semi-homemade micro - test-drb@ccmp.vtda.org

13 Nov 2005

...

Subject: Re: semi-homemade micro
   From: woodelf <bfranchuk at jetnet.ab.ca>
   Date: Sun, 13 Nov 2005 16:18:41 -0700
     To: General Discussion: On-Topic and Off-Topic Posts <cctalk at
classiccmp.org>

Allison wrote:

 Uhm, what about 12bit[OS8 srt-8]?   There are few
othter word lenths
than those that are not unobtainium.

Well what about them? 
What do you mean by "Well what about them?"?

...
   You can only get the 16 machines easly and resonable
source of a OS.  
     Explain that from your perspective. 
 My perspective is things that I have seen in my past other than DEC or 
IBM or other BIG IRON.
That  was mostly 8080's , Z80's and other items advertised in BYTE. CP/M 
was the only one
that I know of  that you could get source for to adapt to your 
computer.  Once the PC arrived
open source vanished.  Sure  linux  is open source but who can read  or 
adpt the several meg
of source to a small machine.  Minux was a nice try but it lacked a C 
Compiler. Small C went
a DEAD end route as you could only use it if you bought the out of print 
books. 
Really! theres more stuff about smallC than ever on line.  Maybe back 
then life was hard but now with the 'net and Google I'm getting to try
and use those things that back then were either too exotic or hard to 
find and maybe even too expensive [especially hardware].  Even Minix 
has evolved (V3.x now).

...
   The 68000 yes still works best with 64k addressing.
Oddly the only micocomputer chip I like ( other than the 6800/6809) is  
National Semiconductor's 16032 is another chip that you could never get.

T-11 regular instruction set of the PDP-11.  Not too hard to find.
Z8001 and Z8002s I have a few of.  Z280, theres an interesting varient 
of Z80 with 24bit MMU that looks like the DEC PDP11 MMU (even I&D!).
 Yes I know I keep forgeting the 11 but I got forced into using PC's so 
only now do I have the time and a tiny amount a money for classic computers. 
My last employer went downhill as did my job with it so I have time and 
very little expendable cash.  However with junk, spares and imagination 
I achieve a lot with near nothing.  PCs I find costly and less productive.
Maybe I'm more of the do it and don't tell me how it's hard person.  I'd 
be dangerous if I had gobs of cash and free time converge.

...
 From scrap and salvage I'm building a lot of stuff
around here from 6M VHF SSB radios to really oddball 1802 systems.  

Want to try an emulation project?  take a 8048 or 49, strap EA 
(uses external rom then) and write a program to make port 0 and 
some latches and stuff on the bus port look like a version of
your favorite CPU of any word length.  Sure it will be slow 
(8049 @11mhz run instructions at 1.3us) but different! hang 
ram rom and IO even front pannel on the emulation and you have
anything you can imagine and fit in 4k or eprom and 128bytes 
of internal ram (8049). Those 8048s and 49s are common and 
easily found in keyboards (LK201 has the faster better 8051!)
and is a cool old cpu to work with.

Allison