sunyat@itsgw.rpi.edu (Eric Hsiao) (12/24/90)
Hi, I got a 16 bit VGA card that currently has only 256K on it. I want to
upgrade it to 512K so I can display 640x480x256, 800x600x256, 1024x768x16, etc.
The manual says I need 256Kx4 Fast Page Mode Dram (sometimes called 1-Mbit
DRAM). Anyone know where I can get these chips at a reasonable price ($15-$20)?
Does it matter whether I get 80ns or 100ns? Will it increase the speed of
the display card?
Eric
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In article <62M^M8#@rpi.edu> sunyat@itsgw.rpi.edu (Eric Hsiao) writes:
$Hi, I got a 16 bit VGA card that currently has only 256K on it. I want to
$upgrade it to 512K so I can display 640x480x256, 800x600x256, 1024x768x16, etc.
$The manual says I need 256Kx4 Fast Page Mode Dram (sometimes called 1-Mbit
$DRAM). Anyone know where I can get these chips at a reasonable price ($15-$20)?
Are you sure your manual is correct? If it's a 16-bit card using 256Kx4
chips, the minimum amount of memory on it would be 512K (because you'd need
four chips to make it 16 bits wide, and that would be 256Kx16 bits = 512K).
I haven't seen a VGA card that uses 256Kx4 chips (though that certainly
doesn't mean there aren't any). Have a look at your board and count the
number of RAM chips on it.
The other alternative is that it doesn't use 256Kx4 chips for 256K, and
then you'd end up eating the chips currently on it ...
$Does it matter whether I get 80ns or 100ns? Will it increase the speed of
$the display card?
It probably doesn't matter, and getting fast RAM won't speed up your board
because it's built to assume a certain clock speed; anything faster is
wasted. Look at the numbers on your RAM chips. If they end in -10, they're
100 ns. In any case, if the manual doesn't say what the slowest acceptable
chips are, then buy the same speed as the chips on your board.
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_____________________/ find / -print|xargs cat|compress | SNTFphil@brahms.amd.com (Phil Ngai) (12/27/90)
In article <1990Dec25.172332.14826@xrtll.uucp> silver@xrtll.UUCP (Hi Ho Silver) writes: | Are you sure your manual is correct? If it's a 16-bit card using 256Kx4 |chips, the minimum amount of memory on it would be 512K (because you'd need |four chips to make it 16 bits wide, and that would be 256Kx16 bits = 512K). Wrong. I know (intimately) at least one (Super) VGA chipset that offers a 16-bit interface to the ISA bus using only two 256Kx4 RAM chips. How do they do it? Think about it... |I haven't seen a VGA card that uses 256Kx4 chips (though that certainly |doesn't mean there aren't any). Have a look at your board and count the There are several. Why do people like to post when they don't really know? -- Whatever happened to Global Warming? Could we have some Local Warming?
plim@hpsgwp.sgp.hp.com (Peter Lim) (12/28/90)
/ phil@brahms.amd.com (Phil Ngai) / 3:35 am Dec 27, 1990 / writes: > > Wrong. I know (intimately) at least one (Super) VGA chipset that offers a > 16-bit interface to the ISA bus using only two 256Kx4 RAM chips. How do > they do it? Think about it... > Two 256Kx4 RAM chips only give you 256K x 4 / 8 = 128K byte RAM. Is that enough to qualify it as superVGA ? Considering SuperVGA means at least 640 x 480 x 256 colors => 640 x 480 bytes = 300 Kbytes ! >> 128 Kbytes. That aside, assuming you have two 256Kx4 chips. That means that you can only write 8 bit in one time into those two chips. Other than inserting wait state and do the 16 bit write from the bus as two 8 bit writes on the VGA board, I don't see how you can do full 16 bit write. Not that most VGA card don't insert wait state :-). If it is done any other way, can you let us know ? Regards, . .. ... .- -> -->## Life is fast enough as it is ........ Peter Lim. ## .... DON'T PUSH IT !! >>>-------, ########################################### : E-mail: plim@hpsgwg.HP.COM Snail-mail: Hewlett Packard Singapore, : Tel: (065)-279-2289 (ICDS, ICS) | Telnet: 520-2289 1150 Depot Road, __\@/__ Singapore 0410. SPLAT ! #include <standard_disclaimer.hpp>
silver@xrtll.uucp (Hi Ho Silver) (12/30/90)
In article <3370003@hpsgwp.sgp.hp.com> plim@hpsgwp.sgp.hp.com (Peter Lim) writes:
$Two 256Kx4 RAM chips only give you 256K x 4 / 8 = 128K byte RAM.
Wrong. One 256Kx4 RAM chip gives you 256Kbitsx4/8=128Kbyte RAM. Two
256Kx4 RAM chips give you 256Kx4x2=256Kx8=256Kbytes.
BUT
It's only 8 bits wide, and putting 8-bit RAM on a a 16-bit VGA card is a
rather daffy idea (either that, or a sleazy marketing trick). Yeah, it's
possible to add some circuitry to make it appear to be 16 bits wide, but
the fact is you're never going to get more than 8 bits at a time out of
it. I can design a 16-bit-wide interface to a 1Mx1 chip, and it will seem
to the CPU to be 16 bits wide. No problem, if you don't mind a greatly
diminished MTBF and losing about 94% of the performance.
So, Phil, would you care to tell us all about how this particular
chipset gets 16-bit access to 8-bit memory?
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_____________________/ find / -print|xargs cat|compress | SNTFplim@hpsgwp.sgp.hp.com (Peter Lim) (12/31/90)
> $Two 256Kx4 RAM chips only give you 256K x 4 / 8 = 128K byte RAM. > > Wrong. One 256Kx4 RAM chip gives you 256Kbitsx4/8=128Kbyte RAM. Two > 256Kx4 RAM chips give you 256Kx4x2=256Kx8=256Kbytes. > Oops ! Me and my fat finger. I forgot the Two in the Two chip. So, you are right, it is 256K byte. I apologize. Regards, . .. ... .- -> -->## Life is fast enough as it is ........ Peter Lim. ## .... DON'T PUSH IT !! >>>-------, ########################################### : E-mail: plim@hpsgwg.HP.COM Snail-mail: Hewlett Packard Singapore, : Tel: (065)-279-2289 (ICDS, ICS) | Telnet: 520-2289 1150 Depot Road, __\@/__ Singapore 0410. SPLAT ! #include <standard_disclaimer.hpp>
mir@opera.chorus.fr (Adam Mirowski) (12/31/90)
As for the bus width problem: 16-bit-bus cards with 256x4 chips could be internally 8 bit when equiped with only 2 chips (256 Kb) and become true 16 bits when equiped with more RAM. On my Trident 8900 (1Mb) card, there are 8 slots for 256x4 chips. Why would one brain-damage a higher end card with slow memory access? Anyway: 16-bit cards are allowed three 125 ns bus cycles on every access. They may request additional ones if they want but can't announce that they don't need as much time. That makes 375 ns which is enough for the card to perform many internal transfers, including multiple writes/reads to/from its internal 8 bit memory. Correct me if I'm wrong. -- Adam Mirowski, mir@chorus.fr (FRANCE), tel. +33 (1) 30-64-82-00 or 74 Chorus systemes, 6, av.Gustave Eiffel, 78182 Saint-Quentin-en-Yvelines CEDEX
sunyat@itsgw.rpi.edu (Eric Hsiao) (01/08/91)
Hi - I'm the original poster of the question on the VGA upgrade to 512K
It's a Trident 8900 board..the brand name is called Paellite (something
like that, it was $90)..The manual says Super 8900 on it. And the manual
does say 256x4 Fast Page Mode DRAM..so basically, did I get ripped off with
this board? Where can I get this 256x4 chips? I've got two already on the
card which makes up 256K and need 2 more to get 512K.
Eric
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| Internet: Eric_Hsiao@MTS.RPI.EDU > Read GIF News - a freely copied news < |
| sunyat@PAWL.RPI.EDU > magazine in .GIF file format. Color < |
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| FTP to wuarchive "gn90-11.zip" > games, industry news, IBM, Amiga, etc.< | ong@d.cs.okstate.edu (ONG ENG TENG) (01/08/91)
From article <CNX^HV-@rpi.edu>, by sunyat@itsgw.rpi.edu (Eric Hsiao): > Hi - I'm the original poster of the question on the VGA upgrade to 512K > It's a Trident 8900 board..the brand name is called Paellite (something > like that, it was $90)..The manual says Super 8900 on it. And the manual > does say 256x4 Fast Page Mode DRAM..so basically, did I get ripped off with > this board? Where can I get this 256x4 chips? I've got two already on the > card which makes up 256K and need 2 more to get 512K. I think the DRAM that you need are 44256's, which you can buy from almost any computer component shop (where you buy your second floppy drive, serial card, etc). You also need to look at your current set of chips on the VGA card to see what speed is required. But again, I could be wrong about the 44256's. Anyone else care to comfirm or contradict?