#z80

Conoce la Xerox 820 (presentada el 9 de junio de 1981)

Antes de que IBM cambiara las reglas del juego, Xerox intentó conquistar las oficinas con una fórmula clásica y ultra confiable.

Olvídate de interfaces gráficas costosas; la Xerox 820 (código clave "Worm") fue diseñada para ir directo al grano con el estándar de oro de la época:

Procesador: El mítico Zilog Z80 de 8 bits.

Sistema Operativo: CP/M (el rey antes de MS-DOS).

Lenguaje: Microsoft BASIC integrado para programar.

Aunque no revolucionó el mercado, es una joya histórica de cuando los gigantes de las fotocopiadoras querían una tajada del futuro de la computación personal.

¿Llegaste a usar el sistema operativo CP/M o a programar en el eterno Z80?

Amstrad CPC464 (1984)

The Amstrad CPC464 arrived in 1984, two years after the launch of the ZX Spectrum, and quickly became one of the standout home computers of the decade in Europe.

Its success came from the fact that it offered not just a computer, but a complete and user friendly system.

With its built in cassette deck and, in many cases, its own dedicated monitor, it looked more modern and more neatly packaged than many of its rivals.

Its development was not entirely smooth, as the early plans changed several times before the final design was completed.

Once it reached the market, however, the CPC464 quickly proved that Amstrad understood exactly what home users of the era wanted.

It was stylish, practical, and had a surprisingly serious presence in the living room.

Under the case was a Z80A processor running at 4 MHz, paired with 64 KB of memory.

Sound came from a three channel AY chip, which helped create the distinctive audio world of the era’s games and demos.

The CPC464 also offered multiple graphics modes, allowing developers to balance detail and color depending on the needs of the software.

One of its real strengths was the built in Locomotive BASIC, which was widely praised for its speed and ease of use.

It is no surprise that the CPC464 remains a true retro legend, a machine that still brings back memories of games, cassette loading, and the unmistakable magic of 1980s home computing.

Osborne Vixen (1984)

The Osborne Vixen was a portable (technically, luggable) computer introduced in late 1984 by Osborne Computer Corporation, the company famous for the groundbreaking Osborne 1 (1981).

It was designed to be a compact business machine running CP/M, but by the time it reached the market, IBM PC compatibility had already become the new standard — effectively making the Vixen obsolete on arrival.

The Vixen has a 4 MHz Zilog Z80 (like the Tandy TRS-80, ZX Spectrum, etc.) with 64 KB RAM and 4 KB EPROM. It has a 7-inch diagonal amber display that can show 24 lines by 80 columns of memory mapped video. It uses two 400 KB disk drives, utilizing double-density double-sided 5.25" diskettes. As a luggable, it weighs about 18 pounds (8.2 kg). Contemporary advertising pointed out that it could fit under the seat in an airplane, with dimensions of 125⁄8 by 161⁄4 by 61⁄4 inches (321 by 413 by 159 mm).

The appearance of the ZX Spectrum+ 128 is similar to the ZX Spectrum+, with the exception of a large external heatsink for the internal 7805 voltage regulator added to the right hand end of the case, replacing the internal heatsink in previous versions. This external heatsink led to the system's nickname, "The Toast Rack".

New features included 128 KB RAM with RAM disc commands, three-channel audio via the AY-3-8912 chip, MIDI compatibility, an RS-232 serial port, an RGB monitor port, 32 KB of ROM including an improved BASIC editor, and an external num keypad.

The Zilog Z80 processor used in the Spectrum has a 16-bit address bus, which means only 64 KB of memory can be directly addressed. To facilitate the extra 80 KB of RAM the designers used bank switching so the new memory would be available as eight pages of 16 KB at the top of the address space. The same technique was used to page between the new 16 KB editor ROM and the original 16 KB BASIC ROM at the bottom of the address space.

The new sound chip and MIDI out abilities were exposed to the BASIC programming language with the command PLAY and a new command SPECTRUM was added to switch the machine into 48K mode, keeping the current BASIC program intact (although there is no command to switch back to 128K mode). To enable BASIC programmers to access the additional memory, a RAM disk was created where files could be stored in the additional 80 KB of RAM. The new commands took the place of two existing user-defined-character spaces causing compatibility problems with certain BASIC programs. Unlike its predecessors, it has no internal speaker, and can only produce sound from a television speaker.

Long Live the Z80! - David Henderson  

i’m trying to write a simple program to read files from a tar archive loaded into memory (given the starting address of the tarball and a filename, find the file’s size and a pointer to its contents) on the ti-84+, and i’m having a lot of fun!

i’m about 300 lines in and all i have left to do is write a wrapper ui and figure out file i/o with the ti-84’s cursed filesystem, and i should be good to go!

things are going pretty smoothly, mostly because i already have a reference implementation of all the algorithms i need written in c and tested on my amd64 computer. most of what i’m doing now is just translating c code into z80 assembly, which isn’t incredibly difficult, because c just generally translates well into assembly code.

it feels very different from c. it’s definitely harder, but i can appreciate the close connection to the hardware you get from working with assembly. it’s super cool to be able to see the machine code translation, line-by-line with the code you wrote.

I must admit I haven't used Z80, or any 8 bit assembly languages, so can't speak from first hand experience. But I just read up on it a bit, and it seems cool. I like that it's compatible with the older 8080, when possible I think backwards compatibility is something that should be strived for. And it seems they added a bunch more instructions, and simplified some things, which is obviously a nice thing for the programmer.