--------------- FIDO MESSAGE AREA==> TOPIC: 145 ASSEMBLY LANG. Ref: F1Y00000Date: 01/28/98 From: ADAM MAJER Time: 01:05pm \/To: JEFF QUINDLEN (Read 0 times) Subj: Interrupts JQ> Okay, I know that the first 1024 bytes contain the interrupt vector JQ>table, and the interrupt vector table points to addresses in memory for each JQ>interrupt. I was wondering this, how does an interrupt really work? More JQ>specificly, what does the contents of each segment:offset in the interrupt JQ>vector table point to? Could I simply edit the interrupt vector table to JQ>point to my own .COM file in memory, or is it accomplished differently. You can do that but make sure that that com file stays in memory or it hit Mr.Reset again! * SLMR 2.1a * I'm in shape ... round's a shape isn't it? --- FMail 0.92 * Origin: The Programmer's Oasis on FIDONET! (1:348/203) --------------- FIDO MESSAGE AREA==> TOPIC: 145 ASSEMBLY LANG. Ref: F1Y00001Date: 01/28/98 From: SCOTT MCNAY Time: 09:56am \/To: SAM IZZO (Read 0 times) Subj: Year2000 problem *** Sam Izzo wrote in a message to All: SI> Hmm.. I always thought that generally speaking, PCs were SI> fine when it came to the so-called Year 2000 problem. SI> However, while perusing the CMOS memory map that comes with SI> Ralf Brown's interrupt listing, I noticed it said that the SI> year in the CMOS is stored as a BCD ranging from 00 to 99. SI> Has this been fixed in more recent CMOSs, or are they all SI> like this? I figured they would all have to be like that, SI> because otherwise Ralf would've had it in his list. SI> It would seem, then, that most PCs, even up to this day, SI> have a problem. Of course, I could be completely wrong. Can SI> anyone shed some light on all of this? There's an entire echo on the subject, the area name is 2000. Most BIOSes up to maybe a year ago are NOT compatible, it seems. And the BIOS in a computer is usually a bit older than the computer itself, so even if you have a brand new computer, it may not be compatible. --Scott. --- timEd 1.01 * Origin: Wizard's PC Services, BBS=254-554-2146, Pager=903-3097 (1:395/11) --------------- FIDO MESSAGE AREA==> TOPIC: 145 ASSEMBLY LANG. Ref: F1Y00002Date: 01/27/98 From: GLEN MCNABB Time: 07:53pm \/To: JEFF QUINDLEN (Read 0 times) Subj: Interrupts Hi Jeff, On <26 Jan, 13:02>, Jeff Quindlen wrote to All : JQ> Okay, I know that the first 1024 bytes contain the interrupt vector JQ> table, and the interrupt vector table points to addresses in memory for JQ> each interrupt. I was wondering this, how does an interrupt really work? JQ> More specificly, what does the contents of each segment:offset in the JQ> interrupt vector table point to? Could I simply edit the interrupt JQ> vector table to point to my own .COM file in memory, or is it JQ> accomplished differently. Simply put, depending on the type of interupt, either software or hardware, the processor pushes the flags, CS, and IP registers (in that order), then it clears the interupt enable and single trace flags. Once this is done, it fetches the address of the "interupt handler" located on the interupt vector table and begins execution of instructions there. It usually requires an IRET instruction to return... Yes, it is quite possible to change addresses in the interupt vector table. You should clear the interupt enable flag prior to doing this so that an interupt doesn't occur during this process. If you use MSDOS you can use int 21h function 35h to get interupt vector and int 21h function 25h to set an interupt vector. A typical interupt to change is int 23h, the Ctrl-C vector. Changing this vector to just a IRET instruction prevents anyone from control- breaking out of a program. The nice part about changing this vector is that you don't have to change it back. MSDOS restores this vector when a program exits. (nice huh?) Glen. --- ProBoard v2.16 [Reg] * Origin: NC/NEC SEWAnet, Bucolic Fair (1:3407/25) --------------- FIDO MESSAGE AREA==> TOPIC: 145 ASSEMBLY LANG. Ref: F1Y00003Date: 01/27/98 From: GLEN MCNABB Time: 07:57pm \/To: SAM IZZO (Read 0 times) Subj: Year2000 problem On <26 Jan, 00:10>, Sam Izzo wrote to All : SI> I decided to write a test program which displayed the date/time according SI> to SI> the CMOS and the date/time according to the DOS interrupts, and set them SI> to SI> just before 1/1/2000 and let them both tick over. Of course, the CMOS SI> said SI> 1/1/00, and the day of week was Monday, which is incorrect, as it should SI> be a SI> Saturday. The Monday would've been correct if it was 1/1/1900 though. SI> The DOS SI> interrupts had the correct information, including the year. I rebooted, SI> ran the SI> program again, and DOS still reported 2000. How did DOS get the year as SI> 2000 SI> when in the CMOS it said 00?? Oh, and the CMOS setup said 2000. SI> It would seem, then, that most PCs, even up to this day, have a problem. SI> Of SI> course, I could be completely wrong. Can anyone shed some light on all of SI> this? The simplest answer would be that... Only XT user's know that Jan 1st, 1980 was a Tuesday. Try setting your DOS date to prior to 1980 and see what happens... Glen. --- ProBoard v2.16 [Reg] * Origin: NC/NEC SEWAnet, Bucolic Fair (1:3407/25) --------------- FIDO MESSAGE AREA==> TOPIC: 145 ASSEMBLY LANG. Ref: F1Y00004Date: 01/28/98 From: JANIS KRACHT Time: 09:18am \/To: ALL (Read 0 times) Subj: New PDN files at < TOPIC: 145 ASSEMBLY LANG. Ref: F1Y00005Date: 01/28/98 From: DARRYL GREGORASH Time: 08:50am \/To: SCOTT MCNAY (Read 0 times) Subj: Directly writing to memor Replying to a message of Scott McNay to Darryl Gregorash: DG>> mov ss:[sp], eax DG>> sub sp,4 SM> Shouldn't that be the other way around? I don't think so; it mimics a PUSH. SM> (assuming, of course, that mov ax,ss:[sp] worked ;) Why wouldn't it? --- FleetStreet 1.21 NR * Origin: BIG BANG Burger Bar: Regina SK Canada (1:140/86) --------------- FIDO MESSAGE AREA==> TOPIC: 145 ASSEMBLY LANG. Ref: F1Y00006Date: 01/25/98 From: HIDASI JOZSEF Time: 08:04pm \/To: PETER MAGNUSSON (Read 0 times) Subj: himem source code Hi Peter/All! PM> If you read what I said, afaik no sources have been PM> released. I've a big probelm: I would like to access the memory >1Mb, but there's no HIMemory handler in the memory... So Could you help me a short source how to read it? Do I have to use Protected Mode for it??? E-Mail: Hidasi.Jozsef@MTTBBS.hu Hidi... --- FMail/386 1.22 * Origin: Earth - Europe - Hungary - Budapest - SnowBoard BBS (2:371/17) --------------- FIDO MESSAGE AREA==> TOPIC: 145 ASSEMBLY LANG. Ref: F1Y00007Date: 01/28/98 From: ED BEROSET Time: 03:53pm \/To: ALL (Read 0 times) Subj: Re: Moderator election From: Ed Beroset Subject: Re: Moderator election Darryl Gregorash wrote: > > Replying to a message of James Vahn to Darryl Gregorash: > > JV>>> The BOFAQ is for the most part a Moderators FAQ and some > JV>>> technical standards. > >> > >> No, it isn't. It is published by John Souvestre, et al. [...] > > Do note that it also describes itself as a set of FAQs for "the" backbone, > implying that the NAB is the only game in town. Most of the definitions ave > been reworded from their original forms, which definitely tried to give hat > mis-impression. Maybe you should write a better, more neutral one. FWIW, I'll bet that those of us who don't give a fig about Fidonet politics would neither notice nor be influenced by such subtleties. I wouldn't lose too much sleep over it if I were you -- I'm sure James is just looking for some written info describing what a moderator does, and is probably not plotting to take over the world. If that were his aim, this would be a mighty strange place to start. ;-) Ed -!- --- * Origin: The Circuit! Board * Spokane * (1:346/100)