Z-80 PC Emulator: ZX Spectrum Support and Virtual Peripherals

Emulators, Part II

The second part of the article will be devoted entirely to an emulator called “Z-80”.

It is undoubtedly the best of the existing emulators while also having modest hardware requirements. To run “Z-80”, you need at least 512 kB of RAM, any processor, and a graphics card compatible with the HERCULES, EGA, CGA, VGA, or PLATRONICS standard. If you want to emulate the 128K model, you also need 64K of EMS memory and any sound card to play that wonderful AY music.

The “Z-80” emulator lets you use almost all software created for every ZX Spectrum model, providing access to a virtual hardware environment (INTERFACE 1, MULTIFACE, MICRODRIVE). It makes it easy to use our software archive, which is most often stored on cassette tapes.

Included with the emulator is a schematic for an adapter connected to the CPT input, giving us equivalents of the EAR/MIC ports.

Programs can also be converted from 3.5-inch floppy disks saved in SAM COUPE format and from the Plus D system.

A major advantage of the program is its incredibly fast Z-80 mnemonic decoding algorithm. On a PC with a 486/50 MHz processor, the maximum emulation speed is 535.6% (so that’s five times the speed of the original Speccy—believe me, only then do some demos reach their proper pace, such as vector graphics demos).

Unfortunately, screen emulation is not as perfect: to see effects on the BORDER, we have to “freeze” the main screen. It’s a pity, because many programs use the border as an integral part of the screen.

When converting programs from tapes and floppy disks into a format compatible with the emulator, we can save successive headers and data blocks, creating a file with the .TAP extension on the hard disk. We treat it like an ordinary tape: we can rewind it, search for a particular file, etc., and then use the command LOAD "name" to load the part of the “tape” we’re interested in. This is especially useful when converting games with additional data blocks.

While the emulator is running, we can always:

• turn sound and interrupts on or off
• disconnect or connect INTERFACE 1
• change the emulation speed
• print the screen on a printer
• use any joystick:
  SINCLAIR 1/2, PROTEK, CURSOR, KEMPSTON
• save the contents of all memory, along with the register values, to disk
• save the screen image
• save any area of memory

Anyone who wants to use the huge databases and text collections available on IBM computers can convert them to “Speccy” format. (The author of this article managed to copy the book Alice in Wonderland and edit it from within the emulator.)

It is also possible to convert standard SCREENs (6912 bytes) to the most popular GIF format.

Unfortunately, “Z-80” is not free. Registration costs $20, payable to the author at:

         GERTON LUNTER
          PO BOX 2355
     NL-9704  CM GRONINGEN
        THE NETHERLANDS

An unregistered version of the program is available from our editorial office. We’ll record it for interested parties free of charge; just send us a floppy disk along with a stamp for registered mail, to the following address:

              WILL
        WALDEMAR DOROS
       ul. STALOWA 59/7
        53-438 WROCłAW

The complete package, which includes:

• the emulator
• a comprehensive manual in English
• a file with ROM memory patches (48/128 models)
• a schematic of the tape recorder interface
• a program for converting files from other emulators

...takes up 318 kB.

We also have 80 MB of programs (compressed) that run under the emulator. We include their list with the emulator’s instruction package.

In the third—and final—part of the descriptions of ZX Spectrum emulators, we will present programs that emulate the Z-80 processor and an algorithm for creating fast decoding of that processor’s mnemonics.

WILL