE-488 for instruments, and SCSI > > for small computers. > > > Expensive cables made IEEE-488 a boutique item, and SCSI > > (which got up to 320 MBytes/sec) was usually kinda high-end > > Most Macintosh computers from 1986 to 1998 used SCSI. > > > Parallel ports DO NOT COUNT, because they aren't a bus; > > the early ones weren't even bidirectional, and there was > > never any good support for more than two connections. > > Bus, from 'omnibus' meaning 'for everyone' implies that all > > bus signals are served by all devices, not just two. > > =A0 =A0Well, it turns out that the ORIGINAL PC/XT in 1980 had all of the > hardware on board to do full 8-bit I/O. > =A0 =A0Are you perhaps alluding to an earlier version??The "standard" PC printer port of the PC/XT was the 8255. This chip could go both directions. Later PCs integrated the printer port function into a chip and removed some of the abilities.
Reply by ●March 21, 20102010-03-21
On Sat, 20 Mar 2010 18:55:17 -0700 (PDT), a7yvm109gf5d1@netzero.com wrote:>On Mar 20, 8:23�pm, "k...@att.bizzzzzzzzzzzz" ><k...@att.bizzzzzzzzzzzz> wrote: >> On Sat, 20 Mar 2010 17:28:11 -0700 (PDT), whit3rd <whit...@gmail.com> wrote: >> >On Mar 20, 7:33�am, GreenXenon <glucege...@gmail.com> wrote: >> >> >> I keep hearing about Universal Serial Bus [USB]. Why hasn't a >> >> Universal Parallel Bus [UPB] been implemented yet? >> >> >It has been done, twice. �IEEE-488 for instruments, and SCSI >> >for small computers. >> >> >Expensive cables made IEEE-488 a boutique item, and SCSI >> >(which got up to 320 MBytes/sec) was usually kinda high-end >> >Most Macintosh computers from 1986 to 1998 used SCSI. >> >> >Parallel ports DO NOT COUNT, because they aren't a bus; >> >the early ones weren't even bidirectional, and there was >> >never any good support for more than two connections. >> >> Nonsense. �You could attach anything you wanted to them. �The parallel port on >> the PC has always been bidirectional. > >Nope. >http://en.wikipedia.org/wiki/Parallel_portHoisted by your own petard: In early parallel ports the data lines were unidirectional (data out only) so it was not easily possible to feed data in to the computer. However, a workaround was possible by using 4 of the 5 status lines. A circuit could be constructed to split each 8-bit byte into two 4-bit nibbles which were fed in sequentially through the status lines. Each pair of nibbles was then re-combined into an 8-bit byte. This same method (with the splitting and recombining done in software) was also used to transfer data between PCs using a laplink cable. i.e. bidirectional. The 8255 *was* bidirectional.>> >> >Bus, from 'omnibus' meaning 'for everyone' implies that all >> >bus signals are served by all devices, not just two. >> >> ALL devices? �My PCI bus doesn't serve my memory. �You're just making things >> up now. >So are you.IKWYABWAI is just SUCH a convincing argument. What a maroon!
Reply by ●March 21, 20102010-03-21
On 3/20/2010 9:23 PM, krw@att.bizzzzzzzzzzzz wrote:> On Sat, 20 Mar 2010 17:28:11 -0700 (PDT), whit3rd<whit3rd@gmail.com> wrote: > >> On Mar 20, 7:33 am, GreenXenon<glucege...@gmail.com> wrote: >> >>> I keep hearing about Universal Serial Bus [USB]. Why hasn't a >>> Universal Parallel Bus [UPB] been implemented yet? >> >> It has been done, twice. IEEE-488 for instruments, and SCSI >> for small computers. >> >> Expensive cables made IEEE-488 a boutique item, and SCSI >> (which got up to 320 MBytes/sec) was usually kinda high-end >> Most Macintosh computers from 1986 to 1998 used SCSI. >> >> Parallel ports DO NOT COUNT, because they aren't a bus; >> the early ones weren't even bidirectional, and there was >> never any good support for more than two connections. > > Nonsense. You could attach anything you wanted to them. The parallel port on > the PC has always been bidirectional. >No. It originated with the Monochrome Display/Parallel Port card for the PC, which was hardwired at I/O address 0x3bc. (Later versions had jumpers so you could move it to 0x378). It could be modded to run bidirectionally--I've done several--but it was unidirectional to start with. Later parallel port hardware, especially mobo parallel ports, usually used 0x378 or 0x278 (originally LPT2: and LPT3) to avoid conflicts with the monochrome/parallel card. The old LapLink parallel file sharing software used the data lines to talk in one direction and the control lines in the other. Cheers Phil Hobbs>> Bus, from 'omnibus' meaning 'for everyone' implies that all >> bus signals are served by all devices, not just two. > > ALL devices? My PCI bus doesn't serve my memory. You're just making things > up now.-- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●March 21, 20102010-03-21
On Sun, 21 Mar 2010 14:15:08 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 3/20/2010 9:23 PM, krw@att.bizzzzzzzzzzzz wrote: >> On Sat, 20 Mar 2010 17:28:11 -0700 (PDT), whit3rd<whit3rd@gmail.com> wrote: >> >>> On Mar 20, 7:33 am, GreenXenon<glucege...@gmail.com> wrote: >>> >>>> I keep hearing about Universal Serial Bus [USB]. Why hasn't a >>>> Universal Parallel Bus [UPB] been implemented yet? >>> >>> It has been done, twice. IEEE-488 for instruments, and SCSI >>> for small computers. >>> >>> Expensive cables made IEEE-488 a boutique item, and SCSI >>> (which got up to 320 MBytes/sec) was usually kinda high-end >>> Most Macintosh computers from 1986 to 1998 used SCSI. >>> >>> Parallel ports DO NOT COUNT, because they aren't a bus; >>> the early ones weren't even bidirectional, and there was >>> never any good support for more than two connections. >> >> Nonsense. You could attach anything you wanted to them. The parallel port on >> the PC has always been bidirectional. >> > >No. It originated with the Monochrome Display/Parallel Port card for >the PC, which was hardwired at I/O address 0x3bc. (Later versions had >jumpers so you could move it to 0x378). It could be modded to run >bidirectionally--I've done several--but it was unidirectional to start >with. Later parallel port hardware, especially mobo parallel ports, >usually used 0x378 or 0x278 (originally LPT2: and LPT3) to avoid >conflicts with the monochrome/parallel card. > >The old LapLink parallel file sharing software used the data lines to >talk in one direction and the control lines in the other.The PC-AT in '84 was bidirectional in the sense that there was a '245 or like to read output data pins, but no output disable on the on the output data latch/driver. I had the PC-AT technical manual with circuits, been a while since I read it though. So if you wrote all ones to port, you could read 8 bit input, providing external device was TTL logic that sinks many times the high level output current. IOW, TTL can be active low wire ORed. The nybble r/w method is far more reliable for any type of parallel port. Grant.
Reply by ●March 21, 20102010-03-21
<krw@att.bizzzzzzzzzzzz> wrote in message news:3clcq552ic5jonnrut4n2g7ejp6hn8lg4u@4ax.com...>>> Nonsense. You could attach anything you wanted to them. The parallel >>> port on >>> the PC has always been bidirectional. >> >>Nope. >>http://en.wikipedia.org/wiki/Parallel_port > > Hoisted by your own petard: > > In early parallel ports the data lines were unidirectional (data out > only) > so it was not easily possible to feed data in to the computer.Duh: the data lines were not bidirectional. I do not know of any other definition of "bidirectional" which allows different unidirectional wires to count as bidirectional. Bidirectional means two directions on the same wire (and in terms of implementation, usually two directions on the same port address, which certainly isn't true of the four status bits on the parallel port).> The 8255 *was* bidirectional.Still is. But they never used it. They used discrete latches, hence unidirectional. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
Reply by ●March 21, 20102010-03-21
On Sun, 21 Mar 2010 17:04:49 -0500, "Tim Williams" <tmoranwms@charter.net> wrote:><krw@att.bizzzzzzzzzzzz> wrote in message >news:3clcq552ic5jonnrut4n2g7ejp6hn8lg4u@4ax.com... >>>> Nonsense. You could attach anything you wanted to them. The parallel >>>> port on >>>> the PC has always been bidirectional. >>> >>>Nope. >>>http://en.wikipedia.org/wiki/Parallel_port >> >> Hoisted by your own petard: >> >> In early parallel ports the data lines were unidirectional (data out >> only) >> so it was not easily possible to feed data in to the computer. > >Duh: the data lines were not bidirectional.Bullshit. The Monochrome and printer adapter pinout: Pin No Signal Direction Register-bit DB25 Name 1 nStrobe Out Control-0 2 Data0 In/Out Data-0 3 Data1 In/Out Data-1 4 Data2 In/Out Data-2 5 Data3 In/Out Data-3 6 Data4 In/Out Data-4 7 Data5 In/Out Data-5 8 Data6 In/Out Data-6 9 Data7 In/Out Data-7 10 nAck In Status-6 11 Busy In Status-7 12 Paper-Out In Status-5 13 Select In Status-4 14 Linefeed Out Control-1 15 nError In Status-3 16 nInitialize Out Control-2 17 nSelect Out Control-3 18-25 Ground>I do not know of any other definition of "bidirectional" which allows >different unidirectional wires to count as bidirectional. Bidirectional >means two directions on the same wire (and in terms of implementation, >usually two directions on the same port address, which certainly isn't true >of the four status bits on the parallel port). > >> The 8255 *was* bidirectional. > >Still is. But they never used it. They used discrete latches, hence >unidirectional.
Reply by ●March 22, 20102010-03-22
Spehro Pefhany wrote:> On Sun, 21 Mar 2010 13:07:01 -0800, the renowned Robert Baer > <robertbaer@localnet.com> wrote: > >> whit3rd wrote: >>> On Mar 20, 7:33 am, GreenXenon <glucege...@gmail.com> wrote: >>> >>>> I keep hearing about Universal Serial Bus [USB]. Why hasn't a >>>> Universal Parallel Bus [UPB] been implemented yet? >>> It has been done, twice. IEEE-488 for instruments, and SCSI >>> for small computers. >>> >>> Expensive cables made IEEE-488 a boutique item, and SCSI >>> (which got up to 320 MBytes/sec) was usually kinda high-end >>> Most Macintosh computers from 1986 to 1998 used SCSI. >>> >>> Parallel ports DO NOT COUNT, because they aren't a bus; >>> the early ones weren't even bidirectional, and there was >>> never any good support for more than two connections. >>> Bus, from 'omnibus' meaning 'for everyone' implies that all >>> bus signals are served by all devices, not just two. >> Well, it turns out that the ORIGINAL PC/XT in 1980 had all of the >> hardware on board to do full 8-bit I/O. >> Are you perhaps alluding to an earlier version?? > > You sure about that? I recall that inputs had to be done 4 bits at a > time (nibble mode) to assure compatibility. I have a chunk of code > around somewhere that defines all the printer control signals in a > sensible way for general purpose control (some are inverted IIRC...) > > Checking Jan Axelson's seminal publication "Parallel Port Complete", I > see she says:- > > The original PC's parallel port had eight outputs, five inputs, and > four bidirectional lines.... On many newer PCs, the eight oututs can > also serve as inputs..." > > Now, the really crotchety old farts will remember that there was a > hardware modification you could do to the original parallel port cards > (wot used LS TTL parts) to cut the /ENABLE pin of the output latch so > it wasn't permanently grounded, and jumper it to allow it to be > controlled for birectional I/O, but I wouldn't claim that this "had > all the hardware on board" when soldering irons and dremels are > involved... > > Of course all this stuff has been in a corner of an LSI chip for > decades now, so you're stuck with whatever IP is used for the chip, > but you used to be able to do it. > > > > Best regards, > Spehro PefhanyWell, include me as one of those crotchety old farts that did the mod _without_ the use of a dremel tool (am a bit sneaky at times, then being a new dog at old tricks). The hardware was there, only a slight improvement was needed...
Reply by ●March 22, 20102010-03-22
MooseFET wrote:> On Mar 21, 2:07 pm, Robert Baer <robertb...@localnet.com> wrote: >> whit3rd wrote: >>> On Mar 20, 7:33 am, GreenXenon <glucege...@gmail.com> wrote: >>>> I keep hearing about Universal Serial Bus [USB]. Why hasn't a >>>> Universal Parallel Bus [UPB] been implemented yet? >>> It has been done, twice. IEEE-488 for instruments, and SCSI >>> for small computers. >>> Expensive cables made IEEE-488 a boutique item, and SCSI >>> (which got up to 320 MBytes/sec) was usually kinda high-end >>> Most Macintosh computers from 1986 to 1998 used SCSI. >>> Parallel ports DO NOT COUNT, because they aren't a bus; >>> the early ones weren't even bidirectional, and there was >>> never any good support for more than two connections. >>> Bus, from 'omnibus' meaning 'for everyone' implies that all >>> bus signals are served by all devices, not just two. >> Well, it turns out that the ORIGINAL PC/XT in 1980 had all of the >> hardware on board to do full 8-bit I/O. >> Are you perhaps alluding to an earlier version?? > > The "standard" PC printer port of the PC/XT was the 8255. > This chip could go both directions. Later PCs integrated the > printer port function into a chip and removed some of the > abilities. >Nope; IBM Technical Reference Manual, First Edition, August 1981 on page D-34 clearly shows a LS374 for data out, and a LS244 for data in.
