On Wednesday, December 25, 2019, 09:44:21 AM PST, jim bell
   <jdb10987@yahoo.com> wrote:

>The New York Times: Chuck Peddle Dies at 82; His $25 Chip Helped Start the PC A
ge.
[1]https://www.nytimes.com/2019/12/24/technology/chuck-peddle-dead.html

   >6502 microprocessor.
   I was a fan of the Z80 microprocessor, which I viewed as 'the 8080 done
   right'.  [2]https://en.wikipedia.org/wiki/Zilog_Z80
      Single +5 supply, single-phase clock, TTL compatible I/O (except for
   the CLK, which was pulled to +5 with a resistor), and a decoded memory
   and I/O system.  I also thought the relatively large number of internal
   registers, much more than 6800 or 6502, was more efficient, minimizing
   memory accesses.   The Z80 also had a mirrored set of registers, and an
   enhanced instruction set, including relative-addressing.
    It also generated a 7-bit refresh address, making use of DRAM easy.
   This, however led to a problem when some DRAM manufacturers of 64K
   DRAMs (I think, including Micron Technology) built DRAM chips needing
   an 8-bit refresh address.  It meant that those DRAMs simply would not
   work (reliably) if they depended on Z-80 refreshing.   If Zilog had
   only added another counter to that chip in the beginning!
   Starting in the summer of 1978, I built my homebrew "Bellyache I", the
   name parodied from the "Illiac IV".
   [3]https://en.wikipedia.org/wiki/ILLIAC_IV
    I used what would look like S-100 bus hardware, but I was so disgusted
   by the (lack of) 'architecture' in the S-100 that I merely used a
   motherboard and prototype boards, and I completely re-defined the bus.
   This meant that I only could add functions I myself had designed and
   constructed.  The Bellyache I eventually had as many as 600 IC's, and
   this included my prototype "SemiDisk", a S-100 prototype card with 32
   memory sockets, each with 8, 2118 (16K, 5-volt only) DRAMs in CERDIP
   packages, stacked 8 chips high.  This was completed in about October
   1980.  (I started work at Intel early July 1980)  It looked like a
   brick, and weighed just about as half of one!   In implementing that, I
   had just invented the Disk Emulator, or semiconductor disk.
   Technically, there may have been a similar thing for mainframes, but
   mine was the first for Personal Computers.
   My company, SemiDisk Systems, Inc, eventually built boards for the
   S-100 bus, Radio Shack Model 2, IBM PC (8-bit bus), IBM AT (16-bit
   bus), and the Epson QX-10.
            Jim Bell

References

   1. https://www.nytimes.com/2019/12/24/technology/chuck-peddle-dead.html
   2. https://en.wikipedia.org/wiki/Zilog_Z80
   3. https://en.wikipedia.org/wiki/ILLIAC_IV