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How DRAM changed the world

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Re: How DRAM changed the world

#111

Post by rasz »

phil21 wrote: post #26
CalRobert wrote: post #25

Earlier quoted context omitted.

How so?

8GB -> 32GB doesn't really give you a whole lot more than opening more browser tabs or whatnot. Cache some more filesystem into memory I suppose. 8MB -> 32MB enabled entirely new categories of (consumer-level) software. It would be a game changer for performance as you were no longer swapping to (exceedingly slow) disk. They simply are not comparable, imo. 8MB to 32MB was night and day difference and you would drool…

Depends on your definition of "there". Going from 8MB to 32MB did very little for you pre Windows95. Every piece of x86 software up to that point was maxing below 8MB because ram was insanely expensive and you needed to populate 4 modules at a time. Motherboards came standard with 4 or 8 ram slots limiting your ram choices to 1,2,4,5,8,16,17,20,32 MB with last 4 costing more than motherboard and CPU combined.

In 1992 standard desktop was still 386 + 4MB, with highend 486 + 8MB. 1MB SIMM was $30-50. 4MB $150 January 1992, dropping to $100 in December 1992, and back to $130 in December 1994.

Afaik 72 pin simms were first introduced in 1989 IBM PS/2 (55SX? proprietary variant) and later around 1993 in clones. You could run 1,2,3 or 4 simms of any size independently. In December 1994 2MB 72pin Simm was $80, 4MB $150, 8MB $300, 16MB $560. 32MB $1200, 64MB $2800.

486DX2-66 itself was ~$300, + $100 VLB motherboard meanwhile $1100 got you Pentium 90MHz with PCI motherboard. In December 1994 for the price of 486 with 32MB ram ($1600) you could have bought P90 with 16MB ($1660).

Re: How DRAM changed the world

#112

Post by bloedsinnig »

OptionOfT wrote: post #77
bloedsinnig wrote: post #55

Earlier quoted context omitted.

1080p looks different to 4k. Just because its 'plenty' doesn't mean 4k doesn't matter. And we are at 2024, i own a 4k lg oled display now for years. Why not leverage it? Just because 1080p is 'plenty'?

The problem with 4k, which 99% of people only experience as a stream, is that it's over-compressed. A 1080p BluRay is 36 Mbit. Netflix 4k is 15 Mbit. So unless I see people mentioning the media, I am always weary of the comparison.

I have watched plenty of movies from a bluray.

Nonetheless, i do think that compression from a high res source looks different / sharper.

Re: How DRAM changed the world

#113

Post by guenthert »

phil21 wrote: post #26
CalRobert wrote: post #25

Earlier quoted context omitted.

How so?

8GB -> 32GB doesn't really give you a whole lot more than opening more browser tabs or whatnot. Cache some more filesystem into memory I suppose. 8MB -> 32MB enabled entirely new categories of (consumer-level) software. It would be a game changer for performance as you were no longer swapping to (exceedingly slow) disk. They simply are not comparable, imo. 8MB to 32MB was night and day difference and you would drool…

Dunno. Early nineties I had to shut down the X11 server to compile Linux on my 386 with 8MiB RAM, else the machine would thrash. Mid-nineties on a 486 with 16MiB Linux compiled happily in the background while the host remained usable, including GUI (might also have been due to then still rapid improvements in Linux itself).

Now my 8GiB Apple mini feels overworked and swaps a lot (quite noticeable so due to the spinning rust drive), while my laptop with 32GiB never breaks a sweat.

The real jump was when finally leaving behind my 8bit home computer (upgraded to 64+256KiB RAM of which most were usable only as RAM disk) when I got the 386 with 4MiB (soon maxed out at 8MiB). Now, that was a game changer.

Re: How DRAM changed the world

#114

Post by guenthert »

myself248 wrote: post #83
kstrauser wrote: post #79

Earlier quoted context omitted.

Why would we use DRAM, then? It seems better not to have to refresh it all the time. (I think I more or less know, but I’d rather talk about it than look it up this morning.)

Because SRAM is essentially a flipflop gate. It takes at least four transistors to store a single bit in SRAM, some designs use six. And current must continuously flow to keep the transistors in their state, so it's rather power hungry. One bit of DRAM is just one transistor and one capacitor. Massive density improvements; all the complexity is in the row/column circuitry at the edges of the array. And it only burns…

A nitpick: if the chip is manufactured in CMOS technology (as it's typically done), then no, current does not have to flow to keep the transistors' state (it's sufficient that a potential difference is maintained), only to change it. There's a tiny leakage current however, which over a few billion transistors adds up.

Re: How DRAM changed the world

#115

Post by TheAmazingRace »

mumblemumble wrote: post #68
tomnipotent wrote: post #36

Earlier quoted context omitted.

Most RAM found in consumer PC's during the 90s was still DRAM, including SDRAM, EDO, and Rambus. I believe OP is just being nostalgic over the period of time when RAM upgrades were very a exciting thing, as hardware was changing very quickly in that era and each year felt considerably more capable than the prior.

I'm not sure it's easy to understand what a big change there has been in the perceived pace of computer technology development if you weren't there. I'm typing this on a laptop that I purchased 11 years ago, in 2013. It's still my one and only home computer, and it hasn't given me any trouble. In 1994, though, an 11 year old computer would already be considered vintage . In 1983 the hot new computer was the Commodore…

Hilariously enough, you could still purchase a brand new Commodore 64 in 1994... albeit right before Commodore went bankrupt in May of that year. I vaguely remember some local electronics store in Pittsburgh having Commodore 64s for sale on the store shelves for really low prices back in the day. Admittedly, this was an unusual sight to behold in the US, because we had well since moved on to IBM PC Compatibles by then. In Europe, C64s were a tad bit easier to source.

It was definitely more of a curiosity and a toy rather than a serious computer in 1994.

Re: How DRAM changed the world

#116

Post by [deleted] »

Salgat wrote: post #18
MichaelZuo wrote: post #2

Dennard scaling for SRAM has certainly halted, as demonstrated by TSMC’s 3nm process vs 5 nm. What’s the likely ETA for DRAM?

5nm can hold roughly a gigabyte of SRAM on a cpu-sized die, that's around $130/GB I believe. At some point 5nm will be cheap enough that we can start considering replacing DRAM with SRAM directly on the chip (aka L4 cache). I wonder how big of a latency and bandwidth bonus that'd be. You could even go for a larger node size without losing much capacity for half the price.

[deleted]

Re: How DRAM changed the world

#117

Post by sundvor »

smolder wrote: post #35
sundvor wrote: post #31

Earlier quoted context omitted.

My DDR4 was C16, but my DDR5 at C30 makes up for that with sheer speed. Currently sporting this - G.Skill Trident Z5 Neo RGB Black 64GB (2x32GB) PC5-48000 (6000MHz) with a 7800x3d. Previous kit was G.Skill Trident Z Neo RGB 32GB (2x16GB), PC4-28800 (3600MHz) DDR4, 16-16-16-36 [X2, eventually, for 64 total] with, you guessed it, the 5800x3d, from the 3900xt - my son loves it.

To reiterate the GPs point, in case anyone didn't get it: DDR4-3200 CL16 is equivalent to DDR5-6000 CL30 or DDR5-6400 CL32 in terms of latency. Divide the frequency by the CAS latency and you get the same number for all of those. It was the same situation going from DDR3 to 4. There's some wiggle room if you run above-spec voltages (and depending on the quality of the chips, etc.) but things have stayed roughly where…

True! I realise that I left it unsaid in the numbers. Granted, herz for herz my DDR4 3600-CL16 had even better latencies than my DDR5 (4.44ns vs 5.00nz) - but for overall performance the speed then tends to make up for it (assuming a varied workload).

I've actively shopped for low latency RAM - within reasons, but have paid good premiums especially in DDR4 days. For DDR5, there can be surprisingly little price wise to differentiate e.g. CL30 or CL32, so whilst it may not offer the greatest of differences, if you're already paying e.g. $350 (AUD) for a kit at CL32 the improved latency might just be $20 more at the same speed.

(I see that things have moved on a bit from last September when I did my last upgrade; now we have CL32 at higher speeds, so maybe that's the go to now.)

Re: How DRAM changed the world

#118

Post by guerrilla »

ghaff wrote: post #65
MichaelZuo wrote: post #61

Earlier quoted context omitted.

Where’s the market demand for that?

Yeah, you’re basically betting that people will put a lot of effort in trying to out/optimize the hardware and perhaps to some degree the OS. Not a good bet. When SMP first came out we had one large customer that wanted to manually handle scheduling themselves. That didn’t last long.

Effort? It's not like it's hard to map an SRAM chip to whatever address you want and expose it raw or as a block device. That's a 100 LOC kernel module.

Re: How DRAM changed the world

#119

Post by anticensor »

asdefghyk wrote: post #95
dehrmann wrote: post #88

Earlier quoted context omitted.

It isn't the point of the article, but this is true of every storage medium. It's just a question of milliseconds or years.

Static RAM ( based on how it is used) never needs to be refreshed at current typical computer power on times (hours or days ) . Current DRAM must be refreshed at very much faster rates to be able to be useful.

As in multiple times a second.

Re: How DRAM changed the world

#120

Post by anticensor »

rasz wrote: post #109
hajile wrote: post #96

Earlier quoted context omitted.

The capacitors take time to charge and discharge. You can't do that more than around 400MHz with current materials. You are correct that it means you can't access the same bit of memory more than 400M/sec. This is the same whether you are accessing 1bit or 1M bits because the individual capacitors that make up those bits can't be charged/discharged any faster. When we moved from SDR to DDR1, latencies dropped from 20…

Yep, we pretty much hit a wall during DDR2 rein https://en.wikipedia.org/wiki/CAS_latency#Memory_timing_exam...

No, 7.5 to 9.75ns during the DDR4 rein (DDR4-4266), according to that page.
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