lane@cs.dal.ca (John Wright/Dr. Pat Lane) (06/20/89)
We have some 286 and 386 machines that came with Renaissance RGVA1 VGA
cards. I notice that these are only 8-bit (ie. go into the short slots).
I thought VGA cards were typically 16-bit (have both interface connectors).
Also the doc. says they have 256K RAM (there are 8 MT4067-12 chips on the
card). Don't the better VGA card come with 512K? (As you might tell, I
know diddly about VGA.)
The question? Are we and how badly are we getting hosed here?
While I'm on it, we got Tatung CM-1496 analog monitors. Haven't seen any
reviews (I suspect they may be marketed under other names). Anyone have
any opinions on these?
--
John Wright ////////////////// Phone: 902-424-3805 or 902-424-6527
Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8
Cdn/Eannet:lane@cs.dal.cdn Uucp:lane@dalcs.uucp or {uunet watmath}!dalcs!lane
Arpa:lane%dalcs.uucp@uunet.uu.net Internet:lane@cs.dal.cakji@vpnet.UUCP (Ken Isacson) (07/04/89)
I regards to VGA cards and memory this is the scoop. According to a recent article in PC Magazine 256K memory is just fine. You only need the extra memory when you move up to hi video modes with the 256 colors. However, according the specs for VGA the hi modes need only the 16 colors. The advantage of the 16 bit cards is that they are about twice as fast because the computer can get the video information to the card 16 bits at a time as oppose to 8 bits at a time. Hope this helps.
chasm@attctc.DALLAS.TX.US (Charles Marslett) (07/05/89)
In article <[267.1]comp.sys.ibm.pc;1@vpnet.UUCP>, kji@vpnet.UUCP (Ken Isacson) writes: > The advantage of the 16 bit cards is that they are about twice as fast because > the computer can get the video information to the card 16 bits at a time > as oppose to 8 bits at a time. Any VGA or EGA card running in the industry standard 16-color modes (as opposed to the totally non-standard modes that ET3000 and C&T 441 based cards can use -- that are really PC Jr. modes in disguise), WILL BE RUNNING AS AN 8-BIT CARD. 16 bit cards are faster in the 256 color modes (almost all of which will require 512K of RAM) and text modes (which are plenty fast for most of us anyway). There is a minor point I am ignoring here: even in the 16-color modes, the EGA/VGA interface can do 16-bit I/O instructions, so standard BIOS access to the video memory (highly I/O intensive!) will be significantly faster on a 16-bit card that supports 16-bit I/O instructions. On the other hand, efficient drivers for most screen intensive software will run just about the same speed on an 8-bit card as on a 16-bit card. > Hope this helps. Ditto... =========================================================================== Charles Marslett STB Systems, Inc. <== Apply all standard disclaimers Wordmark Systems <== No disclaimers required -- that's just me chasm@killer.dallas.tx.us <== soon to be attctc.dallas.tx.us I think
las) (07/05/89)
In article <8529@attctc.DALLAS.TX.US> chasm@attctc.DALLAS.TX.US (Charles Marslett) writes: >In article <[267.1]comp.sys.ibm.pc;1@vpnet.UUCP>, kji@vpnet.UUCP (Ken Isacson) writes: >>[16-bit vga cards are about twice as fast as 8 bit cards] >[Not necessarily. Only for 256-color modes (ignoring quality of device >driver software).] Since Charles is from STB systems, this lends credibility to his remarks. I would still like to know, however, has anyone made an effort to measure and compare the differences? Will whoever does so publish this informat- ion if it is not already published? If published, where? I don't want to see another scorecard comparing only 8-bit cards against each other or 16-bit cards against each other. I want to see comparisons of 8- and 16-bit cards using the same tests and the test systems. Would people *who actually design these things* please tell us more? === ======== ====== ===== ====== I want to read/hear real technical discussions about this hardware. It's a lot more than "16 bits is twice as many as 8 bits therefore it is twice as fast." This remark has some (not complete!) validity in a comparison of 8- versus 16-bit DMA and, hence, of hard disk controller cards. There are, however, additional complicating factors with graphics cards such as contention for access to the video RAM, design of the video RAM architec- ture, and who knows what all, which keep the discussion from being as simple as that. regards, Larry -- Signed: Larry A. Shurr (cbema!las@att.ATT.COM or att!cbema!las) Clever signature, Wonderful wit, Outdo the others, Be a big hit! - Burma Shave (With apologies to the real thing. The above represents my views only.) (Please note my mailing address. Mail sent directly to cbnews doesn't make it.)
scottw@ico.ISC.COM (Scott Wiesner) (07/06/89)
From article <7964@cbnews.ATT.COM>, by cbema!las@cbnews.ATT.COM (cbema!las): > In article <8529@attctc.DALLAS.TX.US> chasm@attctc.DALLAS.TX.US (Charles Marslett) writes: >>In article <[267.1]comp.sys.ibm.pc;1@vpnet.UUCP>, kji@vpnet.UUCP (Ken Isacson) writes: >>>[16-bit vga cards are about twice as fast as 8 bit cards] > >>[Not necessarily. Only for 256-color modes (ignoring quality of device >>driver software).] > > Since Charles is from STB systems, this lends credibility to his remarks. > I would still like to know, however, has anyone made an effort to measure > and compare the differences? Will whoever does so publish this informat- > ion if it is not already published? If published, where? I don't have measurements that I can give out, but I can say that for the X server I've worked on, the difference between 8 bit and 16 bit cards is very minimal in the standard 16 color VGA modes. As Charles mentioned, you get a bit of an advantage with 16 bit cards since the i/o is really 16 bit, but other than that, the EGA/VGA is still basically an 8 bit device. The problem is that everything you do one one of these cards goes through a set of 8 bit wide latches. Driving 16 bits of data at once to the card just makes the card do 2 8 bit operations. In fact, due to the programming model for the VGA, you often are forced to do 8 bit operations anyway. Now that I've said all that, I'll also say that the way things have worked out, there does tend to be a bit of a difference between 8 and 16 bit cards. The 16 bit cards tend to be newer, slightly better designs, resulting in better operation. The Headland (formerly Video 7) cards are definately faster that other cards. The Tseng Labs based cards (STB, Orchid, Genoa, etc) aren't as fast, but seem to be a very good value. If you're really concerned about performance, wait 6 months and go for one of the 8514/A clones that will be coming out. For around $1000, you'll get 1024x768 with 256 colors, and some hardware assist in the area that needs it the most (bitblit). Scott