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MotherBoard Schematics

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82c206 chips pdf

Does any know there is any mother board schematics for 486,585 or Pentium CPU'S.

Or any other info on building your own mother board from scratch???
 

robotman

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motherboard isa 80486 service manual

hexFet,

I use to design PCs for a living several years ago. PII was the last family I designed for. A lot of things have changed since I used to do it.

As for designing one from scratch, that depends on a lot of things. What is your level of expertise? Many of the designs are now requiring high speed design (busses are at least 133MHz or better). If you feel comfortable with high speed design, then go for it as long as you have the ability to make high density boards and mount BGAS (all core logic chipsets are BGAs these days).

If you want to do a 486 design, that it pretty easy as long as you can still find chips.

As for designs, here is a link to an in*tel design. They have many others, just search..

f*p://do*nload.int*l.com/design/chipsets/designex/S290657.pdf

Good luck and it you need anything else, let me know. I still have some friends that still do it. I can talk to them.

robotman
 

jhallows

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Here is some links to get you started:

Datasheets:
hxxp://developer.intel.com/design/intarch/intel486/docs_486.htm#Datasheets

Complete 486 Schematics:
hxxp://developer.intel.com/design/intarch/schems/ulpsch.htm

Designing Hints, (One my Gems of links)
hxxp://www.cate.fiu.edu/CourseMaterials/micros_lab/index.html


You are quite vague in what you want to do. PM if you need help.

Remember replace x=t in links.



<font size=-1>[ This Message was edited by: jhallows on 2002-03-18 06:17 ]</font>
 

jhallows

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Robotman now that I know you use to design motherboards I know you can help
me.

I am basically designing a 486 embedded system for mainly educational
purpose, (never design a PC motherboard and want to try it). I have choosen
to use the 82c206 multifuction chip for interrupts, timer, dma, and rtc. My
problem is that it runs at 8mhz (roughly max freq. of the AT bus which I am
not implementing). The chip I am using is a Intel 80486 but not at a fixed
frequency. My problem is the wait states. The 82c206 can only generate a maximum of 4
wait states at 8mhz each cycle but my cpu may run at 100mhz, (DX4 for
example). What is a possible solution to my problem? Remember I may have a
CPU at 25mhz, 33mhz, 66mhz etc....

I do not want to use any North Bridge and South bridge based chipsets.


<font size=-1>[ This Message was edited by: jhallows on 2002-03-23 18:43 ]</font>
 

robotman

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jhallows,

First, what you are missing is the core logic bridge. In a system, there are two types of chips that connect the processor to the standard PC peripheral set. They used to be referred to as the core logic chips and the I/O peripheral chips. Todays terminology is the North and South Bridges (and use PCI for connection between north and south bridges).

The core logic converts the processor bus to a set of high speed peripherals that the processor needs to run. Typically this is the SDRAM controller (for 486, it probably will be EDO or FP DRAM) and an ISA bus. The ISA bus is then connected to the 82c206. If you are not familiar with the ISA bus, then see the PC104 page.

Since I saw that you did not want to really use any external chips (north bridge or core logic) then your only option is to roll your own core logic. This is considered to be medium to very complex depending upon the amount of functionallity that you want to add. Remember, you need RAM, boot ROM, and some sort of ISA bridge as a minimum. Many vendors choose to implement more. If you really want to roll your own, I will try to pull out some of my old stuff to help you out.

If you do want to use a core logic chip, let me know. I will try to find a vendor or two that still makes them (this will be tough). Candidates were (and still might be) ALI (acer labs), Chips and Tech (now intel), OPTI (not sure if they are still in business), and maybe SMOS (seem to remember they were thinking about it. Another vendor that I did a design with was PicoPower. They were acquired by Cirrus logic and then they sold off to national semi. I don't think they sell the product anymore, but it was the PINE chipset. This and the 82C206 pretty much took care of a lot of stuff.

Just a suggestion or two, If you are trying to learn about 486 design, the you are heading down the right path. If you are trying to get a 486 system built, check out the Intel 486GX hummingbird chip or the AMD SC400 and SC500 elan families. They provide a lot of what you want already packaged up.

robotman
 

jhallows

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On 2002-03-19 03:57, robotman wrote:

Since I saw that you did not want to really use any external chips (north bridge or core logic) then your only option is to roll your own core logic. This is considered to be medium to very complex depending upon the amount of functionallity that you want to add. Remember, you need RAM, boot ROM, and some sort of ISA bridge as a minimum. Many vendors choose to implement more. If you really want to roll your own, I will try to pull out some of my old stuff to help you out.
This more along the lines I want to do. The main problem is I can't get chipsets easily and it takes the fun out of learning.

I don't know how to handle the BE1-BE4 lines for 8-bit access and wait-states generation.
I know on the 486 you can select 8-bit bus size but how about the speed problem? Do I just hold the READY line for 8mhz from the output of the 82c206? And DRAM would be nice, but I am considering using 128kb x 4 (512kb) sram for now. Enough to get R*M D*S 6.22 running.

If you do want to use a core logic chip, let me know. I will try to find a vendor or two that still makes them (this will be tough). Candidates were (and still might be) ALI (acer labs), Chips and Tech (now intel), OPTI (not sure if they are still in business), and maybe SMOS (seem to remember they were thinking about it. Another vendor that I did a design with was PicoPower. They were acquired by Cirrus logic and then they sold off to national semi. I don't think they sell the product anymore, but it was the PINE chipset. This and the 82C206 pretty much took care of a lot of stuff.
I think the 82c206 and my own chipset will do fine. I ain't designning a full blown PC. Just enough to get by.

Just a suggestion or two, If you are trying to learn about 486 design, the you are heading down the right path. If you are trying to get a 486 system built, check out the Intel 486GX hummingbird chip or the AMD SC400 and SC500 elan families. They provide a lot of what you want already packaged up.
I am using old 486DX chips, (easy to get).

--
John Hallows
 

BENOIT

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if interested I have the service Manual
of a SAMSUNG 386 Motherboard (80386-33MHZ)
Model SD840 SERIES
with full diagrams (made with OrCad)
and explanations.
the manual makes 300 pages , So if you
are interested I could lend it to you
so you do the copys interesting you and
then send back by postal Mail.
MB.
 

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