Path: csiph.com!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: Peter 'Shaggy' Haywood Newsgroups: alt.os.linux,alt.comp.os.windows-11 Subject: Re: So far OT ..... DVD+R v DVD-R ... What's the difference?? Followup-To: alt.os.linux Date: Tue, 25 Feb 2025 12:28:24 +1100 Organization: A noiseless patient Spider Lines: 60 Message-ID: References: <2dhc8lxgq6.ln2@Telcontar.valinor> <67b8c8ac$0$22$882e4bbb@reader.netnews.com> <67ba2b89$2$1786$882e4bbb@reader.netnews.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7Bit Injection-Date: Tue, 25 Feb 2025 14:08:22 +0100 (CET) Injection-Info: dont-email.me; posting-host="7ae487b7d1a8e814478cd00713ea9be5"; logging-data="2096981"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/QV2sCTFEpsMHtzpgE11gQ01pcA12npF4=" User-Agent: KNode/0.10.9 Cancel-Lock: sha1:zfjxHmRT96U1GMzSWCZm9XhH5Rw= Xref: csiph.com alt.os.linux:81044 alt.comp.os.windows-11:17456 Groovy hepcat Mark Lloyd was jivin' in alt.os.linux on Sun, 23 Feb 2025 06:54 am. It's a cool scene! Dig it. > On Fri, 21 Feb 2025 19:30:50 +0000, Ant wrote: > >> In alt.comp.os.windows-11 Mark Lloyd wrote: >>> On Fri, 21 Feb 2025 12:11:53 +0100, Carlos E.R. wrote: >> >>> [snip] >> >>> > Yes, an optional separate coprocesor was used initially. If it was >>> > not inserted, an operation trying to use a coprocesor instruction >>> > would raise an exception, which would be attended and the >>> > instruction emulated in software by the program, which was >>> > significantly slower. >> >>> IIRC, the 286 was the first to have that exception, although there >>> were programs to emulate it on older systems. If I remember right, >>> the turbo C compiler would replace every floating point instruction >>> with a call to a routine that checked for a FPU. If it found one it >>> would replace that call with the FPU instruction and return to a few >>> bytes earlier to run that instruction, otherwise it would emulate >>> it. >> >>> [snip] >> >> What about 386SX? IIRC, it didn't have a coprocessor like DX. I can't >> remember! > > No 386 had a coprocessor. You could add a 387 to the system (I don't > remember if there was a 387SX). IIRC, it was also possible to use a > 287. Yes, there was a 387SX. And co-processors (or FPUs, as they're more correctly called) for PC family CPUs go right back to the 8087 to go with the 8086/8088. So a PC/XT could have an FPU too. > The difference between 386SX and 386DX was a limited (24-bit instead > of 32-bit) address bus, and a multiplexed (32-bit) data bus. For anyone who doesn't know what that means; the 386SX had a 16 bit data bus, the same as the 286. All 32 bit memory access instructions had to "thunk" between the internal 32 bit registers and the external data bus, meaning that a 32 bit memory access had to be done in two 16 bit accesses. > It was with the 486 that the DX meant it had a coprocessor. There was > also a 486DX2 that ran at a doubled clock speed. Right. There is also a 486DX4, which runs at 4 times the clock speed. And the 486SX had no built-in FPU, so there is a 487SX to go with it. -- ----- Dig the NEW and IMPROVED news sig!! ----- -------------- Shaggy was here! --------------- Ain't I'm a dawg!!