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Don
March 12th, 2006, 11:00 AM
About 10 years ago I designed a couple of single board computers. One was based on the Motorola 68HC11 and the other was an 80C32 board. Both had 32K of EPROM and 32K of RAM. Both came with a BASIC interpreter in ROM. They also had an identical set of I/O devices (printer port, 24-bit parallel port, 8 or 12 bit D/A, 8-channel 3 mode A/D, battery backed RAM and real time clock). All this on a 4 by 6 inch board. I tried selling these without much success under the name of D. C. Micros.

A couple of years ago I decided to bring the HC11 back to life and designed an expansion board that was also 4 by 6 inches in size. The expansion board had 2 serial ports, another 32K of RAM, floppy disk interface that supports 4 drives (360K or 720K) and an IDE hard drive interface. The IDE interface supports up 128 partitions of 16 megabytes each. It runs the FLEX 2 operating system (6800 version) without modification.

Not sure what all this information is worth but thought I would share it with you all.

Don

MoonShadow
March 13th, 2006, 02:21 AM
That sounds quite interesting. Maybe you could help me with the design and construction of a homebrew?
I'm interested in homebrews because you can do pretty much anything you want with them, like BASIC interpreters, writing monitors (or sub OSen, if you like), designing games (in 6502 assembler... lol.), etc.

For a start, I need to decide on what processor to use: 6502 or start simple with a 4004? Or use 8080/8086 or go a completely different direction and use RISC or sum'n.
After that, I need to find a place to get EEPROMs and processors work out if I can pull ram chips off some old ram stick or dead mobo or whatev.

Then I need to design it. I'd like to fit it somehow on to a dead ISA/PCI card or this crazy big white wierd board I have lying around...

Then comes the writing of the software et microcode et stuff.

I think that's all. Bye for now.

MoonShadow

P.S. I'll try to get some pics of the big white one. It looks a little like a really tall S-100, but I'm not sure. It says "tty interface" on it. That's all.

Don
March 14th, 2006, 10:41 AM
You've got a lot to chose from. :-) Any of the 8-bit processors is a good place to start. Then when your feet are wet you can jump into the big stuff. :-) Places like Jameco, JDR, DIGI-KEY & B.G.Micro are good sources of parts. Do a little shopping because some of their inventories overlap so one place might have a better deal than others.

Development tools is always an issue and as a hobbiest I don't like to spend a lot of money on that. Do a little internet shopping and you can usually find some pretty good freeware and shareware that will do the job. Some of this stuff is quite good and some is just plain junk. You'll have to make the determination which is which. Good luck with your projects.

Don

ziloo
March 15th, 2006, 07:04 AM
Greetings Don!

It is great to have an/another hardware designer among the Vcf gang.
I vaguely remember the name DC Micros but I can't remember where and
when. With the popularity of data acquisition and control systems
using stand-alone boards, I am surprised that your product did not fly.

There is a wealth of real computer enthusiasts on this forum, and I am
looking forward to see more colaborative effort among them to bring some
vintage designs/ideas back to present time again.

ziloo

Don
March 15th, 2006, 08:39 AM
Came as a big shock to me too. :-) I had an add that ran in TCJ (The Computer Journel), Microcomputer Journal (Computer Craft) and Circuit Cellar Inc. magazines. What killed me was the cost of advertising. :-( Circuit Cellar charged $1000.00 a month. TCJ magazine was $200 for a year, I think. I can't remember what Microcomputer Journal charged but is wasn't cheap either. As you know, if you don't advertise you don't sell so there I was.

I only sold a total of 8 of the 80C32 boards, 4 assembled and 4 kits. In the whole time I only had one tech support call. He could have answered his own question if he had read the first 4 pages of the manual. But, I had fun. It was something I wanted to do so I did it and now it's out of my system. I still have a few of the blank PCB's sitting in a box around here someplace. Can't bring myself to pitch them in the garbage.

Don