so i have been wasting my time for a long time now , and i managed to design a system that outputs 480*224 resolution and that can output colored bitmaps and a low form of video using a couple of AVRs and a dual-port sram chip . this got me thinking , so if i get some higher level chips and start designing some proper PCBs , is it possible for me to get to get a working computer on my own ? if i can control a high level processor on my own i can , but can it even be done ?
all i can use is chips and software written by me, so i need to start with chips (of any kind) and then design a computer with decent capabilities . ?? can that be done ?? or is it silly to even consider this ?? .. (i want to do this for myself , not for any useful purposes)
It depends how you define "from scratch".
In the early 70s before cheap microprocessors, there were published designs for TTL home computers.
I don't think I'd like to go lower than TTL.
Today, you could fit dozens or hundreds of 6502-equivalent processors on a single FPGA.
It's been done before, so it depends entirely on your skill, knowledge and effort you are willing to put into it, and how you define "decent capabilities"? Playing Crysis 17 on max resolution in 4D while simultaneously, in the background, figuring out the cure for cancer and solving the 3n+1 conjecture?
thank you AWOL and Shapaget , i am not willing to go that low AWOL , i am allowed to use any chip as long as i design the circuit to handle it , any ARM chip for example can be used , ( i can use modern chips)
the thing is , i cannot use an operating system like linux no , i must write everything from scratch even the video generating part (if a GPU is not used) i also can use a GPU chip , it's just that i must do all the circuit and programming .
Shapaget , being able to have a decent display in HDMI , and me being able to properly control it and interface with external devices like keyboards and stuff , and i must be able to communicate with an SD card , that's all i need ( i know most of the protocols and can do the programming , the circuit and how to install everything all together is the current problem but it can all be solved with time)
amine2:
thank you AWOL and Shapaget , i am not willing to go that low AWOL , i am allowed to use any chip as long as i design the circuit to handle it , any ARM chip for example can be used , ( i can use modern chips)
the thing is , i cannot use an operating system like linux no , i must write everything from scratch even the video generating part (if a GPU is not used) i also can use a GPU chip , it's just that i must do all the circuit and programming .Shapaget , being able to have a decent display in HDMI , and me being able to properly control it and interface with external devices like keyboards and stuff , and i must be able to communicate with an SD card , that's all i need ( i know most of the protocols and can do the programming , the circuit and how to install everything all together is the current problem but it can all be solved with time)
Do you consider the Arduino, a "working" computer?
Because you certainly could build that.
Though I would suggest an MSI ALU, like the 74181, rather than building your own! A look at the equivalent gate diagram for that chip would be instructive of what you are up against.
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What do you consider a "computer" to be ?
what's the temperature - Google Search -
Are you going to program from scratch (assembly language), or an interpreter / compiler programming language ?
How about an 8008 processor, using assembly code?
hey , thank you guys again .
well i am not meaning the general definition , the major challenge would probably be the programming , i can use a processor such as the one in the RPI for example but i need do design my own circuit for it .
it needs to run at a frequency higher or equal to 250Mhz .
i am used to C and assembly programming . you can build the bases of the program in assembly then write an interpreter and get going , so i dont think that would be problematic , if i manage to get my code to run and to control the pins ports and stuff , then my problem would then be solved , i must program everything from scratch , even the video protocols .. etc
amine2:
hey , thank you guys again .
well i am not meaning the general definition , the major challenge would probably be the programming , i can use a processor such as the one in the RPI for example but i need do design my own circuit for it .
it needs to run at a frequency higher or equal to 250Mhz .i am used to C and assembly programming . you can build the bases of the program in assembly then write an interpreter and get going , so i dont think that would be problematic , if i manage to get my code to run and to control the pins ports and stuff , then my problem would then be solved , i must program everything from scratch , even the video protocols .. etc
amine2:
hey , thank you guys again .
well i am not meaning the general definition , the major challenge would probably be the programming , i can use a processor such as the one in the RPI for example but i need do design my own circuit for it .
it needs to run at a frequency higher or equal to 250Mhz .i am used to C and assembly programming . you can build the bases of the program in assembly then write an interpreter and get going , so i dont think that would be problematic , if i manage to get my code to run and to control the pins ports and stuff , then my problem would then be solved , i must program everything from scratch , even the video protocols .. etc
At 250 MHZ, I would definitely use an SoC, System-On-A-Chip. But then are you actually "building a computer" or just applying powering to an SoC? How is this an Arduino Project?
This reminds me of the SAP-1 computer in a computer class I took eons ago. Later when I was teaching college, I assigned that to my students as a project to actually implement and build the SAP-1 computer.
you can google it.
nvm, just read op does not want to go down to ttl level.
hey , yeah thank you guys , i must design and build the whole PCB , and solder the chips . so i must start from just some chips and the parts (how small the chip is , or how complicated the soldering and placement process is does not bother ), so i guess yeah i am building it , also the programming must be from scratch .
thenk you doughboy , thank you mrsummitville
i can use a processor such as the one in the RPI for example
Yes but you are not allowed to buy them in penny numbers.
This has all the smatterings of an assignment.
Ben Heck's Apple 1 Replica (Youtube)
The above video shows an Apple 1 computer built on perfboard with hand wiring. No PCB required. There's surprisingly few chips required to do it.
AWOL:
It depends how you define "from scratch".
In the early 70s before cheap microprocessors, there were published designs for TTL home computers.
I don't think I'd like to go lower than TTL.
Today, you could fit dozens or hundreds of 6502-equivalent processors on a single FPGA.
A really, really sick part of me has a fantasy of building a computer from discrete transistors.
Basically - I have read about and looked into so much computer history - I have several books from that era and earlier which detail low-level logic circuits (one book I have shows things like flip-flops made with vacuum tubes - as well as how core memory works, plus all the math, etc). I've thought that maybe I could do something like cordwood design for the various modules, or maybe individual "cards" like the IBM 1401 (SMS cards) - standardize everything, solder them up, plug 'em together, etc.
Then the sane part of me returns, and realizes that to attempt something like that would be absolutely insane; I have better and more numerous things to do with my time.
Then there's the part that wants to build a low-level TTL IC based CPU - like the one used for the Buster robot in David L. Heiserman's book "Build Your Own Working Robot"...
I need help, apparently... 
Grumpy_Mike:
This has all the smatterings of an assignment.
I rather thought that was made clear in reply #3.
cr0sh:
A really, really sick part of me has a fantasy of building a computer from discrete transistors.
There's stuff on the Web about a guy who built a processor out of relays in his home, IIRC.
Having worked in Strowger exchanges, I can only imagine the racket it makes!
A computer was once designed from absolutely nothing. If it happened once, it can happen again.
OK , thak you guys , one more thing . the raspberry PI uses a processor that does the processing and the graphical job all together , that's what i am going to do , now can you guys recommend a good chip that i can use ? microcontroller or processor .
decent RAM and clockable at more than 250Mhz . thank you
the raspberry PI uses a processor that does the processing and the graphical job all together
No, the processor and the GPU are distinct functional blocks, they just happen to share the same slab of silicon.
I'm fairly sure that the RPi foundation isn't selling bare SoCs, and even if they did, soldering BGAs is not for the inexperienced.
i am not the one that's going to do the soldering . i am just gunna do the circuit design and programming later , all i need is a processor or a chip that i can freely program ... mmeeeh damn this will require some deep and long research to find the needed reference