Jesus, for a moment I thought who edited those loud beep noises into the video. Turns out something was burning in the kitchen and the smoke detector caught it.
While nearly all PCs had motherboards, there were a few with passive backplanes with the processor and memory on an expansion card. Most backplanes have address decoding logic in each card, but some had pre-decoded select signals like the Apple II and the NuBus. That makes the boards cheaper and allows you to put in two identical boards without having to configure them but limits how many boards a system can have (I once built a PC with 72 slots, for example).
Back in the early 70s I was a service tech for NCR Century series mainframes. The backplane on those mainframes was wire wrapped. Sounds kinky but it made for easy troubleshooting, lots of pins to hang scope probes on.
For Windows computers, to see what addresses are being assigned to your hardware: Right-click the Start button > System > in the left sidebar, Device Manager > pick a low-level device (ex "IDE ATA/ATAPI controllers > SATA AHCI Controller", or a few things under System devices) > Resources tab > in the upper box ("Resource settings"), scroll down to "Memory Range"
I'd like to see the modern PC motherboard compared & contrasted with the classic backplane system. Or what about smartphones? Supercomputers? Industrial robots?
Information from a cpu when executed is addressed in bytes, which are stored on binary addresses(memory address) which transmits through a data bus to communicate with various pieces of hardware. Computer Connections are influenced mainly by the Operating System Kernel which is responsible for managing computer resources and allocating the memory address.
With IBM compatible PCs, there was actually a time when much more stuff sat on (e)ISA or VLB or PCI extension cards. For example, my first 386 had an ISA card for the hard disk controller and for the graphics card, and then I upgraded it with 2 more cards, one was a sound card, the other was a CD-ROM drive controller card. The next generation of PCs included the IDE hard disk and CD-ROM controllers on the motherboard, but the graphics card, sound card and network card were still cards on the VLB or PCI bus. Later on, the sound card wandered onto the motherboard as well, as did the network card. And a bit later, even the graphics card got there. So now there is a motherboard which has 4 functions integrated that were separate before. I think this trend will continue as well.
I always kind of thought of the input/output versus memory signal line like an additional addressing bit. It's not quite that, because when you're programming, you have to use IN and OUT instructions, and a particular processor may only use some subset of the address lines to address I/O (for example, only the lowest 8 bits or the lowest 16 bits). The idea of decoding is exactly the same with this extra bit, the IO/MEM "address" bit needs to be (say) high, as well as all the other addressing bits to be in the proper pattern, for the peripheral to respond. Then there's other styles of processors (68000 series, the 6502, and others) which don't have any separate I/O instructions, the peripherals are accessed the same way as memory. It's like they don't have that extra IO/MEM bit.
23 bits of address space, on a 16 bit machine. so we have (2^23) addresses and each address can handle 16 bits or 2 bytes, so total number of values is (2^23)*16 bits = (2^23)*2 bytes = (2^24) bytes = 16777216 bytes. EDIT: corrected a typo
It is worth clarifying buses handle words, not bytes. 68k has 23 address lines for 16-bit words, so it covers 2^24 bytes or 16MB. Internally the processor uses 24 bits to access individual bytes, but only 23 "wires" (called A23-A1) are used as shown in the schematic, because 2 bytes are put on the bus at the same time, and depending on the memory access one or both will be taken (implicit A0).
That is kind of interesting. I always thought that IRQs did this type function (SUN could have been custom, etc though). I have dealt with a few backplanes, but my case they mounted SCSI HDDs for connection into the SCSI bus then the RAID controller. In a case like that backplane with SCSI it assigned SCSI I.Ds to the drives based on the slot they got put in. The addresses he is talking about and how it is segmented kind of makes me think of the network, host, subnet mask used in I.P networking. I don't know how it works, but I know in Cisco switches if you have to reset the password, etc you have to change what is called a configuration register. I think the value varies by model but somehow when you change the config register it then points to a place in the config that skips the password lines, etc. I always assumed that value was a memory address, but I don't know. I think on the catalyst 2960 it was 0x2902 and 0x2904 (or something like that).
You probably don't want to put the ROM in anywhere else except for the lowest addresses (ie. Z80 started executing instructions from 0x0) or quite possibly the topmost ones, depending on the architecture.
tesla. py There are many different system buses; for that Sun machine it would be VME, but you've likely heard of ISA and PCI, which operate similarly. AMBA and Wishbone are other examples typically used inside system on chip architectures. Frequently they were designed for a particular processor in the first place, tying VME to 68000 and VLB to 486. I²C was designed for much slower and smaller control interfaces, such as for TV tuners, but is reused in many places including SMBus. For instance, modern PCs use a I²C bus to identify memory modules, storing information on how to set up the DDR3 or similar buses.
Great video! You might want to be careful about how you use the word "bit" in future videos. Sometimes you use "bit" to refer to a binary bit while other times you use it to refer to a chunk of something and as such it's not always immediately obvious to which you're referring.
Hey Compterphile, I heard a lot about HPs "The Machine" over the last few months. Can you please make a video and compare The Machine to traditional computers?
So why don't all PCs today use the backplate system with the main cards preinstalled? I feel like it would be much easier to get into custom PC building if your CPU came on its own card like this instead of having to remove the heatsink, remove the old thermal paste, undo the clips, replace the CPU...
Too big. Swappable components are always larger than integrated ones. On top of that, some components like the CPU and memory require more bandwidth than is feasible on a shared bus. If the CPU came on it's own component, it would pretty much be as complex as the motherboard itself, so you're essentially installing 2 motherboards.
if you can, go with electronics... then move to germany
7 лет назад
Well, I'm doing a B.sc. in electronics and computer science at the moment. No need to choose one. :D Also, robotics engineering is a bit of both, with some mechanics mixed in as well.
This is related to IRQs and DMA. IRQ solve the problem of "Hey CPU, here is your network card and I just received data". This aspect isn't mentioned in the video. IRQs in PCs are much less of a hassle now. Since around 2003 message signaled interrupts were introduced. en.wikipedia.org/wiki/Message_Signaled_Interrupts These allow for many more interrupts and make troublesome interrupt sharing a thing of the past. Typically a card does a DMA transfer and then generates a MSI. PCI does not have a single DMA controller as PCI allows for bus masters.
DMA effectively requires something called a DMA-controller aka bus-controller, with it, multiple devices may request access to the bus, then be allowed to access another device on the system. This means a GPU can request RAM-access or access to another GPU. DMA isn't required for a backbone-based-system, it wasn't used for example on the Altair and its clones.
You poor Brits. It must drive you crazy when the prof. uses "bit" to mean "part" or "piece" in the same sentence that he uses "bit" to mean the bits in a byte or word. In the US, we would use "this part" or "this section" but certainly not "this bit" when were are talking about multiple bits in a byte or word.
I thought they were getting political right from the get-go, naming that server after the Sheriff of Nottingham. ETA: Hey, 12th century politics is still politics.
2:22 Strong and Stable propaganda ;-) Remember to vote you lot in the UK. 9:44 might confuse non-native English speakers. (Binary numbers take up... (more space than hexadecimal numbers.))
Jesus, for a moment I thought who edited those loud beep noises into the video.
Turns out something was burning in the kitchen and the smoke detector caught it.
Area codes in the UK are known as STD codes? That gives a whole new meaning to that Ludacris song.
While nearly all PCs had motherboards, there were a few with passive backplanes with the processor and memory on an expansion card. Most backplanes have address decoding logic in each card, but some had pre-decoded select signals like the Apple II and the NuBus. That makes the boards cheaper and allows you to put in two identical boards without having to configure them but limits how many boards a system can have (I once built a PC with 72 slots, for example).
Back in the early 70s I was a service tech for NCR Century series mainframes. The backplane on those mainframes was wire wrapped. Sounds kinky but it made for easy troubleshooting, lots of pins to hang scope probes on.
Brilliant! Really demystifying the world of electronics! THANK YOU!!!
For Windows computers, to see what addresses are being assigned to your hardware:
Right-click the Start button
> System
> in the left sidebar, Device Manager
> pick a low-level device (ex "IDE ATA/ATAPI controllers > SATA AHCI Controller", or a few things under System devices)
> Resources tab
> in the upper box ("Resource settings"), scroll down to "Memory Range"
I'd like to see the modern PC motherboard compared & contrasted with the classic backplane system. Or what about smartphones? Supercomputers? Industrial robots?
You are really blue skying this
Information from a cpu when executed is addressed in bytes, which are stored on binary addresses(memory address) which transmits through a data bus to communicate with various pieces of hardware. Computer Connections are influenced mainly by the Operating System Kernel which is responsible for managing computer resources and allocating the memory address.
2:22 "strong and stable" ..... popular thing to say lately ;-)
Good video, thanks!
Vote Acorn 2017
Way to avoid Tory funding cuts!
Ireneusz Zielinski 😂 I went to comment saying the same thing :)
Took the words right out of my mouth!
Beat me to it!
Thank you for clearing up my confusion... Great video! 👍👌
I love this guy. I wish I could find someone like him.
With IBM compatible PCs, there was actually a time when much more stuff sat on (e)ISA or VLB or PCI extension cards. For example, my first 386 had an ISA card for the hard disk controller and for the graphics card, and then I upgraded it with 2 more cards, one was a sound card, the other was a CD-ROM drive controller card. The next generation of PCs included the IDE hard disk and CD-ROM controllers on the motherboard, but the graphics card, sound card and network card were still cards on the VLB or PCI bus. Later on, the sound card wandered onto the motherboard as well, as did the network card. And a bit later, even the graphics card got there. So now there is a motherboard which has 4 functions integrated that were separate before. I think this trend will continue as well.
5:33 and so on i get lost, what Wikipedia page or any book can i read to understand all that ?
Kept getting distracted by the little white/blue toy computer in the background. What is that?
Is that an Amiga A1000 in the background to the right ?
I always kind of thought of the input/output versus memory signal line like an additional addressing bit. It's not quite that, because when you're programming, you have to use IN and OUT instructions, and a particular processor may only use some subset of the address lines to address I/O (for example, only the lowest 8 bits or the lowest 16 bits). The idea of decoding is exactly the same with this extra bit, the IO/MEM "address" bit needs to be (say) high, as well as all the other addressing bits to be in the proper pattern, for the peripheral to respond.
Then there's other styles of processors (68000 series, the 6502, and others) which don't have any separate I/O instructions, the peripherals are accessed the same way as memory. It's like they don't have that extra IO/MEM bit.
How does bus works on multi cpu systems?
Thank you.
Now I understand why different OS support different counts of CPUs.
Bill Kang
I don't see a reply. What did they reply? I'm curious.
They finally used a tripod! Finally, stable footage.
At 5:45 : why is 23 bits equal to 16,777,216 bytes? Wouldn't 2^23 be 8,388,608 bits or 1,048,576 bytes?
The adressing is always based on bytes, not bits.
The 16.7M thing is also 24 bit, not 23.
68k data bus width is 16 bits, so you have two bytes per address. 2*2^23=16777216 bytes.
Ohh, alright. Thanks, I know nothing about hardware.
23 bits of address space, on a 16 bit machine. so we have (2^23) addresses and each address can handle 16 bits or 2 bytes, so total number of values is (2^23)*16 bits = (2^23)*2 bytes = (2^24) bytes = 16777216 bytes. EDIT: corrected a typo
It is worth clarifying buses handle words, not bytes. 68k has 23 address lines for 16-bit words, so it
covers 2^24 bytes or 16MB. Internally the processor uses 24 bits to access individual bytes, but only 23 "wires" (called A23-A1) are used as shown in the schematic, because 2 bytes are put on the bus at the same
time, and depending on the memory access one or both will be taken (implicit A0).
That is kind of interesting. I always thought that IRQs did this type function (SUN could have been custom, etc though).
I have dealt with a few backplanes, but my case they mounted SCSI HDDs for connection into the SCSI bus then the RAID controller. In a case like that backplane with SCSI it assigned SCSI I.Ds to the drives based on the slot they got put in.
The addresses he is talking about and how it is segmented kind of makes me think of the network, host, subnet mask used in I.P networking. I don't know how it works, but I know in Cisco switches if you have to reset the password, etc you have to change what is called a configuration register. I think the value varies by model but somehow when you change the config register it then points to a place in the config that skips the password lines, etc. I always assumed that value was a memory address, but I don't know. I think on the catalyst 2960 it was 0x2902 and 0x2904 (or something like that).
Another cool video, gonna watch it right away
Great hardware and an awesome explanation. Thank you!
I would like my phone number to have no STDs, thank you very much.
I know a person whose spouse cheats on so much, even their phone number's got an STD
You probably don't want to put the ROM in anywhere else except for the lowest addresses (ie. Z80 started executing instructions from 0x0) or quite possibly the topmost ones, depending on the architecture.
spaqin it doesn’t really matter as long as there is only ram and empty space before. There is nothing to read there anyway.
on the data and address buses are they communicating over i2c ?
if not i want the name of the protocol to read about it.
tesla. py There are many different system buses; for that Sun machine it would be VME, but you've likely heard of ISA and PCI, which operate similarly. AMBA and Wishbone are other examples typically used inside system on chip architectures. Frequently they were designed for a particular processor in the first place, tying VME to 68000 and VLB to 486. I²C was designed for much slower and smaller control interfaces, such as for TV tuners, but is reused in many places including SMBus. For instance, modern PCs use a I²C bus to identify memory modules, storing information on how to set up the DDR3 or similar buses.
Great video! You might want to be careful about how you use the word "bit" in future videos. Sometimes you use "bit" to refer to a binary bit while other times you use it to refer to a chunk of something and as such it's not always immediately obvious to which you're referring.
2:22 "Which would make sure you've got a *strong and stable* signal..."
Computerphile going political confirmed.
Make Acorn Great Again (I'll get my coat).
The statement is false so fits politics well.
EdMcF1 give by
I think you can do the address matching logic with xnor gates looking at groups of two bits
Dr bagley is my favorite person :)
Is this the same as the IRQ system?
081 811 8181 (yeah) was Going Live era, which then evolved to 0181 811 8181 (yeah) during the Live & Kicking era
Hey Compterphile, I heard a lot about HPs "The Machine" over the last few months. Can you please make a video and compare The Machine to traditional computers?
So why don't all PCs today use the backplate system with the main cards preinstalled? I feel like it would be much easier to get into custom PC building if your CPU came on its own card like this instead of having to remove the heatsink, remove the old thermal paste, undo the clips, replace the CPU...
kiefac motherboard looks "cooler"?
Too big.
Swappable components are always larger than integrated ones. On top of that, some components like the CPU and memory require more bandwidth than is feasible on a shared bus.
If the CPU came on it's own component, it would pretty much be as complex as the motherboard itself, so you're essentially installing 2 motherboards.
will you guys turn on the sun system server?
Well, they did turn it on in the earlier video but it currently doesn't fully boot up yet. Gets to the diagnostics but doesn't pass them and stops.
KlaxonCow yeah, i mean boot into it's native OS
How's a first year student supposed to choose between computer science and electronics?! They're all too much fun :'(
if you can, go with electronics... then move to germany
Well, I'm doing a B.sc. in electronics and computer science at the moment. No need to choose one. :D
Also, robotics engineering is a bit of both, with some mechanics mixed in as well.
Robotics is the one. We are on the cusp of the robotic age.
Mikkel Højbak US now has degrees like Computer Engineering. It's a hybrid of the two.
Great upload!
That computer's name is "sherriff". At Nottingham U. Awesome!
omg is that an ibm 8088?
Is this also related to IRQ and DMA? I remember fiddling around with that when I was a kid. It was a nightmare :P
This is related to IRQs and DMA. IRQ solve the problem of "Hey CPU, here is your network card and I just received data". This aspect isn't mentioned in the video.
IRQs in PCs are much less of a hassle now. Since around 2003 message signaled interrupts were introduced.
en.wikipedia.org/wiki/Message_Signaled_Interrupts
These allow for many more interrupts and make troublesome interrupt sharing a thing of the past.
Typically a card does a DMA transfer and then generates a MSI. PCI does not have a single DMA controller as PCI allows for bus masters.
DMA effectively requires something called a DMA-controller aka bus-controller, with it, multiple devices may request access to the bus, then be allowed to access another device on the system. This means a GPU can request RAM-access or access to another GPU. DMA isn't required for a backbone-based-system, it wasn't used for example on the Altair and its clones.
Interesting. I've often wondered how the backplane works.
soo, it just works like a KNX System?
The 68000 was a weird but awesome CPU.
10:00 Nybble, not a bit :p
Just loook at the size of that 6800 chip!
strong and stable signal
how to improve our PC memory and processing speed
Ha "strong and stable". I challenge computerphile to use the term "extreme vetting" in your next video
Honestly I had problem to understand when Dr Bagley uses the word "this bit"...to point at a set of bits.
Really confusing :)
Maybe he said "this byte"?
Probably :)
But can it play crysis?
Not first, guess I better watch the video.
I would lose my mind if I had to enter addresses manually when I built my computer
this is the guy who likes to live dangerously :D
Make strong and stable great again.
I learned a bunch of this by working through nand2tetris! :D
do i have to understand what hes saying
HAHA
Douglas Adams would love that address ;)
You poor Brits. It must drive you crazy when the prof. uses "bit" to mean "part" or "piece" in the same sentence that he uses "bit" to mean the bits in a byte or word. In the US, we would use "this part" or "this section" but certainly not "this bit" when were are talking about multiple bits in a byte or word.
Nice.
Please don't use that goosebumps-marker anymore!! T^T
4096 DEC = 1000 HEX
I thought they were getting political right from the get-go, naming that server after the Sheriff of Nottingham.
ETA: Hey, 12th century politics is still politics.
2:22 Strong and Stable propaganda ;-) Remember to vote you lot in the UK. 9:44 might confuse non-native English speakers. (Binary numbers take up... (more space than hexadecimal numbers.))
Whats on STD code address A1D5 ?
late to the notification :D
Shoot. Not first. I see Dr. Steve in the thumbnail though, so this ought to be good.
moist
Aaro Perämaa Eww
Sun servers break constantly, basically junk.
Squad, ASSEMBLE!
"CPU Card"
.
Second
So cringey.
first