paj@gatech.UUCP (12/03/87)
I have a terminal emulator package that I have
written that is interrupt driven from the serial
port and it does not work on the PS/2 model 50
system (DOS 3.3) that I just got.
The program sets up the 8259 to enable
interrupts from the serial port. The 8259 used
to use IRQ4 for the serial port interrupt -
has this or the address of the 8259 port changed ?
Is there an 8259 port in the PS/2 Mod 50 system ?
Can anyone give me any suggestions as to what
may be causing me a problem or direct me to
documentation which describes the interrupts
for the PS/2 model 50 system and how to enable
them for the serial (com) port ?
Also, I am not using BIOS to read/write the serial port
since I need to be able to do things like send a BREAK
and ignore RTS/CTS interaction. The way this was done was
to map the BIOS data segment into my program and get the
RS_232 base address from the BIOS data area. Has the offset
to the RS_232 base address in the BIOS data area changed ?
Once again - Is there a manual that describes what I need to
know for the PS/2 model 50 system ?
Thanks,
P. Allen Jensen
--
P. Allen Jensen
GTICES Systems Laboratory, Civil Engineering, Georgia Tech, Atlanta GA 30332
CSNet: paj @ GATech ARPA: paj%GATech.CSNet @ CSNet-Relay.ARPA
uucp: ...!{akgua,allegra,amd,hplabs,ihnp4,seismo,ut-ngp}!gatech!pajmac3n@babbage.UUCP (12/05/87)
In article <16803@gatech.edu>, paj@gatech.edu (P. Allen Jensen) writes: > port and it does not work on the PS/2 model 50 > > The program sets up the 8259 to enable > interrupts from the serial port. The 8259 used The 8259 triggers interrupts off the IRQ lines either by edge or by level. In the PC it's edge, making it hard to share IRQ lines. I believe this changed to level in the PS/2.
wtm@neoucom.UUCP (Bill Mayhew) (12/07/87)
Just a few days ago, I has this question and talked to a knowledgable person as SCO. He confirmed that in the PS/2 level triggering is used. Just to keep life interesting, I suppose. I have the PS/2 BIOS manual, and don't recall seeing that documented, but them I haven't finished absorbing every single word there yet. He also mentioned relative to the model 80 that if a '387 fpu is installed that the system can hang totally if a lot of floating point is going on at the same time as a long DMA xfer (like to disk for instance). Intel has announced that this is indeed a bug with the '386 to '387 interface. Apparently it can be remedied by the addition of a few SSI gates on some control lines between the '386 and '387. How easy it would be to fix on a model 80, I don't know. I have used a model 80 owned by an associate that *does* have a '387 and have not yet seen the aforementioned bug. (knock on wood...) Unlike the other PS/2 models, I am impressed with the 80. It is a nicely assembled box. The 70 meg *IBM made* ESDI disk is quite a screamer too. Quite a nice product; now if I only had the $$$. One of the nicer aspects of the 80 is that it doesn't sound like a miniature wind tunnel next to the desk; in fact it is barely audible. --Bill
davidsen@steinmetz.steinmetz.UUCP (William E. Davidsen Jr) (12/09/87)
In article <132@babbage.acc.virginia.edu> mac3n@babbage.acc.virginia.edu (Alex Colvin) writes: | The 8259 triggers interrupts off the IRQ lines either by edge or by level. | In the PC it's edge, making it hard to share IRQ lines. | I believe this changed to level in the PS/2. I tried a number of communication programs, both internally written and other, and they ran on the PS/2. There is a bit in the 8259 which selects edge or level trigger, but it may be initialized diferently by the BIOS software (you do initialize everything, right?) in the PS/2. -- bill davidsen (wedu@ge-crd.arpa) {uunet | philabs | seismo}!steinmetz!crdos1!davidsen "Stupidity, like virtue, is its own reward" -me