seb3@GTE.COM (Steve Belczyk) (12/04/90)
Hi there! I have a few dumb questions about Minix for the IBM:
-- The Minix information sheet mentions that the IBM Minix supports
up to three simultaneous users. Is there any way to add two more,
on COM3 and COM4?
-- The information sheet also makes no mention of VGA. Will I be able
to use Minix with a VGA card?
-- How difficult is it to get UUCP and News running under Minix?
-- The machine I'm considering is a Gateway 2000 386/25 with an IDE
drive. I would love to hear from anyone who has used Minix on such
a machine.
Thank you very much.
Steve Belczyk CIS: 75126,515 BBS: +1 508 664-0149 (2400 bps)
seb3@gte.com GEnie: sbelczyk UUCP: {harvard,vaxine}!bunny!seb3ghelmer@dsuvax.uucp (Guy Helmer) (12/04/90)
In <10150@bunny.GTE.COM> seb3@GTE.COM (Steve Belczyk) writes: >Hi there! I have a few dumb questions about Minix for the IBM: >-- The Minix information sheet mentions that the IBM Minix supports > up to three simultaneous users. Is there any way to add two more, > on COM3 and COM4? Not really. There aren't enough interrupt request lines available in a PC to let COM3 and COM4 have their own interrupts, so they have to share interrupts with COM1 and COM2. It would be quite a challenge to change the rs232 driver to handle shared interrupt lines, and the additional interrupt service overhead would eat up even more CPU cycles than it does now :-( It would be a much better idea to get a smart multi-port rs232 adapter card and try to either 1) find a driver for it or 2) write a driver if you really want to support four or five users. >-- The information sheet also makes no mention of VGA. Will I be able > to use Minix with a VGA card? Mine works! :-) >-- How difficult is it to get UUCP and News running under Minix? It's not very difficult. I had uucp and mail running in a couple hour's time. >Steve Belczyk CIS: 75126,515 BBS: +1 508 664-0149 (2400 bps) -- Guy Helmer helmer@sdnet.bitnet, uunet!dsuvax!ghelmer work: DSU Computing Services, Business & Education Institute (605) 256-5315 play: MidIX System Support Services (605) 256-2788 postnews: message content ambiguous; spurious information added as required
cgs@umd5.umd.edu (Chris G. Sylvain) (12/05/90)
In article <1990Dec4.151849.28931@dsuvax.uucp> ghelmer@dsuvax.uucp (Guy Helmer) writes: >In <10150@bunny.GTE.COM> seb3@GTE.COM (Steve Belczyk) writes: > > >> [..] Is there any way to add two more, on COM3 and COM4? > >Not really. [..] It would be quite a challenge to change the rs232 driver >to handle shared interrupt lines, and the additional interrupt service >overhead would eat up even more CPU cycles than it does now :-( Sorry Guy, but I think it would be much less of a deal than you indicate. All the rs232 driver needs to do is read two IIR (interrupt identification registers) instead of one. Both IIRs may indicate an interrupt pending, in which case you receive (or transmit) two characters for the price of one interrupt. Is that really so terrible? Worst valid case is when the interrupt was not posted by the first IIR read. The second is read instead, and a different tty minor number is used to move a character (or begin moving a buffer-full). I'm not convinced that an unacceptable amount of byte shoveling is needed to read a second IIR and stuff a byte (or yank a byte) from the appropriate tty_nr->buffer. Worst case is when neither IIR shows a pending interrupt. The cost of supporting the shared interrupt was the (small) time required to read the second IIR. Thoughts anyone? (or am I about to be flamed?) -- --==---==---==-- Mome: Short for _from home_ - meaning you've lost your way -- ARPA: cgs@umd5.UMD.EDU BITNET: cgs%umd5@umd2 -- -- UUCP: ..!uunet!umd5.umd.edu!cgs --
ghelmer@dsuvax.uucp (Guy Helmer) (12/05/90)
In <7668@umd5.umd.edu> cgs@umd5.umd.edu (Chris G. Sylvain) writes: >In article <1990Dec4.151849.28931@dsuvax.uucp> ghelmer@dsuvax.uucp (Guy Helmer) writes: >>In <10150@bunny.GTE.COM> seb3@GTE.COM (Steve Belczyk) writes: >> >> >>> [..] Is there any way to add two more, on COM3 and COM4? >> >>Not really. [..] It would be quite a challenge to change the rs232 driver >>to handle shared interrupt lines, and the additional interrupt service >>overhead would eat up even more CPU cycles than it does now :-( >Sorry Guy, but I think it would be much less of a deal than you indicate. >All the rs232 driver needs to do is read two IIR (interrupt identification >registers) instead of one. Yes, that's right. I goofed, since I never bothered to think about how to actually handle a shared interrupt configuration. -- Guy Helmer helmer@sdnet.bitnet, uunet!dsuvax!ghelmer work: DSU Computing Services, Business & Education Institute (605) 256-5315 play: MidIX System Support Services (605) 256-2788 postnews: message content ambiguous; spurious information added as required
jca@pnet01.cts.com (John C. Archambeau) (12/06/90)
ghelmer@dsuvax.uucp (Guy Helmer) writes: >Not really. There aren't enough interrupt request lines available >in a PC to let COM3 and COM4 have their own interrupts, so they >have to share interrupts with COM1 and COM2. It would be quite >a challenge to change the rs232 driver to handle shared interrupt >lines, and the additional interrupt service overhead would eat >up even more CPU cycles than it does now :-( Not really. You could set up the RS-232 driver to follow the COM1-COM4 conventions of the PS/2. They are as follows: Base Name Address IRQ ----------------------- COM1 0x3f8 4 COM2 0x2f8 3 COM3 0x3e8 5 COM4 0x2e8 2 The only problem with that is you have to steal IRQ 5 from one of your parallel ports (if you have more than one) and give it to COM3. If you have a bus mouse or 8-bit networking adaptor, that usually uses IRQ 2, so you'll have to steal IRQ 2 from that device. >It would be a much better idea to get a smart multi-port rs232 adapter >card and try to either 1) find a driver for it or 2) write a driver >if you really want to support four or five users. >hour's time. Or modify the FAS driver to work under Minix. I don't know if it will perform as well giving you the 38.4K baud with hardware handshaking under Minix. Anyone who has an AST 4 Port AT/Plus may want to try it. The driver as is works with that board so minimal modification would have to be done to get it to work under Minix. // JCA /* **--------------------------------------------------------------------------* ** Flames : /dev/null | What to buy? ** ARPANET : crash!pnet01!jca@nosc.mil | EISA or MCA? ** INTERNET: jca@pnet01.cts.com | When will the bus wars end? ** UUCP : {nosc ucsd hplabs!hp-sdd}!crash!pnet01!jca **--------------------------------------------------------------------------* */
adrie@philica.ica.philips.nl (Adrie Koolen) (12/07/90)
In article <6113@crash.cts.com> jca@pnet01.cts.com (John C. Archambeau) writes: >Not really. You could set up the RS-232 driver to follow the COM1-COM4 >conventions of the PS/2. They are as follows: > > Base >Name Address IRQ >----------------------- >COM1 0x3f8 4 >COM2 0x2f8 3 >COM3 0x3e8 5 >COM4 0x2e8 2 The IBM PS/2 Model 60 I worked with, had two standard RS232 channels. The first one used IRQ 4, the second one IRQ 3. I had an extra micro-channel card with one RS232 channel. It also used IRQ 3 (interrupt sharing is standard on the micro-channel as it uses level sensitive interrupts). The documentation stated that all additional IBM RS232 channels use IRQ 3. Adrie Koolen (adrie@ica.philips.nl) Philips Innovation Centre Aachen
jca@pnet01.cts.com (John C. Archambeau) (12/10/90)
adrie@philica.ica.philips.nl (Adrie Koolen) writes: >The IBM PS/2 Model 60 I worked with, had two standard RS232 channels. The first >one used IRQ 4, the second one IRQ 3. I had an extra micro-channel card with >one RS232 channel. It also used IRQ 3 (interrupt sharing is standard on the >micro-channel as it uses level sensitive interrupts). The documentation stated >that all additional IBM RS232 channels use IRQ 3. My information on the PS/2 conventions is second hand knowledge. It was given to me via an article on adding COM3 and COM4 to SCO Xenix. This may apply to only the ISA PS/2 models, in which case it would apply to Minix since there is no MCA support for Minix (or was that added under my nose? :) ). // JCA /* **--------------------------------------------------------------------------* ** Flames : /dev/null | What to buy? ** ARPANET : crash!pnet01!jca@nosc.mil | EISA or MCA? ** INTERNET: jca@pnet01.cts.com | When will the bus wars end? ** UUCP : {nosc ucsd hplabs!hp-sdd}!crash!pnet01!jca **--------------------------------------------------------------------------* */