Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!rutgers!mtune!codas!usfvax2!tscs!gerard From: gerard@tscs.UUCP Newsgroups: comp.sys.ibm.pc Subject: Re: Intel Microprocessors Message-ID: <138@tscs.UUCP> Date: Tue, 18-Aug-87 02:46:39 EDT Article-I.D.: tscs.138 Posted: Tue Aug 18 02:46:39 1987 Date-Received: Thu, 20-Aug-87 01:23:46 EDT References: <1112@lznv.ATT.COM> <399@aucs.UUCP> <3225@cucca.columbia.edu> <789@unccvax.UUCP> <1924@Shasta.STANFORD.EDU> Reply-To: gerard@tscs.UUCP (system administrator) Distribution: world Organization: Total Support Computer Systems, Tampa, Florida Lines: 75 In article <1924@Shasta.STANFORD.EDU> tang@Shasta.STANFORD.EDU (Kit Tang) writes: >>> make use of their opportunity to escape from the Intel tar pit >>> and use the MC68020 to make the PS/2 into a REAL computer? >> > >> One final note, the 386 has a 1meg segment limit. What a limit. > ^ 4G (I think) > Yes, one segment in the 386 is the same as the whole 68020. > >> What size segmentation would you like? > The current virtual address space the 386 can address is 64T, but > the huge address space has to be accessed through segment (4G max). > How about a single segment of 64T ? Yes, the 80386 has up to 4 Gigabytes of physical RAM, and 64 Terabytes of virtual address space. I don't think 4 Gigabytes the limiting factor here! How many memory chips is 4 Gigabytes anyway? Chip Size 64Kx1 256Kx1 1024Kx1 # Required 524,288 131,072 32,768 Note: This does not include parity or ECC. If 256K chips were $1.75 each (Cheap) and the board and support logic was free, that would be: $225,376.00 (hardly micro costs) If it took only 5 seconds to install each chip: It would take 7.6 days of continous work to install 131,072 256K chips. If a disk drive was large enough and transfered data at a rate of 1.25M bytes/second (maximum xfer rate of SMD or ESDI drives), and you were the only process on that drive: 55 minutes transfer time for 4 Gigabytes. I could see the message "core dumped - go to lunch", or on a system with other users, "core dumped - come back tommorrow" :-). Stacked on top of each other, a stack of 131,072 - 256K chips would be 1,547 feet 4.5 inches or .29 miles high. (not counting pins) 131,072 - 256K chips in sockets would occupy 327.6 square feet of board space or 864 IBM AT sized PC boards. (no support circuitry) The power supply for 131,072 - 256K RAMs would require a 5 volt supply capable of between 39,322 and 131,072 watts. Not to mention how much air conditioning would be required to keep it cool. By the way, anyone have 64+ Terabytes of swap space? Not to sell 4G physical, and 64T virtual address space short, it is nice to have limits that are extremely high. This might make you think you have no limits at all! I think we need higher density RAM's and larger/faster disk storage devices before we could even think of reaching 4G of main memory. Yes, an on-chip MMU does reduce the chip count, nice for the engineer. A programmer on the other hand would welcome an additional 8 thirtytwo bit registers. Yes, the MC68020 has twice the number of 32 bit general purpose registers as the 80386. If you consider the usage of the registers on each machine, the 68020 come out further ahead. The 68020 also has 4 Gigabytes of physical address space. The MC68030 does have a built-in MMU. For a good laugh, you might like to read a Motorola publication entitled "Motorola MC68020 Benchmark Report" (Publication BR322). It is interesting to see how Intel cheated on some of it's benchmarks against Motorola chips. I wouldn't want to buy a used car from Intel :-). I tend to believe Motorola's claims, as if they were false, the lawyers at Intel would have a field day. Also included in this report, are the listings of the benchmark programs. At least the 68020 can multiply 32 bit numbers :-). ------------------------------------------------------------------------------ Stephen Gerard - Total Support Computer Systems - Tampa - (813) 876-5990 UUCP: ...{codas, gatech}!usfvax2!tscs!gerard US-MAIL: Post Office Box 15395 - Tampa, Florida 33684-5395