--- title: "ZX emulators for QL and PC" type: "article" slug: "zx-emulators-for-ql-and-pc" url: "http://localhost/article/zx-emulators-for-ql-and-pc/" markdown_url: "http://localhost/article/zx-emulators-for-ql-and-pc.md" published_at: "2026-11-09T22:33:15+00:00" modified_at: "2026-11-09T22:33:15+00:00" featured_image: url: "http://localhost/wp-content/uploads/2022/04/20230809-041332.jpg" excerpt: "Many people owning a QL or PC nowadays may have been using a smaller Sinclair machine (ZX81 or ZX Spectrum) in the past. Fully overwhelmed by the exciting technical features of the more modern QL or PC, they may also have gotten rid of their good-old machines. And retrospective regrets may have occured later, as…" post_tag: - name: "Emulation" slug: "emulation" taxonomy: "post_tag" url: "http://localhost/tag/emulation/" - name: "QL" slug: "ql" taxonomy: "post_tag" url: "http://localhost/tag/ql/" - name: "ZX Spectrum" slug: "zx-spectrum" taxonomy: "post_tag" url: "http://localhost/tag/zx-spectrum/" - name: "ZX81" slug: "zx81" taxonomy: "post_tag" url: "http://localhost/tag/zx81/" model: - name: "Sinclair QL" slug: "sinclair-ql" taxonomy: "model" url: "http://localhost/model/sinclair-ql/" - name: "Sinclair ZX Spectrum" slug: "zxspectrum" taxonomy: "model" url: "http://localhost/model/zxspectrum/" - name: "Sinclair ZX81" slug: "zx81" taxonomy: "model" url: "http://localhost/model/zx81/" indiv: - name: "Carlo Delhez" slug: "carlo-delhez" taxonomy: "indiv" url: "http://localhost/indiv/carlo-delhez/" genre: - name: "Emulation" slug: "emulation" taxonomy: "genre" url: "http://localhost/type/emulation/" publication: "Update Magazine" publication_r: id: 10283 title: "Update Magazine" type: "periodical" url: "http://localhost/periodical/update-magazine/" authors: "Carlo Delhez" issues_articles: - id: 26505 title: "Update July 1992" type: "issue" url: "http://localhost/issue/ts-2068-up-date-july-1992/" pages: "44-46" pubdate: "July 1992" archive_link: false volumeissue: "vn" --- # ZX emulators for QL and PC Many people owning a QL or PC nowadays may have been using a smaller Sinclair machine (ZX81 or ZX Spectrum) in the past. Fully overwhelmed by the exciting technical features of the more modern QL or PC, they may also have gotten rid of their good-old machines. And retrospective regrets may have occured later, as these small machines weren’t so bad after all! Fortunately, there now exist programs which allow you to work with the ZX81 and ZX Spectrum again, yet this time within the safe environment of your modern and fast QL or PC: three different emulators turn your QL into a ZX81 or into a ZX Spectrum and your PC into a ZX81. The three emulators are called ‘XTricator’ (ZX81 in QL), ‘Spectator’ (ZX Spectrum in QL) and ‘XTender’ (ZX81 in PC), respectively, and are distributed on a ShareWare basis. Let me first expand a little on the way the emulators are working. As an example, ‘XTricator’ emulates a ZX81 with Z80 processor on a QL with 68000 processor. So, the emulator must understand the Z80 machine code language and be able to convert any Z80 instruction (over 700 exist!) into a sequence of 68000 instructions which have the same effect. Obviously, this needs to be done real-time and as fast as possible for maximum performance. The Z80 (8-bits) can handle at most 64k of memory, so the emulator also allocates a block of this size in the QL memory. Once the entire Z80 instruction set can be interpreted by the emulator, the ROM of the original computer can be copied into the allocated memory block and be executed as a more or less arbitrary piece of Z80 software. Next step is to consider the specific hardware features of the original computer. Nobody can use a computer without keyboard, screen, tape recorder etc. So, another part of the emulator takes care of hardware compatibility. For example, it reads the QL keyboard and sends the information about any keys being pressed in the proper way to the input/output lines of the emulated Z80. Meanwhile, it grabs the ZX81 screen with all its peculiarities and transports it to the QL display. Mind you, all this (and more) needs to be done in a flash and be repeated continuously, so that the person using the emulator gets the distinct impression of working with a real ZX81. Naturally, a similar scheme applies for the other two emulators. XTricator and Spectator emulate a 64k ZX81 and 48k Spectrum on the QL this way. For both programs you need a QL with a least 256k RAM, a 3.5″ diskdrive, and preferably ToolKit-2 and the pointer environment (e.g. QPAC2). On a 8 MHz 68008 QL, the emulators can reach an effective Z80 frequency of about 0.3 MHz, i.e. 35% of the original ZX81 speed (in SLOW) or 9% of the original ZX Spectrum speed. On a 16 MHz 68000 QL, the frequency leaps up to 1.2 MHz, i.e. 150% of the original ZX81 speed and 35% of the ZX Spectrum speed. From these numbers one can see that a QL with Gold Card or Atari-QL is essential for reasonable operating speed of Spectator. Both XTricator and Spectator are activated as jobs and are really multitasking: neither keyboard input nor screen output interfere with other jobs, provided the pointer environment is resident. XTender is very similar to XTricator, but intended for MS/DOS machines. Since the machine code language of the 8088/8086 series is very similar to the Z80, the emulator performance is much better. Even on a 8 MHz XT, a speed of 60% of the original ZX81 can be teached. Moreover, the speed increases rapidly when using faster machines. For example, on a 33 MHz 386dx, a speed of about 900% can be reached (over 7 MHz Z80 emulation frequency, 9 times ZX81 speed!). XTender will work on a PC (8088/86/286/386/486…) with at least 256k of memory, DOS 2.0 or higher, and with Hercules, CGA, EGA or VGA graphical adapter. Some specific features of XTricator and XTender: they both emulate a 64k ZX81, tape commands are redirected to disk drives (or hard disk), a set of new commands has been implemented for communication to the QL/PC hardware directly from ZX81 Basic, ZX81 high resolution offered by many games is emulated, ZX81 printer output is redirected to QL serial port, QL/PC keyboard is fully mapped on the ZX81 keyboard, graphical help screen with scanned image of ZX81 keyboard activated by a simple keypress, additional features include SuperBreak, screen invert and Z80 reset by keypresses etc. Spectator emulates a 48k ZX Spectrum with ZX Interface 1 (issue 2). Full colour and flash attribute emulation in QL mode 8. The tape commands of Spectrum Basic are redirected to floppy disk. Of the ZX Interface 1, the Shadow ROM Basic extensions, the microdrive commands and the serial RS232 interface are emulated properly (the LAN will follow later). The QL keyboard is mapped fully on the Spectrum keyboard and a graphical help screen with the Spectrum keyboard is activated by a keypress. Also keypresses are available for SuperBreak, screen invert and Z80 reset. In fact: too many feature to mention here! All three emulators have been tested thoroughly with hundreds of existing ZX81 and Spectrum programs (mostly commercially marketed games and utilities written in machine code). The vast majority of programs worked just fine. Only few programs fail to run on the emulator, but generally these programs are to blame (e.g. because of excessive piracy protection), not the emulator! ZX81 programs were not so well protected as Spectrum programs, and 99 out of 100 existing ZX81 programs will work! For the Spectrum, this number is currently about 95 out of 100. The emulators are supplied with extensive manuals as 80-column ASCII text files. As said before, the programs are distributed on a ShareWare basis. To obtain a try-out version of all three programs, send eight DS/DD 3.5″ brand disks to me (2 for XTricator, 4 for Spectator, 2 for XTender). I will always keep half the number of disks to cover my p&p. Ofcourse, you can also order registered versions immediately. Registration costs 50 Dutch Guilders per emulator (this is about $ 25, but for reasons of exchange I accept cheques in Dutch Guilders only)*. For this fee, you will get the most recent version of the emulator on a 3.5″ DS/DD 3M disk, a laserprinted copy of the manual, you will receive one update of the emulators for free and are informed about later releases. For XTricator and XTender, you also get access to a huge ZX81 library; the first disk with 80 programs is dispatched together with your registered copy. For Spectator, you will get a number of disk conversion utilities with your registered copy, which allow you to convert programs on original Beta, Disciple and Opus Disk to QL files which can be loaded directly into the emulator. A conversion utility for Spectrum microcartridges is in development. And last but not least: when you register, you support my efforts so that more programs of this kind may appear in the future! For questions, try-out versions or registration, please write to me at the address below. Carlo Delhez, Emmastraat 3, 4651 BV Steenbergen, Netherlands. ** or cash in any currency, but please add 15% exchange costs.*