84

It varied. There was no single method. Some people used assemblers on the target machine, others used cross-development tools. As an example of a large product for an 8-bit machine, I worked on the BitStik CAD software for Apple II and BBC Micro systems from 1984 to 1986. That used Apple II machines with Z80 CP/M cards for coding (with WordStar) and ...


56

There are many issues here. As it is already said in comments, decoupling capacitor is a must! 555 (non-CMOS) timer output is very much like the output of TTL ICs, however Z80 requires a firm logic one. When feeding Z80 clock pin from a TTL output, you should use pullup resistor of 200..500 Ohm. NMOS Z80 uses dynamic logic, that means it has some minimal ...


47

There are several aspects to consider to answer your question. The x86 architecture is backwards-compatible with the first CPU of the line, the 8086 (and its sibling, the 8088). What this means is that, when a modern Intel (or AMD) processor boots up, it starts in a mode which is compatible with the 8086 — if the motherboard's BIOS support is good enough, ...


46

People nowadays think of BASIC as something lesser and generally tied to puny microcomputers, but BASIC was the language of choice for many scientific, engineering and business computers in the 1970s. It had a strong foothold with mini computers, years before the microprocessors made its debut on the desktop. Think HP (Instrument) BASIC for all their ...


45

Gates and Allen used remote terminal access to a minicomputer (Harvard's DEC PDP-10) to cross-assemble, and simulate, their implementation of BASIC for the Altair 8800. Commodore Basic (for the 6502) is reportedly derived from Altair Basic, and also cross-assembled using Macro-10 on a DEC 10. Woz (and many other early Apple programmers) could code 6502 ...


44

As someone who did it.... We wrote an assembler for an 8080, as there was nothing affordable from Intel. We wrote it in ALGOL 60, if I recall, and ran it on a mainframe. the first thing we ran through it was .. itself, re-coded in assembler. Oh, and a boot-loader, though I think maybe we had already hand-assembled a minimal version of that into binary. ...


34

To understand what was going on with licensed and unlicensed ports of popular arcade games in the 1980s, you have to understand two critical factors. The video gaming culture of the time, and the preeminence of coin-op arcade games. The role of trademarks and legal trademark protections, which was the more crucial law pertaining to arcade game ports at the ...


32

This had a lot of drawbacks, like the limited screen size, the slow Disk I/O, the limited RAM needed for the tools and your own code, etc. Those are just drawbacks of having a slower or less capable computer. As that was the norm, I don't think anyone thought much of it. Even considering that, a lot of that may be alleviated by a simple setup involving a ...


30

The 8086 is source-code compatible with the 8080 (the other way around is not true). This means that most assembly code written for the 8080 can be assembled so that 8086 instructions are emitted. The only exceptions would be self-modifying code or code that relies on interrupts, which are handled differently on both processors. In fact, some assemblers, ...


28

The MK 3880 Mostek CPU Technical manual (it's the Z80 implementation from Mostek) has a section called "Hardware implementation examples" which may help you. Besides, the Thomas Scherrer Z80-Family Official Support Page has a section devoted to circuit schematics based upon the Z80 processor. If you are in Facebook, there is a group devoted to share ...


25

The same answer as everybody else, just with more detail: What I mean: An assembler is not an application exactly trivial to write. Oh, but it is. A "first" assembler on a platform simply reads some bytes, transforms them in a more or less 1:1 relationship to other bytes, that's it. The target architecture was very simple. There was no shared objects / ...


25

One prime example is the Econet networking system designed by Acorn Computers. Best known for their BBC Microcomputer and Archimedes systems, Acorn started with a range of modular rack-based expandable computers known as the System range, released from 1979 onwards. These machines were aimed at serious hobbyists, researchers, and industrial users, and could ...


24

Were there any 8-bit CPUs with 24-bit addressing? Not many. Most prominent and best fitting examples would be WDC 65816 of 1983 Hitachi 64180 of 1985 / Zilog Z180 of 1985 (only 19/20 bit) eZ80 of 1998 Then there 8/16/32 bit hybrids - able to run 8 bit code and available with external 8 bit data bus, but as well with 16/32 bit code (extensions): Zilog ...


23

The 1974 Altair 8800 kick-started the industry but at the time offered no keyboard, no screen, just a bunch of switches and lights connected directly to the bus and a counter to help you input or output sequential values. So you'd work out the binary representation of your program by hand and input it byte by byte, bit by bit. The world's introduction to ...


22

A few 16-bit processors can run 8-bit code: the NEC V20 series. The V20 and V30 are the ones you might encounter in a PC. The V20 is a pin-compatible substitute for the 8088, and the V30 for the 8086. These processors have a BRKEM instruction (in Intel's notation it would most likely be 'INTEM') which switches to the 8080 instruction set and jumps to an ...


21

So, nowadays, you'd have to be crazy not to use a PC and some nice cross-development tools when targeting these old machines. To start with, I still like to use my IIgs (or IIc-plus) when coding for the Apple II. Both are quite fast machines with more than enough memory to do the job. After all, editing source text doesn't get faster with a mouse and many ...


20

To volunteer a few: Acornsoft LISP. First released in 1982 on tape, disk and ROM chip for the BBC Micro and rereleased as a cartridge for the Acorn Electron in 1984; possibly related to the Apple II's Owl LISP. SpecLISP. Released in 1983 for the ZX Spectrum, a subset of Stanford LISP. It wasn't well-documented at the time, so is a little obscure. Includes ...


20

The 8085, which came out two years after the 8080, rapidly became more popular for most applications because it required only +5 V power (as opposed to +5/-5/+12 V) and less external support circuitry. (Today there are a number of 8085 single-board computer designs available, such as glitchworks and OMEN; 8080 designs exist but seem few and far between.) ...


19

The Sprint cassette player/recorder, specially designed for the ZX Spectrum, allowed 4X load and save speeds. It works by speeding up the tape four times the standard playing speed. It is meant to load programs originally recorded at the Spectrum ROM standard speed (1500 bps). It provides a shadow ROM that pages in when the CPU starts executing a SAVE or ...


17

It is worth remembering that by the time the home hobby microcomputers appeared, Computer Scientists had more that 25 years experience in building assemblers and designing bootstrap loaders. As a summer job in the mid-1960s, I worked as an operator in an IBM datacenter with a IBM 1401 - 16K of RAM, no disk, 5 tape drives a cardreader/punch and a printer. ...


16

There is no such thing as an 8-bit application for the x86 architecture, because the x86 architecture has always been at least 16-bit right from the first generation of x86 processors. The x86 does allow access to 8-bit registers, but the code is still 16-bit and the processor is still running as a 16-bit processor. Of course, if you're trying to run 8-bit ...


16

As far as the School market in Australia, the locally made Microbee was dominant in the 80's together with the Apple 2e and BBC. The Microbee was mainly sold in Australia (zero to USA) but also sold into Sweden and its neighbours, New Zealand and a few to Israel & Russia. As a result, the USA, UK, etc know very little to nothing about the Microbee. ...


16

In theory, it is fairly simple duplicating a tape. The problem with analog tape-to-tape copies is that sound quality lowers and spurious noises are also copied and more are generated into each new consecutive copy generation. It did not contribute to improve the situation, that later tape copy protection methods/turbo loaders (SpeedLock, Alcatraz...) were ...


16

If we're not talking about BASIC as a programming language, but the operational commands that surround it, then the answer is that they surely reimplemented the command structure of existing timesharing systems that offered BASIC, in particular the 1964 Dartmouth Time Sharing System (the progenitor of BASIC). There are nits to pick, however. The "command ...


16

This was more of a marketing question than a technical one. The historical fact is that most vendors of 8-bit personal computers chose to include BASIC. The simple answer as to why they made this choice is pretty obvious - It was the standard. So, slightly restating the question posed, one could ask "Why was BASIC the standard?" It was a standard in the ...


15

Were there any Intel 8080 based home computers? Yes, but the number is rather small, as at the point when the idea of a home computer as we know it today (and you describe) became popular, better 'versions' of the 8080 were already available, most notably the 8085 and Z80. Importantly for low cost computer design, they did away with -5 and +12V supply, thus ...


14

Preface: As with many early questions, it's up to the definition of network. It might be helpful not to tie this too close to our modern understanding of a connection between (mostly) equal peers. Well known networks on the micro/home computer side may be of course Acorns Econet introduced with the Atom in 1981 Sinclair's ZX-Net introduced with the ...


14

I'd just like to expand on a couple of points in lvd's excellent answer. Reset Circuit You might get by with just using a jumper wire to short the reset pin to ground for a brief moment after you've powered up the CPU. It's worked for me, but if you're having problems it's best to build a proper reset circuit. Many CPUs have a minimum length for the reset ...


13

Caveat: I can't confirm that this works acceptably, as I haven't been able to find any references to anyone who has done it, but by reading the datasheet of the 80C88 it seems it should work there, and it may also work on an original HMOS 8088, but that's less certain as the HMOS design wasn't static (although it could work at relatively slow clock speeds, e....


13

They used cross-development kits back then too. I worked briefly in a UK game developer in 1990 and all their Commodore 64 and ZX Spectrum games were developed on a PC with a proprietary kit. See for example Andrew Braybrook's diary covering the development of Morpheus on the C64, where they start to use Opus PCs and an Atari ST to develop on, connected to ...


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