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Super-Slasher
December 15th, 2003, 04:19 PM
For quite a while I've been interested in expanding my knowledge of computer electronics by assembiling my own small homebrew project. I've recently come across an AMD 8088 processor out of some old cards that were on their way to the trash. I was pondering selling the chip for $5 or so, but then I started thinking why not let this be the brain for my future homebrew?

It's only an 8-bit processor, which will keep the simplcitiy down, but I have never thought about doing a project so complex. Can anyone recommend some good links of knowledge or plans for such a project, or even recommend a system for the newbee homebrewer? I'm open to any and all suggestions.

As for what I'd like my system to do, my plans is to have it on its own circut board (hand-wired if need be) and beable to do my own programming in it, wether it be through keyboard and monitor or through binary switches, like on the Altair.

Please fill me in... I'm kinda excited about a project such as this. To those who have homebrewed a system before, how difficult was it, how much did you learn from the experience, and how did your system work/what did you do on it?

tachyon
December 16th, 2003, 12:55 PM
The 8088 is a reasonable chip to start with, since in effect it's an 8086 code compatible version of the 8085; which is still one of the most popular training processors out there.

If you use a PC compatible computer, you will be able to use your PC to develop and test your monitor and later programs if you like.

A few suggestions if you go this way:

Make your serial port compatible in address, etc. with a standard PC serial port. That way you can 'emulate' your board on your PC, allowing you to test the monitor in RAM before you burn it to a ROM for your homebrew system.

Use static RAM. Large static ram chips are available that use the same form factor as eproms or eeproms.

Use eeprom to store your monitor. This will save you money over the long run.

Don't be too ambitious with your first attempt. You'll most likely either throw your project away in disgust or continue to bigger and better things. Either way, think of your first homebrew machine as a stepping stone, not an end of it's own.

Keep the clock speed slow. You can speed it up later, but the slower the clock, the fewer problems you'll have with interference and chips being too slow.

Regards,

-Tachyon

Super-Slasher
December 16th, 2003, 01:39 PM
Thank you very much for the advice. I'll try to take as much of it as I can during the process, if I ever start, that is.

As for the speed, I could care less how slow it is, wether it's 2MHz or 200 KHz, just as long as it functions.

:)

lither
January 6th, 2004, 11:32 PM
Can anyone recommend some good links of knowledge or plans for such a project, or even recommend a system for the newbee homebrewer? I'm open to any and all suggestions.

Have you started your project? I recently read a homepage talking about building a 8088 base single board computer that you might be interested.
http://et.nmsu.edu/~etti/fall98/electronics/zargari/zargari.html

CP/M User
January 6th, 2004, 11:39 PM
http://members.iinet.net.au/~daveb/p112/p112.html

Is this the kinda thing you're after?

Cheers,
CP/M User.

olddataman
January 12th, 2004, 12:37 AM
Years ago, in about 1976 or '75, Osborne & Associates published a book. If I remember rightly, the title was "Microprocessors in Logic Design." The book describes how one could use Micaroprocessors in the design oif the electronics of a Diablo Daisy Wheel Printer. It describes such things as "software implementation of the basic logic functions such as AND, OR.NOT and descrobed tje ise pf FIVE 8080 chips for drive and control.
I don't have any idea where to find a copy except libraries, collectors, and people of that ilk. It is a good introduction to the subject and was very popular You might be able to borrow one from soneone's collection
Ray

ravuya
January 17th, 2004, 08:58 AM
:lol:

I've got a Z80 and some Motorola controller chips around here. I should do that!

vbriel
January 25th, 2004, 05:25 AM
It's only an 8-bit processor, which will keep the simplcitiy down, but I have never thought about doing a project so complex. Can anyone recommend some good links of knowledge or plans for such a project, or even recommend a system for the newbee homebrewer? I'm open to any and all suggestions.

As for what I'd like my system to do, my plans is to have it on its own circut board (hand-wired if need be) and beable to do my own programming in it, wether it be through keyboard and monitor or through binary switches, like on the Altair.

Please fill me in... I'm kinda excited about a project such as this. To those who have homebrewed a system before, how difficult was it, how much did you learn from the experience, and how did your system work/what did you do on it?

This is how I started the replica 1 (apple 1 replica):

First I came up with a design layout. If you need examples I'm sure there are schematics out there with a google search. Next, start small. I built just the processor section and programmed an EEPROM to do a fast loop just to check the status of the address lines. From there I added my RAM and I/O controller and reprogrammed the EEPROM to send a specific code to the pins on the I/O. Once I had this part working I moved it to wirewrap as it was cheaper than prototype boards.

I suggest you use a serial port for your I/O as that is what most SBC creators use initially. It makes for a smaller circuit. I have some pics on my site documenting the process but not in full detail. It can be frustrating at times but if you remember not to try and build a full-blown system at the start you are better off.

http://www.applefritter.com/apple1/members/replica1/index.htm

Good luck!