Checksum: 16354 Path: utzoo!utgpu!adam From: adam@gpu.utcs.toronto.edu (Adam R. Iles) Date: Fri, 15-Jul-88 13:27:14 EDT Message-ID: <1988Jul15.132714.24898@gpu.utcs.toronto.edu> Organization: University of Toronto Computing Services Newsgroups: comp.sys.ibm.pc Subject: Re: PC/XT 286-based accelerator opinions wanted References: <14382@shemp.CS.UCLA.EDU> Reply-To: adam@gpu.utcs.UUCP (Adam R. Iles) In article <14382@shemp.CS.UCLA.EDU> wales@CS.UCLA.EDU (Rich Wales) writes: >My system has an 8-MHz NEC V-20 CPU. The clock speed is software- >switchable to either 4.77 or 8 MHz. The RAM chips are 150-nsec. >The accelerator I am currently thinking of is the "Orchid Tiny Turbo >286" -- a half-sized card unit with room to add an 80287 coprocessor. A week ago I purchased just such a card for a similar setup (except I'm using a 8088-2 and it's not software switchable.) The documentation, however, SUGGESTS that you DON'T use it with a turbo system or a 8088-2, V-20 or several other replacement chips. This card comes with an 80286 and an 8K cache on an 16 bit bus (to the 80286.) >the back of the computer which lets you select either the 286 or your >original CPU. The Orchid also claims to be usable at either 5 (I assume >they really mean 4.77) or 8 MHz. This is reffering to the 80287 not the 8088 or equivilent :-( which leaves you with only the 4.77 Mhz bus. >Does anyone out there who is using (or has tried) the Orchid Tiny Turbo >286 know whether it can in fact be used in an 8-MHz turbo XT? Would I >be able to drive it at the 8 MHz clock speed? Even at the standard 4.77 >MHz speed, how much faster is it going to be than my current NEC V-20 >system at 8 MHz? Would I have to replace my 150-nsec RAM chips with >120's (or faster?) in order for an accelerator to be worth the expense? I haven't had much time to test the board thuroughly, but it seems to run fine at 4.77 MHz, but it won't run at 8 Mhz at all. Since I don't have a V-20 in my machine I can't compare it to the V-20, but it seems to run some programs at upto 4X as fast as the 8088-2 (at 4.77 Mhz.) One thing to remember is that the Tiny Turbo is still going through the 4.77 Mhz 8-bit bus so disk accesses and memory fetches outside the cache will be as slow as a regualar PC. If you run programs that execute a lot of tight loops and aren't I/O intensive it should do a good job at improving their performance, though. >-- Rich Wales // UCLA Computer Science Department // +1 (213) 825-5683 > 3531 Boelter Hall // Los Angeles, California 90024-1596 // USA > wales@CS.UCLA.EDU ...!(uunet,ucbvax,rutgers)!cs.ucla.edu!wales > "We would all become unpeople, undoing unthings untogether." Adam Iles -- adam@utgpu -- adam@vm1.utcs.utoronto.ca All comments above do not necessarily reflect the beliefs or opinions of any person alive or otherwise. -- Any opinions stated above may, or may not, refect those of any sane person living, dead, or just sleeping. Adam R. Iles: adam@utgpu