martyl@rocksvax.UUCP (03/14/87)
I just received a leased PC AT. A few questions about PC AT's in general: 1) How can I tell the difference between 6 meg and 8meg PC AT's without opening them up and looking inside or running some type of benchmark on them? I use a Model 339 at work (8 Meg one), but where in the world do they distinguish the model? Outward appearances of 6 meg and 8meg models don't seem to provide a clue. They just seem to say "PC AT". 2) The leased unit I received has 256k of RAM on the motherboard, and an additional 384k on an 8 bit expansion board to bring it up to 640K (I didn't ask for this configuration, this is just the way it came). Does it make sense to run 8 bit memory on a PC AT? It seems to me doing PC bus operations will make the CPU pay a dear penalty (i.e. I just got the unit yesterday and it's powerup ram tests seem awfully slow. I use both a 6 meg and 8 meg unit everyday, each with 512 k on the motherboard. Doing tests on another 128k of Ram appears at least twice as slow [this is just an impression]). Would it be worth repopulating the motherboard with another 256k of dram? 3) The monitor I got is an IBM monochrome monitor. It seems to have unusually long persistence (on the order of 15 seconds). When the screen scrolls, it is unreadable for 15 seconds or so until things settle down. After- wards the image appears normal. Is there a simple adjustment on the monitor to control persistence? I really don't want have to give it back for service which may take several weeks (for want of a monitor, the PC was lost). If it just involves tweaking a pot, I'd rather do it myself. marty leisner xerox corporation leisner.henr@xerox.com (preferred address) martyl@rocksvax.uucp (alternate)
pgc#@andrew.cmu.edu (Paul G. Crumley) (03/17/87)
ReSent-From: postman#@andrew.cmu.edu ReSent-To: nntp-xmit#@andrew.cmu.edu Return-path: <pgc#@andrew.cmu.edu> X-Trace: MS Version 3.21 on ibm032 host talleycavey, by pgc (42). To: outnews#ext.nn.comp.sys.ibm.pc@andrew.cmu.edu, martyl@rocksvax.UUCP (Marty Leisner) In-Reply-To: <868@rocksvax.UUCP> in response to a few questions: 1) I think the only way to tell is to look at the model number on the back of the unit or to look at the BIOS. This is not foolproof as many people install various "speed-up" devices to make the 6 MHz machine act like 8 MHz machines. 2) The 8 bit RAM will perform about 4 times slower for word access and about 2 times slower for byte access. 3) Persistence is dependent on the type of phospor used in the monitor. Sometimes playing with the constrast and brightness controls will help a bit but in general, the type of phospor is the critical factor. Best regards, Paul