I worked at Mostek maintaining the Fairchild Sentry testers used to test the Z80s when they first began to manufacturer them. The second computer I every
built (parts, pcb, solder) was the SDB-80 which was the Mostek Software Development Board for the Z80 with 16K bytes (8 - MK4116 16K bit) dynamic RAMs
which Mostek also made. The first wire wrap board I ever made was a 48K byte dynamic RAM board also using MK4116s that worked with the SDB-80. I can
tell you there were a bunch of happy technicians when we were told that Mostek would be second sourcing the Z-80 and even happier when we were told we
could buy SDB-80 kits and build them ourselves! Those were really fun days. I still have a Zilog Z80 in a ceramic package that says it was manufactured in
Dallas even though Mostek was actually in Carrollton a suburb in Dallas County just north of north-west Dallas.
At around that time, a lot of the handheld devices were getting powerful, so the ultimate decision to use that instead of any other device may have been simply because it was what someone was experienced in.
From the very little production/shop floor experience I have, it was interesting (at the places I worked) to see that the tools used in production were different to what the rest of the organisation were using. In other words, different CAD tools, different procedures, and different hardware. I'm not saying it is ropey, but a lot of stuff is designed to be one-off or very low quantity production.
Regarding the suggestion of Z80 origins made to look like a non-Z80 device, I've no idea. Certainly it won't execute Z80 software without modification and assembly with a different assembler.
Many processors at the time were similar, from a birds-eye view. Even the different processor designs that soon emerged like RISC and SPARC still have instruction sets and registers, and buses.
There was historically plenty of anti-Japanese tech sentiment in the 1980's, when many people thought that Japanese firms were copying or stealing ideas. That idea still exists today. It's unfounded, and likely no more than western firms stealing western ideas from each other. Perhaps that sentiment inspired the suggestion that it looks similar to the Z80 I cannot tell, since I don't know where and when that suggestion originated. The Japanese government encouraged firms to buy rights to patented tech, that was a major policy at the time.
Depending how keen you are to research down that road, there are some books worth reading, they mention names of people who would know better than speculation, of which unfortunately there is a lot of on the Internet. The first is We Were Burning, and the second is Industrial Innovation in Japan. The first is an easier book to read. According to that, Sharp was extremely quick off the block developing calculators, and amongst the first to productize (not invent) CMOS, so it's quite natural they would either license a Z80 design, or design their own chip. Neither of which would be good reasons to fake instruction names to look like a different processor.
Very interesting musings about Z80 and possible 'mimicry' ... And thank you for the literature suggestions.
I believe having gotten some idea of Sharp policy in the dozen or so years I've made a living out of their products in many applications.
Do share your viewpoint that a lot of Japanese manufacturers of the time had more than enough innovation capability of their own, in order
not having to rely on copying; they did however clever- and selectively enter into strategic alliances and joint ventures.
I was appalled to learn that the company was recently taken over by Foxconn, of all the lousy manufacturers of today ...
The Japanese goverment should be ashamed for not having done anything to prevent this - the company that produced the unique amber
EL-displays for the Space Shuttle and where Philips had to buy all their LCD patents !
Back to the good ol' eighties and Sharp policy: I still feel the only explanation that makes sense for the model number, (LH-)5801, is as follows.
Next to their OEM production of Z80 clones - LH080, etc. - they wanted a proprietary microprocessor design for their indeed innovative line of
pocket computers. However they did not want to isolate these products too much from the brands and models that had become well-known
market leaders, in order to reach the broadest possible acceptance. So they devised the number 5800, with a wink to the 6800; but in order
to prevent the impression that they would suggest to make a predecessor, or down-graded version, they made the number their own by changing
it into 5801. Speculative ? Sure, but have I "entered into the realms of phantasy" ?
There was btw a LH-5803, which was meant to emulate the 1500 in its successor, the PC-1600 in order to attain full SW-compatibility. (It didn't
work 100% - much like my XP Pro overlay on Windows 10; this was probably also the reason for the PC-1600 being a less stable system than the trustworthy 1500).
It could be derived from the Z80, I really cannot tell one way or another.
I used the Z80 a lot in the home 8-bit computer era with plenty of machine code (I had no assembler) but I cannot recall much apart from a few instructions and op-codes that won't seem to leave the brain : )
The embedded 8-bit stuff I encountered later was mostly Motorola based (6805 and 6811 particularly) and a few other manufacturers.
You can create your own blog on any topic just by clicking on the "Create" button at the top of the page.
Threads like this Z80 topic just fade from view unless members keep adding anecdotes, so I think it is great to add stories directly to the thread, even if they are only peripherally related.
You can create your own blog on any topic just by clicking on the "Create" button at the top of the page.
Threads like this Z80 topic just fade from view unless members keep adding anecdotes, so I think it is great to add stories directly to the thread, even if they are only peripherally related.
As for degrading eyesight I'm reliant upon my bench binocular microscope just to solder 1960's tech like DIP ICs and through hole.
My spare parts are so old that I have to remove the unwanted oxide layer from them (just like my brain).
I don't like too much SPICE in my food.
Analog turntables - Don't get me started! The analog signal is distorted prior to recording so it can be reverse distorted for playback to support the RIAA equalisation.
And also seem to also ignore other distortion influences such as wow and flutter, stylus/cartridge momentum and contact friction variations
Like oscilloscopes, sound should be sampled at about 5x or more than the desired maximum bandwidth.
And how does one get a speaker to playback perfect square waves?
