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 Age. 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'. 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". 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