Simply set up a number of banks of them in memory and point to each one as you need it. Alternatively, you could redefine the character set instead. You could even mix text and graphics, redefining the letters and numbers of your font to the style of your choice, then using up the symbols and lowercase letters for aliens, zombies or whatever your game requires. To point to another set we subtract from the address at which the font is placed and place this in the two byte system variable at address The default Sinclair font for example is located at ROM address , so the system variable at address points to when the Spectrum is first switched on.
For this we simply load the bc register pair with the number we wish to print, then call :. However, since BASIC line numbers can go only as high as , this has the disadvantage of only being capable of displaying a four digit number. Fortunately, there is another method which goes much higher. Instead of calling the line number display routine we can call the routine to place the contents of the bc registers on the calculator stack, then another routine which displays the number at the top of this stack.
Just remember that the following three lines will display a number from 0 to inclusive:. To set the permanent ink, paper, brightness and flash levels we can write directly to the system variable at , then clear the screen with a call to the ROM:. The quickest and simplest way to set the border colour is to write to port The 3 least significant bits of the byte we send determine the colour, so to set the border to red:.
Port also drives the speaker and Mic socket in bits 3 and 4. However, the border effect will only last until your next call to the beeper sound routine in the ROM more on that later , so a more permanent solution is required.
To do this, we simply need to load the accumulator with the colour required and call the ROM routine at To set a permanent red border we can do this:. How can I edit the capacities and average gates for Football Champions. Any help please?? Your best bet is to use a windows emulator with debugging facilities to find the relevant bits of code and data addresses. Then use that info to break into the code on any emulator that supports this and POKE the stuff you want.
Alternately, write a small BASIC header that loads in the game code and then change the data post-load. Please could you help me. Well there are a few ways to go about it.
It would be nice to have the screen captures showing the code result. Great tutorial, congratulations! Have a look at their documentation to see how. Alternately, you can load the block of assembled code using an emulator and save a z80 snapshot or TAP file. You are commenting using your WordPress.
You are commenting using your Google account. A downloadable programming tutorial Download Now Name your own price. More information. Status Released Category Book Rating. Download Now Name your own price. Comments Log in with itch. Tender Boing days ago. Oh wait, I found the answer in Dr Logan's book :. Previous Sinclair machines, particularly the ZX80 and ZX81 had been extremely popular, but being supplied primarily as home-build kits, were aimed more at the enthusiast market than any other.
The ZX Spectrum, however, was marketed firmly at the home user when attempts at introducing it to educational institutions largely failed.
Although criticism was wide for the machine the keyboard, in particular, was derided by many in the press of the time, the 'man-in-the-street' didn't care and bought the ZX Spectrum in vast numbers, originally by mail order only. The introduction to high street stores once production had increased sufficiently to meet the demand enormous delays hampered the machine at launch solidified the market-share afforded Sinclair even further.
A huge software industry was founded around the popularity of the machine, with many companies founded in the s still in business today producing software for modern systems. The essential differences are that the keyboard is significantly improved, though still membrane based, and bears resemblance to the design developed for the QL - they are not the same, but share similarities. Additional keys were added to allow direct access to 'Extended' mode, for example, and a 'Reset' button was included, for the first time removing the need to unplug the machine completely to perform a general reset.
Please see the ZX Spectrum Reference reference page for additional information. Processor : Zilog Z80A 3. ROM : 16K. Sound : Internal 40 Ohm TV-type speaker providing 1 channel output.
Video : x pixels with 16 available colours. Power Supply : Part no. The common specifications are listed for each, with links to original documentation where available provided. Technical information for many of these models is provided on the K Reference page.
A complete, detailed, guide to ZX Spectrum emulation for both starting and advanced users. The current version is v1. The current version is v0. A Z80 Table , by Einar Saukas.
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