I have a question.

[Marks256]

Hi. I am a highschool student(sophmore) in minnesota. I guess since this is my first post, i might as well give you people a little info about me, then i will get the my problem. Ok, my best friend(let's call him Fred, although that isn't his real name) introduced me to programming in sixth grade. He went to a summer program being held at a local college, called "College for Kids". He took a class there about QBasic. When he was done, he brought his disk home, i copied it, several times. As of right now, we have pritty much mastered QBasic(and not how to spell). In about 7th grade, he introduced me to electronics. That year my parrents bought me a electronics learning lab. I still havn't finished it, because the examples were too boaring! So, i kinda set off on my own, and started discovering things on my own. I am by no means an expirianced electronics person. This is why i came to this website. I hope this forum will teach me what i need to know about electronics. I would like to go to college for Computer Engineering, but there is alot i need to learn before then, so, here is my first problem:

Fred and I would like to build a computer. Just a simple little computer built off of an 8088, 8086, or i486 processer. We would like to know were we should start. We both have very basic ideas on how computers work. Also, if this matters, we are both Computer Techs at our school, so we do know how to work on PC's, but not build one from the ground up! Were should we start? I am going to get a book on ebay this weekend about how the 8088, 8086, and the i486 work, how to program, etc. What else(i don't have a job, so i am short on cash...)?

 

[srimannarayanakarthik]

hi

u r tellin tat u r running short of money.its ok then search for a free e book,there are a lot many books avaliable online. then u need to undertand the architecture of the microcontroller which u rusing and the programming language.then u need to know how to make the logic to get the deired output. this i long way ahead. jut tart with ur basics. learn the architectre and workin

 

[dknguyen]

I would start with a PIC or something instead of a full-sized computer processor. I'm not sure how complicated an 8086 or 486 processor is, but I know the procesors today are almost hopeless for most people to implement...I'm not sure of the software issues involved with making a PC from scratch (unless you are talking about just getting all the parts and sticking them into a tower). But if you mean designing the motherboard...that's far from easy to do, even for a veteran.

 

[AllVol]

Start with a PIC. In most cases, their cost will not wreck your budget (Microchip even has a few samples. Check their website.) I would suggest the 16F877, for which there is plenty of help, advice and instruction available on the 'net. By the time you get a couple of boards built and gather your compiler, programmer, etc. (again mostly free or demo stuff) it will be time for school again.

Luck,
AllVol

 

[Paul Obrien]

If you can find a copy "The 8088 Cookbook" will provide all that you need to know about 8088s. It has been out of print for a long time >10years so don't bother going to Amazon. If you do find a copy and still want to proceed be warned it is a lot more expensive than using a microcontrollers as there are numerous support ICs and EPROMs to worry about.

 

[philba]

If you just want to build something that is programmable, then go for the pic and stop reading. However, if your goal is to get deeper into how computers really work, then read on...

I'd spend some time getting a good understanding of the basics of computer organization: cpu, memory, busses, peripherals and so on. Many moons ago I took a grad school course (CS) on computer organization. The text was pretty good for the time - Computer Architecture, iirc. I'm sure there must be something similar if it's not available.

if you live near a large city, they must have PC recycle places. Often you will find older computers that you can gut for parts. an 8088 or 8086 is pretty easy to interface to. bg micro **broken link removed** carries the chip and peripherals. the 88 is nice because you can use byte-wide memory (vs 16 or 32 bit wide) and it's fairly forgiving on timing and such. the 486s and up run wicked fast and require very careful design to get working correctly. also, there are lots of tools for the 88 out there.

 

[Hero999]

Buildingcomputers is easy, just buy a mother board, case, PSU, hard disk, RAM, CD/DVD RW, keyboard, mouse and monitor, plug them all together, install a suitable operating system and you have a fully-working custom-built PC!

 

[Marks256]

I wan't to design the mobo, and the components. I all-ready have mastered building PC's from the allready manufactured MoBo's, CPU's, ETC. I would like to build a computer from scratch. I will philba said. I will read about the components, and how they work. If i have any questions, i will post them here. I really apreciate the help, exept for hero999's advice. Also, Hero999, i said i was short on cash, because i spent all my $$ on my custom made computer(built from the ground up by me). Here are the specs:

AMD Sempron 2800+ (1.6ghz)
nFORCE3-A MoBo w/ 1.6ghz HT FSB
512mb of DDR400 Kingston RAM
AGP 8x
8 USB 2.0
DVD-ROM
CD-RW 52x32x52
nVIDIA GeFORCE 4000
C-MEDIA 5.1 surround-sound sound card
Windows XP PRO w/ sp2
350watt powersupply
Shall i go on?

 

[Hayato]

I wan't to design the mobo, and the components. I all-ready have mastered building PC's from the allready manufactured MoBo's, CPU's, ETC. I would like to build a computer from scratch. I will philba said. I will read about the components, and how they work. If i have any questions, i will post them here. I really apreciate the help, exept for hero999's advice. Also, Hero999, i said i was short on cash, because i spent all my $$ on my custom made computer(built from the ground up by me). Here are the specs:

AMD Sempron 2800+ (1.6ghz)
nFORCE3-A MoBo w/ 1.6ghz HT FSB
512mb of DDR400 Kingston RAM
AGP 8x
8 USB 2.0
DVD-ROM
CD-RW 52x32x52
nVIDIA GeFORCE 4000
C-MEDIA 5.1 surround-sound sound card
Windows XP PRO w/ sp2
350watt powersupply
Shall i go on?

I did not understand why did you place your computer specs here.
You want to build a computer from scratch, similar to your sempron 2800+ (1600 Mhz)? Using 8088 (2MHz) /8086 (10 MHz)?

Or you want to build a simple computer, like a calculator?

Define better what do you mean by saying "scratch":

1 - You want to build all components (like mems, processors, the north/south bridge, the storage devices...), so you gonna create your own computer standards (like Apple/PC standards).

2 - You want to use comercial components, like components from VIA/SiS/NForce/ATI/INTEL to build the mobo, memories, etc. You gonna use a comercial processor, storage devices...?

Well, the basic queistions are:
Do you have enough electronics knowledge and experience?
Do you know Assembly?
Do you know how digital devices works?
Do you know the computer theory?
Do you have the necessary machinery to assemble the components, the PCBs...?
Do you have the necessary equipaments to test the computer components (Logic Analyzer, Oscilloscope...)?
Do you have enough money and time to spend, designing the computer?
Do you have enough pacience to withstand the failures?

 

[Paul Obrien]

If you want to get to know how computers work, then microcontrollers take most out the design work out of the loop, you can still add memory, IDE drives and create an operating system on many cheap controllers and still have a lot of support in forums and websites, I think the homebrewed 8088,86 is nearly an orphan.. Just google 8088 computer, there aren't to many groups supporting it, any groups usually deal with the XT or AT.

 

[Marks256]

I did not understand why did you place your computer specs here.
You want to build a computer from scratch, similar to your sempron 2800+ (1600 Mhz)? Using 8088 (2MHz) /8086 (10 MHz)?

GOD NO! That would be suicide! I was just showing Hero999 that i did make a system from pre-manufactured parts.

Define better what do you mean by saying "scratch":

I want to build a fully functioning system around the 8088/8086(havn't decided witch one qite yet). I just want to learn how a computer works, and see if i can build one too. I want to build the circuitry to the RAM, Boot ROM, ETC. Then keep building things up on it, just to see if i can. If we can get it to work, we will also try to put an IDE Drive on it too.

1 - You want to build all components (like mems, processors, the north/south bridge, the storage devices...), so you gonna create your own computer standards (like Apple/PC standards).

Yes. I couldn't have said it better my self. I won't build the processor yet. I will save that task for when i finish this one! I will build up the system arround one of the two processors.

2 - You want to use comercial components, like components from VIA/SiS/NForce/ATI/INTEL to build the mobo, memories, etc. You gonna use a comercial processor, storage devices...?

Kinda. I will just use the processer, then buy a crap load of components from Jameco.

Do you have enough electronics knowledge and experience?

I'm not sure. If not, then this will be a fun learning experiance. I guess this will give me a chance to learn what i may not allready know.

Do you know Assembly?

No. It is fully explained in one of the books i am going to purchase this weekend.

Do you know how digital devices works?

I know how digital works, but i don't have every chip memorized. If i have any questions, i will post.

Do you know the computer theory?

Ahh, no. What is that? Chances are i do, but i don't recall it at the moment. Will you leave a small description?

Do you have the necessary machinery to assemble the components, the PCBs...?

Not off hand. I will get them within due time, though.

Do you have the necessary equipaments to test the computer components (Logic Analyzer, Oscilloscope...)?

I am in the middle of finishing my homebrewed Logic Analyser, i just need to write the software. I do not have an Oscilloscope, but, if i can get a job next year, it will be on my very, very long list of things i need.

Do you have enough money and time to spend, designing the computer?

MONEY: No. I will just through in some when i get cash. I have alot of components i can desolder.
Time: I don't plan on finishing it in a year or two. I just want to get it done by time i get to college. It might look good on an application....

Do you have enough pacience to withstand the failures?

I don't know. I guess we will find out, wont we?



I do not want to use a microcontroller. Then it wouldn't be a true computer. I dont care how hard it is goning to be. If i need help, you guys/girls are here for me, right? Don't worry. I will do my "Homework. I will do research whenever possable.

I have another question. I read about how the CPU works, and i understand that. I also now understand how RAM works. What do i use for the chipsets? The thing that connects the RAM, and all the other devices to the CPU? Is there one chip, or will i have to make that too?

 

[dknguyen]

I'd take it slow (possibly very slow). THis sounds just like the 4rth year design project for the Computer Engineering department at my university.

I do not want to use a microcontroller. Then it wouldn't be a true computer.

True computer? I think you mean true PC (don't diss microcontrollers!). Just because it's embedded or something that is not sitting on a desk with a monitor and keyboard doesn't mean it's not a computer! That thing sitting behind your eyes is a computer that kicks the ass of every manmade computer on the planet.

As for your last question about connecting up the RAM and chipsets, I think you have to read the manuals and datasheets about the processor you intend to use and find out how it interfaces with memory and periphreals. Those tend to be very device specific.

 

[Nigel Goodwin]

I really apreciate the help, exept for hero999's advice. Also, Hero999, i said i was short on cash, because i spent all my $$ on my custom made computer(built from the ground up by me).

I agree with Hero999!, you say you're short of cash?, but then you're wanting to undertake a fairly pointless expensive project - I don't think you realise how much money (and time) something like this is going to take!, assuming you ever manage it at all?.

 

[Marks256]

I DO NOT THINK THIS WILL BE A POINTLESS PROJECT! My favourite saying is "An education is worth more than any sum of money"! I would rather save $400 now on learning about this stuff, than have to spend $5000 later for college. The more i can cram into my head now, the more money it should save later(schollerships!).

I am not dissing Microcontrollers. I love microcontrollers myself! I mean, microcontrollers are pritty much a simple computer, shoved into a small IC. A processer is just the processer. I just wan't to use a processer, not a microcontroller. Besides, a processer would look cooler, because there would need to be more things hooked up to it....

 

[zevon8]

At the risk of sounding like a wet blanket, ignorance is bliss.

I applaud your drive and enthusiasm, but you should really lean to crawl across the room before you decide to plan a mission to Mars. There are so many interdependant technologies and disciplines involved in what you want to do, none of which you can "pick-up" over the week-end from an old book bought off of EBay.

Take a course in basic electronics, buy some books. Talk to some electronic engineering university students. I think you will be amazed and/or humbled by what is required for such an undertaking.

Can you design a multilayer PCB? Do you understand the significance of trace length relative to signal timing? What is propagation delay? Can you solder surface mount components?

I would rather see you try something that you have a hope in achieving, and learn from it, than try something you cannot accomplish, and walk away discouraged.

 

[Nigel Goodwin]

I DO NOT THINK THIS WILL BE A POINTLESS PROJECT! My favourite saying is "An education is worth more than any sum of money"! I would rather save $400 now on learning about this stuff, than have to spend $5000 later for college.

I would expect you to spend considerably more than $400, you don't appear to have any idea of the complexity of the task?. On the software side alone, are you capable of writing machine code to create an OS and BIOS?. Bear in mind as you've got to design and build BOTH the hardware and software, it's extremely difficult to fault find, as you don't know where the problem lies!.

I would suggest you start somewhat lower?, perhaps a 6502 or Z80?, something more back in the "build from scratch" days. An 8088 or 8086 probably isn't too bad?, but a 486 is asking for trouble!.

 

[Marks256]

Ok, now you people are trying to discourage me! I don't like it. If i have to i will go find a more supportive forum community. I knew if i posted how old i was, all you people would do is try to talk me out of it. So what if i don't know the relationship between the clock and trace length? I will learn about it if i need to. This is what is wrong with society today! People have no faith in people. Back to may age. The whole reason i came to this forum, is becaused i googled "Homebrew Computer". I clicked on the link, and it came to one of the treads, similar to the one i posted now. Guess what? The responses were endless! People helped in any way possable, NOT trying to talk the poster out of making it. I expected the same response, but NO! You people are so set on thinking that since i am "nothing but an ingnorint highshool studend wasting his time on something that is not achievable for his age", that i don't have a chance in hell of compleeting this task. How do you expect me to learn, if i don't try? Huh? So maybe i am "Jumping the gun", but i didn't know of any simpler processer to build arround. Perhaps if i find something on another processer, i will give it a shot! But i would REALLY apreciate it if you people would be more supportive. Since nobody will help me, i will just start on my own. If the book i get is truly worthless, then that is my problem. But if it helps, and i am able to get somewere, then i say; maybe the younger generation is alot more capable than you would imagine.

 

[Nigel Goodwin]

I think we all feel you're starting too big? - if you start swimming you begin in a small pool, and work up, you don't jump in the sea and try to swim to the next land mass! - I think you would drown in the first few minutes?.

Try posting a very brief list of the facilities you want to achieve in the first phase of your project, then a list of what you want to add in the future.

 

[Hayato]

Ok, now you people are trying to discourage me! I don't like it. If i have to i will go find a more supportive forum community. I knew if i posted how old i was, all you people would do is try to talk me out of it. So what if i don't know the relationship between the clock and trace length? I will learn about it if i need to. This is what is wrong with society today! People have no faith in people. Back to may age. The whole reason i came to this forum, is becaused i googled "Homebrew Computer". I clicked on the link, and it came to one of the treads, similar to the one i posted now. Guess what? The responses were endless! People helped in any way possable, NOT trying to talk the poster out of making it. I expected the same response, but NO! You people are so set on thinking that since i am "nothing but an ingnorint highshool studend wasting his time on something that is not achievable for his age", that i don't have a chance in hell of compleeting this task. How do you expect me to learn, if i don't try? Huh? So maybe i am "Jumping the gun", but i didn't know of any simpler processer to build arround. Perhaps if i find something on another processer, i will give it a shot! But i would REALLY apreciate it if you people would be more supportive. Since nobody will help me, i will just start on my own. If the book i get is truly worthless, then that is my problem. But if it helps, and i am able to get somewere, then i say; maybe the younger generation is alot more capable than you would imagine.

Well, nobody here is trying to discourage you. We are saying that it is something very very difficult and inviable to do in our backyards. Just it.

Don't be such paranoid, nobody here cares to age, but to maturity of ideas.

It's not by buying a book that you'll leard how to build a homebrew computer. The Theory is nothing comparated to The Practice.

Everybody that has a minimum electronics knowledge knows that a Hartley Oscillator is made by a 2 inductors and a capacitor, plus the active component. But if they are asked to build or project one Hartley Oscillator, they will not success.
Why? Lot of theory and lack of practice.

As it was said before, you are trying to fly before you are able to even walk. Computer are very complex apparatus, you MUST learn the basic of the basic, then leard the basic, then learn the intermediate, then learn the advanced and then learn the post-advanced.
You are trying to jump from the basic of the baisc to the post-advanced.

Are you able to do something in digital electronics? Or even in traditional electronics? Without looking on someone else made schemactics?

Want to make a test?
Make a schematic for me, DECIMAL to BCD converter, just using simple logic.

Do you know what is pig capacitance or pig inductance?

Do you know how high frequencies behaves in PCB trails? And in a round conductor, like a wire?

Do you know what is impedance?

Do you know what is a baud rate?

Do you know what is modulation? And what kinds of modulation?

Do you know how electronic memory works?

Do you know how a memory stack works?

Are you able to make a microcontroller program from scratch?

Ask your self those questions, and more. If you are not able to answer that all by yourself, then you have a problem.

Before you make your homebrew computer, you MUST MASTER the electronics skills.

And we are supportive, if we weren't we would totally encourage you to build a computer, without showing the "real side" of the thing.

 

[Marks256]

OK. I guess i am jumping the gun. I will now ask for help; Where should i start?

Do you know what is pig capacitance or pig inductance?

Not a clue.

Do you know how high frequencies behaves in PCB trails? And in a round conductor, like a wire?

I think i experience this once. Doesn't it act like an antenna? Producing noise?

Do you know what is impedance?

nope.

Do you know what is a baud rate?

This i do know. Baud rate is bytes/sec.

Do you know what is modulation? And what kinds of modulation?

oh god! I don't know this one either!

Do you know how electronic memory works?

Sort of...

Do you know how a memory stack works?

Not sure?

Are you able to make a microcontroller program from scratch?

[starting to cry;] NO!


Ok. I do need help. Where should i start? I have two books on Analog and Digital electronics. I will read through them, and do all of the examples. Then what? I am heading to the library now....