4 ms·

Okay but "640" is a completely fictitious number for installed RAM in any given PC. PC memory was nearly always sold in powers of two. So you could have SIMMs

Okay but "640" is a completely fictitious number for installed RAM in any given PC. PC memory was nearly always sold in powers of two. So you could have SIMMs in capacity of 1MiB, 2MiB, 4, 8, 16MiB. You could usually mix-and-match these memory modules, and some PCs had 2 slots, some had 4, some had a different number of slots. So if you think about 4 slots that can hold some sort of maximum, we're thinking 64MiB is a very common maximum for a consumer PC, and that may be 2x32 or 4x16MiB. Lots of people ran up against that limit for sure. 640MiB is an absurd number if you think mathematically. How do you divide that up? If 4 SIMMs are installed, then their capacity is 160MiB each? No such hardware ever existed. IIRC, individual SIMMs were commonly maxed at 64MiB, and it was not physically possible to make a "monster memory module" larger than that. Furthermore, while 64MiB requires 26 bits to address, 640MiB requires 30 address bits on the bus. If a hypothetical PC had 640MiB in use by the OS, then only 2 pins would be unused on the address bus! That is clearly at odds with their narrative that they were able to "borrow" several more! This is clearly a typo and I would infer that the author meant to write "64 megabytes" and tacked on an extra zero, out of habit or hyperbole.

chadaustin 1y ago
You are straight up wrong. The first computer I ever built was a Pentium 2, RivaTNT, and it had 640 MB RAM. I can’t find the purchase receipts or specific board brand but it had four SDRAM slots, and I had it populated with 2x64 and 2x256. Edit: Found it in some old files of mine: I was wrong! Not four DIMM slots... three! One must have been 128 and the other two 256. Pentium II 400, 512k cache Abit BF6 motherboard 640 MB PC100 SDRAM 21" Sony CPD-G500 (19.8" viewable, .24 dot pitch) 17" ViewSonic monitor (16" viewable, .27 dot pitch) RivaTNT PCI video card with 16 MB VRAM Creative SB Live! Creative 5x DVD, 32x CD drive Sony CD-RW (2, 4, 24) 80 GB Western Digital ATA/100 40 GB Western Digital ATA/100 17.2 GB Maxtor UltraDMA/33 HDD 10.0 GB Maxtor UltraDMA/33 HDD Cambridge SoundWorks FourPointSurround FPS2000 Digital 3Com OfficeConnect 10/100 EtherNet card 3 Microsoft SideWinder Gamepads Labtec AM-252 Microphone Promise IDE Controller card Hauppage WinTV-Theatre Tuner Card
- AStonesThrow 1y ago
  Alright then! Humbly, I stand corrected about my poor speculation without research. It looks like 640MiB has been a perfectly achievable configuration, especially with 2x256+2x64 or such. That is, I must say, a huge amount of RAM. Like, way more than any video game ever specified in HW requirements. What use cases applied that you could use up 640MiB in that era, I wouldn't know! I remain a bit mystified about why it would be a hard maximum, though. Did such motherboards prevent the user from installing 4x256MiB for a cool 1GiB of DRAM? Was the OS having trouble addressing or utilizing it all? 640MiB is not a mathematical sort of maximum I was familiar with from the late 1990s. 4GiB is obviously your upper limit, with a 32-bit address bus... and again, if 640MiB were installed, that's only 2 free bits on that bus. So I'm still a little curious about this number being dropped in the article. More info would be enlightening! And thank you for speaking up to correct me! No wonder it was down-voted!
  - chadaustin 1y ago
    I did a bunch of media and software development back then so RAM helped a lot. Why 640? Not sure. My particular board could have gone up to 768. I did some googling and found some boards that maxed out at 1 GB. That was a weird time in computing. Things were getting fast and big quickly (not that many years later, I built a dual-socket Xeon at 2.8 GHz, and before that my brother had a dual socket P3 at 700 MHz.) but all the expansion boards were so special-purpose. I remember going out of my way to pick a board with something like seven expansion slots. But I think your question about why the author said 640 is fair! Maybe they had a machine like mine around then. Or maybe it’s something NVIDIA was designing around?
  - tolien 1y ago
    > I remain a bit mystified about why it would be a hard maximum, though. Did such motherboards prevent the user from installing 4x256MiB for a cool 1GiB of DRAM? Probably not - it's not that rare to see the supported maximum memory be a function of the biggest DIMM you can buy, I guess as a reflection of the biggest configuration the manufacturer could test.
- trentnelson 1y ago
userbinator 1y ago
For a while, I had 36MB on a 486 mobo, with a combination of SIMMs and DIMMs. As others have mentioned, 640MB is a valid, if odd, configuration for RAM.
- rasz 1y ago
  Not a single 486 motherboard supported DIMMs.
  - AStonesThrow 1y ago
    The precise reason for this is straightforward: 486 processors had a 32-bit data bus, but DIMMs took advantage of the Pentium's new 64-bit wide bus, because otherwise users found themselves installing SIMMs in matched pairs in order to span that entire width. https://en.wikipedia.org/wiki/DIMM#History https://en.wikipedia.org/wiki/DIMM#History The GP may be thinking of double-sided modules, which could be SIMMs or could be DIMMs; it was just a matter of how the chips were arranged. https://en.wikipedia.org/wiki/Memory_rank#Details https://en.wikipedia.org/wiki/Memory_rank#Details
adrian_b 1y ago
As another poster has said, around 2000/2001 there were many PC motherboards for which the maximum RAM capacity was 640 MB of SDRAM (though depending on the motherboard the capacity limit could have other values, e.g. 512 MB or 768 MB were other frequent values). Only around 2003, motherboards where you could install up to 4 GB of DDR memory became widespread. I had a few such motherboards, with Pentium III "Coppermine" and with AMD Athlon "Thunderbird" (with 3 DIMM sockets, 2 accepting 256 MB modules and 1 accepting 128 MB modules). While I had initially equipped them with less memory, i.e. either 128 MB or 256 MB, because of the high cost at that time, eventually I had maxed up the installed memory to 640 MB on the Athlon motherboards. At that time, the memory controller was not included in the CPU, but it was contained in an external chip, the Northbridge. The MB chipsets could come from various vendors, including Intel and Via. Depending on the chipset, different maximum amounts of SDRAM could be supported. Sometimes there were also limits for the maximum amount of RAM caused by the L2 cache controller, due to the size of the tags required in cache lines. Even with the same chipset, the MB manufacturer could choose to route different numbers of address lines to the sockets, probably depending on whether the extra capacitive loading caused by a bigger memory module would have allowed it to function at the rated speed on that PCB. 64 MB would have been a typical maximum memory around 1998 (2 sockets for 32 MB SDRAM modules, on a MB with an AGP socket for the graphics card), so if the author would have had that year in mind, you would be right.
- LargoLasskhyfv 1y ago
  I had 1.5GB (3 x 512MB) Virtual Channel Memory (SDRAM) on a T-Bird. https://en.wikipedia.org/wiki/Synchronous_dynamic_random-access_memory#Virtual_channel_memory_(VCM)_SDRAM https://en.wikipedia.org/wiki/Synchronous_dynamic_random-acc... Undervolted and OC'd to 1800+ under Linux, 2100+ under NetBSD. Stable and rock-solid :-)
DonHopkins 1y ago
Haven't you ever heard the Bill Gates quote that he didn't actually say? https://news.ycombinator.com/item?id=18120477 https://news.ycombinator.com/item?id=18120477 https://groups.google.com/g/alt.folklore.computers/c/mpjS-h4jpD8/m/9DW_VQVLzpkJ https://groups.google.com/g/alt.folklore.computers/c/mpjS-h4... QUESTION: I read in a newspaper that in 1981 you said, ``640K of memory should be enough for anybody.'' What did you mean when you said this? ANSWER: I've said some stupid things and some wrong things, but not that. No one involved in computers would ever say that a certain amount of memory is enough for all time. The need for memory increases as computers get more potent and software gets more powerful. In fact, every couple of years the amount of memory address space needed to run whatever software is mainstream at the time just about doubles. This is well-known. When IBM introduced its PC in 1981, many people attacked Microsoft for its role. These critics said that 8-bit computers, which had 64K of address space, would last forever. They said we were wastefully throwing out great 8-bit programming by moving the world toward 16-bit computers. We at Microsoft disagreed. We knew that even 16-bit computers, which had 640K of available address space, would be adequate for only four or five years. (The IBM PC had 1 megabyte of logical address space. But 384K of this was assigned to special purposes, leaving 640K of memory available. That's where the now-infamous ``640K barrier'' came from.) A few years later, Microsoft was a big fan of Intel's 386 microprocessor chip, which gave computers a 32-bit address space. Modern operating systems can now take advantage of that seemingly vast potential memory. But even 32 bits of address space won't prove adequate as time goes on. Meanwhile, I keep bumping into that silly quotation attributed to me that says 640K of memory is enough. There's never a citation; the quotation just floats like a rumor, repeated again and again.

chadaustin 1y ago

You are straight up wrong. The first computer I ever built was a Pentium 2, RivaTNT, and it had 640 MB RAM. I can’t find the purchase receipts or specific board brand but it had four SDRAM slots, and I had it populated with 2x64 and 2x256. Edit: Found it in some old files of mine: I was wrong! Not four DIMM slots... three! One must have been 128 and the other two 256. Pentium II 400, 512k cache Abit BF6 motherboard 640 MB PC100 SDRAM 21" Sony CPD-G500 (19.8" viewable, .24 dot pitch) 17" ViewSonic monitor (16" viewable, .27 dot pitch) RivaTNT PCI video card with 16 MB VRAM Creative SB Live! Creative 5x DVD, 32x CD drive Sony CD-RW (2, 4, 24) 80 GB Western Digital ATA/100 40 GB Western Digital ATA/100 17.2 GB Maxtor UltraDMA/33 HDD 10.0 GB Maxtor UltraDMA/33 HDD Cambridge SoundWorks FourPointSurround FPS2000 Digital 3Com OfficeConnect 10/100 EtherNet card 3 Microsoft SideWinder Gamepads Labtec AM-252 Microphone Promise IDE Controller card Hauppage WinTV-Theatre Tuner Card

AStonesThrow 1y ago
Alright then! Humbly, I stand corrected about my poor speculation without research. It looks like 640MiB has been a perfectly achievable configuration, especially with 2x256+2x64 or such. That is, I must say, a huge amount of RAM. Like, way more than any video game ever specified in HW requirements. What use cases applied that you could use up 640MiB in that era, I wouldn't know! I remain a bit mystified about why it would be a hard maximum, though. Did such motherboards prevent the user from installing 4x256MiB for a cool 1GiB of DRAM? Was the OS having trouble addressing or utilizing it all? 640MiB is not a mathematical sort of maximum I was familiar with from the late 1990s. 4GiB is obviously your upper limit, with a 32-bit address bus... and again, if 640MiB were installed, that's only 2 free bits on that bus. So I'm still a little curious about this number being dropped in the article. More info would be enlightening! And thank you for speaking up to correct me! No wonder it was down-voted!
- chadaustin 1y ago
  I did a bunch of media and software development back then so RAM helped a lot. Why 640? Not sure. My particular board could have gone up to 768. I did some googling and found some boards that maxed out at 1 GB. That was a weird time in computing. Things were getting fast and big quickly (not that many years later, I built a dual-socket Xeon at 2.8 GHz, and before that my brother had a dual socket P3 at 700 MHz.) but all the expansion boards were so special-purpose. I remember going out of my way to pick a board with something like seven expansion slots. But I think your question about why the author said 640 is fair! Maybe they had a machine like mine around then. Or maybe it’s something NVIDIA was designing around?
- tolien 1y ago
  > I remain a bit mystified about why it would be a hard maximum, though. Did such motherboards prevent the user from installing 4x256MiB for a cool 1GiB of DRAM? Probably not - it's not that rare to see the supported maximum memory be a function of the biggest DIMM you can buy, I guess as a reflection of the biggest configuration the manufacturer could test.
trentnelson 1y ago

userbinator 1y ago

For a while, I had 36MB on a 486 mobo, with a combination of SIMMs and DIMMs. As others have mentioned, 640MB is a valid, if odd, configuration for RAM.

rasz 1y ago
Not a single 486 motherboard supported DIMMs.
- AStonesThrow 1y ago
  The precise reason for this is straightforward: 486 processors had a 32-bit data bus, but DIMMs took advantage of the Pentium's new 64-bit wide bus, because otherwise users found themselves installing SIMMs in matched pairs in order to span that entire width. https://en.wikipedia.org/wiki/DIMM#History https://en.wikipedia.org/wiki/DIMM#History The GP may be thinking of double-sided modules, which could be SIMMs or could be DIMMs; it was just a matter of how the chips were arranged. https://en.wikipedia.org/wiki/Memory_rank#Details https://en.wikipedia.org/wiki/Memory_rank#Details

adrian_b 1y ago

As another poster has said, around 2000/2001 there were many PC motherboards for which the maximum RAM capacity was 640 MB of SDRAM (though depending on the motherboard the capacity limit could have other values, e.g. 512 MB or 768 MB were other frequent values). Only around 2003, motherboards where you could install up to 4 GB of DDR memory became widespread. I had a few such motherboards, with Pentium III "Coppermine" and with AMD Athlon "Thunderbird" (with 3 DIMM sockets, 2 accepting 256 MB modules and 1 accepting 128 MB modules). While I had initially equipped them with less memory, i.e. either 128 MB or 256 MB, because of the high cost at that time, eventually I had maxed up the installed memory to 640 MB on the Athlon motherboards. At that time, the memory controller was not included in the CPU, but it was contained in an external chip, the Northbridge. The MB chipsets could come from various vendors, including Intel and Via. Depending on the chipset, different maximum amounts of SDRAM could be supported. Sometimes there were also limits for the maximum amount of RAM caused by the L2 cache controller, due to the size of the tags required in cache lines. Even with the same chipset, the MB manufacturer could choose to route different numbers of address lines to the sockets, probably depending on whether the extra capacitive loading caused by a bigger memory module would have allowed it to function at the rated speed on that PCB. 64 MB would have been a typical maximum memory around 1998 (2 sockets for 32 MB SDRAM modules, on a MB with an AGP socket for the graphics card), so if the author would have had that year in mind, you would be right.

LargoLasskhyfv 1y ago
I had 1.5GB (3 x 512MB) Virtual Channel Memory (SDRAM) on a T-Bird. https://en.wikipedia.org/wiki/Synchronous_dynamic_random-access_memory#Virtual_channel_memory_(VCM)_SDRAM https://en.wikipedia.org/wiki/Synchronous_dynamic_random-acc... Undervolted and OC'd to 1800+ under Linux, 2100+ under NetBSD. Stable and rock-solid :-)

DonHopkins 1y ago

Haven't you ever heard the Bill Gates quote that he didn't actually say? https://news.ycombinator.com/item?id=18120477 https://news.ycombinator.com/item?id=18120477 https://groups.google.com/g/alt.folklore.computers/c/mpjS-h4jpD8/m/9DW_VQVLzpkJ https://groups.google.com/g/alt.folklore.computers/c/mpjS-h4... QUESTION: I read in a newspaper that in 1981 you said, ``640K of memory should be enough for anybody.'' What did you mean when you said this? ANSWER: I've said some stupid things and some wrong things, but not that. No one involved in computers would ever say that a certain amount of memory is enough for all time. The need for memory increases as computers get more potent and software gets more powerful. In fact, every couple of years the amount of memory address space needed to run whatever software is mainstream at the time just about doubles. This is well-known. When IBM introduced its PC in 1981, many people attacked Microsoft for its role. These critics said that 8-bit computers, which had 64K of address space, would last forever. They said we were wastefully throwing out great 8-bit programming by moving the world toward 16-bit computers. We at Microsoft disagreed. We knew that even 16-bit computers, which had 640K of available address space, would be adequate for only four or five years. (The IBM PC had 1 megabyte of logical address space. But 384K of this was assigned to special purposes, leaving 640K of memory available. That's where the now-infamous ``640K barrier'' came from.) A few years later, Microsoft was a big fan of Intel's 386 microprocessor chip, which gave computers a 32-bit address space. Modern operating systems can now take advantage of that seemingly vast potential memory. But even 32 bits of address space won't prove adequate as time goes on. Meanwhile, I keep bumping into that silly quotation attributed to me that says 640K of memory is enough. There's never a citation; the quotation just floats like a rumor, repeated again and again.