jbjones@marlin.NOSC.MIL (John B. Jones) (09/07/89)
>| ACER 386/20 MotherBd AT Jr. Anyone familiar with this? > Look for another motherboard which allows use of DIP instead. There >are a few which take up to 4MB DIP *and* 4 MB SIMM. Please, a few morsels for the ignorant... What is a SIMM? What is DIP? What is the difference between these two? Go ahead and post, I guess; it would probably be beneficial to the group at large. Thanks for explanations. jbjones jbjones@marlin.nosc.mil
davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr) (09/08/89)
In article <1214@marlin.NOSC.MIL>, jbjones@marlin.NOSC.MIL (John B. Jones) writes: | Please, a few morsels for the ignorant... | | What is a SIMM? What is DIP? What is the difference between these two? | Go ahead and post, I guess; it would probably be beneficial to the group | at large. Thanks for explanations. Since I mentioned it, here's what I meant: the SIMM is a Single Inline Memory Module. What that means is that it is a component which is high and narrow, and has a single line of connectors on the bottom. A DIP is a Dual Inline Package, which looks like a typical "chip," having a row of pins down each side of the chip. The SIMM saves board real estate while the DIP is cheaper. I suspect that the cost of making them is about the same, per MB, but that the chip makers feel the SIMM is "better" and charge a lot more for it. Note that I don't state this reason as a fact. DIPs are 1 bit wide, so for a 16 bit computer you need at least 18 (16 bits plus parity), while SIMMS can be made wider, in 8 bit (no parity, for Macs and system which don't bother to check errors) and 9 bit (for PC types). ________________________________________________________________ | | | Going on vacation... be back 9/18 or 9/25 weather permitting | | Replies will be delayed. | |________________________________________________________________| -- bill davidsen (davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen) "The world is filled with fools. They blindly follow their so-called 'reason' in the face of the church and common sense. Any fool can see that the world is flat!" - anon
silver@eniac.seas.upenn.edu (Andy Silverman) (09/08/89)
In article <307@crdos1.crd.ge.COM> davidsen@crdos1.UUCP (bill davidsen) writes: >DIPs are 1 bit wide, so for a >16 bit computer you need at least 18 (16 bits plus parity), while SIMMS >can be made wider, in 8 bit (no parity, for Macs and system which don't >bother to check errors) and 9 bit (for PC types). Correct me if I'm wrong, but the number of bits wide a given chip is entirely up to the chip designers, and is not a function in any way of the packaging involved. You can get DIP-packaged memory chips in 1, 4, and probably 8 bits wide, it's just that the most popular memory chips (say for memory expansion of your generic PC) are the 1 bit wide variety. SIMMs are generally just 9 surface mounted 1 bit wide memory chips on a small board which mounts vertically in a slot designed specially for it. +-----------------------+-----------------------------------------+ | Andy Silverman | Internet: silver@eniac.seas.upenn.edu | | "All stressed out and | Compu$erve: 72261,531 | | nobody to choke." | | +-----------------------+-----------------------------------------+
ray@philmtl.philips.ca (Raymond Dunn) (09/13/89)
In article <307@crdos1.crd.ge.COM> davidsen@crdos1.UUCP (bill davidsen) writes: >DIPs are 1 bit wide, so for a........ In article <14155@netnews.upenn.edu> silver@eniac.seas.upenn.edu.UUCP (Andy Silverman) responds: >Correct me if I'm wrong, but the number of bits wide a given chip is entirely >up to the chip designers.... >You can get DIP-packaged memory chips in 1, 4, and probably 8 >bits wide So far so good..... >SIMMs are generally >just 9 surface mounted 1 bit wide memory chips on a small board which mounts >vertically in a slot designed specially for it. Now you fall into the same trap your response is correcting. SIMMs can and do commonly contain any format of chips, 1, 4 and 8 bits wide, even _mixtures_ (often to produce 9 bit wide SIMMS commonly used on PC's for 8 bits plus parity). On the original question of cost, SIMMS are more expensive than DIP chips because SIMMS are made from DIPS mounted on a small PC board with connector fingers. The cost of the board and the mounting of the chips is obviously going to produce a cost increment over that of the individual chips, even when compared to a single chip with the same number of bits as that on the SIMM. -- Ray Dunn. | UUCP: ..!uunet!philmtl!ray Philips Electronics Ltd. | TEL : (514) 744-8200 Ext: 2347 600 Dr Frederik Philips Blvd | FAX : (514) 744-6455 St Laurent. Quebec. H4M 2S9 | TLX : 05-824090
davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr) (09/19/89)
In article <701@philmtl.philips.ca>, ray@philmtl.philips.ca (Raymond Dunn) writes: | In article <307@crdos1.crd.ge.COM> davidsen@crdos1.UUCP (bill davidsen) writes: | >DIPs are 1 bit wide, so for a........ | | In article <14155@netnews.upenn.edu> silver@eniac.seas.upenn.edu.UUCP (Andy Silverman) responds: | >Correct me if I'm wrong, but the number of bits wide a given chip is entirely | >up to the chip designers.... You're obviously correct, but if a vendor wants to sell a chip, it had better either be what the market expects or something very much better. In the case of DIPs, the standard has been 1 bit for large sizes, with some items also available in 4 bit. I often wondered if there would be a markey for a four byte wide chip with ECC on the chip, and two status pins coming out for "soft error" and "hard error." Because of the way most ECC works, it is cheaper to do ECC on more bits wide, since schemes like Hamming take log2N+1 bits for the correction data (6 bits of ECC data for 32 bits of "normal" data). -- bill davidsen (davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen) "The world is filled with fools. They blindly follow their so-called 'reason' in the face of the church and common sense. Any fool can see that the world is flat!" - anon