18215MES@MSU.BITNET (08/23/89)
Yipes! $479.00 per 1 meg simm (sip?) I am a MAC person in an IBM world - We also are about to move our old pdp 1170 UNIX dbms to SCO XENIX, so we got a Zenith 33 megahertz pc w/ 320 meg hd and going to ethernet the office and eventually the building... Anyway, they called me over to show me one of the simms they got in, and it looked pretty strange... they are 80 nanosecond, 12 chips altogether on a simm board much like MAC simms, except that there were 6 chips on 2 rows, and the four chips in the middle of the bottom row were quite a bit smaller than the others... I asked how much they paid ( I think they got them from Zenith cause then they say they only have to deal with one vendor), and he said $479.00 !!! YIPES !!! So anyway, I looked in a PC week, and saw Zenith 386 simms (1 meg x 9) advertised for $299, and called, and asked about the 12 chips (vs the MAC's 8 or the 9 on IBM sips), and the salesman said that in fact the simm he had really had 12 chips on it... and couldn't explain what the smaller chips were for... DOES ANY ONE KNOW WHAT GIVES?? What are those extra chips for, and why so expensive?? Wow, I can remember when I had to beg them to buy me a 30 meg PEAK hd for $800 to go with my MAC Plus... It seems the tables are turned in a sense, Now the IBMers are getting ripped for their simms while MAC hd prices continue to drop (not to mention simm prices) Later, Mark Sartor, 221 Ag Hall MSU Campus, E. Lansing MI, 48823 - --> 18215mes@msu.bitnet
bayes@hpislx.HP.COM (Scott Bayes) (08/26/89)
It sure seems likely to me that the extra chips are there for Error Correcting Codes (ECC). Parity (9-bit SIMMs) allows the machine to detect a single bit error in a byte. Parity checking can (will) miss 2 bit errors in the same byte. ECC can (I forget the details) detect up to 4(?) bit errors in a byte, and can _correct_ up to 2 or 3 bit errors in the byte. The extra chips provide info required for correcting the errors. Scott Bayes