bit slice chips (was Re: Harris H800 Computer)

Jon Elson elson at
Sat Apr 23 10:33:59 CDT 2016

On 04/22/2016 11:10 PM, Jon Elson wrote:

Yikes, too many typos, let me try over!
> I built a 32-bit micro-engine for a project that was 
> eventually going to be an IBM 360-like CPU.
> I picked the 360, not because it was the greatest design, 
> but it was VERY well laid-out and would be easy to write 
> efficient microcode for.  I used the 2903 with 2910 
> controller.  I was able to get it to run at 8 MHz, with 
> 3-address operations running at 6 MHz.
> But, the project got bogged down, at a certain point, I 
> realized HOW MUCH more work lay ahead of me to get a 
> working system.  I had to add 2 more features to the 
> micro-engine - a 256-way branch from the op-code, and some 
> OR gates to OR in the register address fields.  Then, I 
> had to build a system bus and memory interface.
> (I was going to make the I/O architecture much more like a 
> PDP-11 than the 360 channel architecture.)  Then, I had to 
> design a general-purpose peripheral controller.  I had a 
> VERY rough sketch for about a 20-chip micro-machine using 
> (probably) 3X byte-wide EPROMS for instructions) that 
> would hopefully run at 4 MHz.  Then, I had to build a SCSI 
> controller (I already had a SASI disk on my S-100 system), 
> a serial mux and a tape controller.
> Finally, I had to write at least a primitive OS and figure 
> out how to come up with compilers for it.  Had I known 
> that UNIX-360 existed, I might have tried to make some 
> kind of port of that. But, obviously, YEARS of work would 
> have been needed to make it usable.
> See for some 
> pics and description of it.
> Jon

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