Building a new ZX Spectrum from all new parts

That’s pretty neat, the ULA is just a gate array after all.

[Edit] I forgot to mention I have speccy and ZX81 ULAs from Charlie and they are top notch and have been working flawlessly, and especially in the case of the ZX81, better than the original.

Chris Smiths’ book, “The ZX Spectrum ULA: How to design a microcomputer”, is an excellent read if you like to imagine yourself as a hardware guy back in the 80’s.

http://www.zxdesign.info/book/

There's also the superfo harlequin that disintegrates the ULA into 74 series logic:

https://www.bytedelight.com/?product_cat=harlequin128

I'm currently building the 48k version

For anyone else who's unfamiliar, that's a "Complex programmable logic device"

https://en.wikipedia.org/wiki/Complex_programmable_logic_dev...

> A complex programmable logic device (CPLD) is a programmable logic device with complexity between that of PALs and FPGAs, and architectural features of both. The main building block of the CPLD is a macrocell, which contains logic implementing disjunctive normal form expressions and more specialized logic operations.

Making a second, third, or fourth set of manuals would have obtained substantial economies of scale whether in the 20th or 21st centuries.

There was a time where PDF didn’t exist, there were no tools to create, let alone view or print manuals. Even when these became widespread, a number of troglodytes would get bent out of shape if their new appliance didn’t come with a (preferably bound!) paper manual. Most of these folks have either passed on or begrudgingly assimilated.

For small-run offset printing (as opposed to laser-printer-quality stuff you get from print-on-demand shops, including PoD reissues of old titles the big academic publishers sell under the guise of new copies), the books themselves are basically free compared to the plates. A bookshop owner who also worked in printing once told me it was in the order of $1M for the plates for a 300-page book, and then negligible costs for the actual books until you get past at least tens of thousands of copies. So printing one manual or a hundred of them is a very different proposition from a normal-sized run of like 50k of them.

Just publishing on the web wasn't an option at the time. But damn! I remember reading at the back of a C64 manual as a kid. Trying out the various "commands". I had no concept of "programming" or "basic". This was just how the machine worked and I was occasionally in the mood of figuring it out. That time will never come again, for me or anyone else.

The cost for the manuals seems high--at least if you're willing to have some flexibility on paper choice. I'd think that one volume print on demand from Amazon would be more like $10 although it's admittedly been a while since I looked at pricing.

The Spectrum manual was good, with the usual programming guide and a breakdown of the memory map and system variables, but the Jupiter Ace manual also included example circuits so you could build your own peripherals...

For those wanting a link: https://www.bankofengland.co.uk/monetary-policy/inflation/in...

I did Ben Eater's 6502 kit and expanded on it a lot. You're right, it really gets you to appreciate how computers really work, in a much simplified way of course, compared even to for example the first IBM computer.

Implementing something like a FAT file system for example also really makes you appreciate the deeper concepts of how an OS works. I only did a very simple FAT implementation, without subdirectories, but even with that, terms like FAT and sector became very concrete things instead of vague concepts.

Replacements do exist both for the membrane as well as the rubber keys on top. The author lists it in the parts page under "Misc": https://www.lostretrotapes.com/zx-spectrum-issue-3b-parts-li...