[comp.sys.ibm.pc.hardware] Do you need 1M on video card for non-interlaced 1024x768

nbeck@weber.ucsd.edu (Nathaniel Beck) (04/07/91)

I am getting a 486 system. I want to be able to use 1024x768 (or
whatever the correct numbers close to that are) on a non-interlaced
monitor (a Seiko 1450, I think). One vendor has told me I need 1M on
the video card to support non-interlaced SVGA, another has said that
a much cheaper (ATI Wonder) card with only 512K will do. Which
vendor is correct, or am I totally confused, or both?

Thanks in advance

Neal Beck

-- 
Neal Beck 
Dept of Politcal Science, UCSD
beck@ucsd.edu
Dislaimer: The Regents pay me (a bit!) to distribute my opinions.

jayh@ms.uky.edu (Jay Hofacker) (04/07/91)

A S-VGA card is adequate for 1024x768 with 16 colors.  In order to do 1024x768
with 256 colors, you need 1 Meg of RAM.

I personally have a clone VGA card (the name in the docs, on the card, and in
the BIOS are all three different...) based on the Tseng4000 chipset.  It was
about $140 (cheapest I could find mail order) and came with 1 meg of Ram. 


-- 
Jay Hofacker, sysop of the Audio/Visual Exchange, (606)254-1751 3/12/24 MNP 5
Mail: jayh@ms.uky.edu / uk02779@ukpr.uky.edu -- Yes, my signature is only 2 lin

alun@sunatb.UUCP (Alun Saunders) (04/08/91)

nbeck@weber.ucsd.edu (Nathaniel Beck) writes:

>I am getting a 486 system. I want to be able to use 1024x768 (or
>whatever the correct numbers close to that are) on a non-interlaced
>monitor (a Seiko 1450, I think). One vendor has told me I need 1M on
>the video card to support non-interlaced SVGA, another has said that
>a much cheaper (ATI Wonder) card with only 512K will do. Which
>vendor is correct, or am I totally confused, or both?

>Thanks in advance

>Neal Beck

If you only want to use 16 colours then 512k is fine, only if you want
to do 1024x768x256 do you need the full 1 Meg.

You can quite easily confirm this by working out 1024*768=768k. For 16
colours you only need 4 bits per pixel, ergo you only need 384kbytes
video memory. For 256 colours you need 1 whole byte per pixel, i.e.
768kbytes.  The next round figures for these amounts are 512k and 1M
respectively.

BTW, the interlaced vs. non-interlaced issue has no effect whatsoever on
the amount of memory you need. Its only a question of timing on the
card.

Hope this is useful.

Alun Saunders