The additional memory features of the 128K/+2 are controlled to by writes to port 0x7ffd. To point to contended memory still occurs, and also appears to crash the machine shortly after I is set to point to contended memory. The ULA bug which causes snow when I is set Note that this means that there are 70908 T states per frame, and the '50 Hz' interrupt occurs at 50.01 Hz, as compared As with the 48K machine, on some machines all timings (including contended memory timings) are one T state later. To modify the border at the position of the first byte of the screen (see the 48K ZX Spectrum section for details), the OUT must finish after 14365, 14366, 14367 or 14368 T states have passed since interrupt. There are 63 scanlines before the television picture, as opposed to 64.There are 311 scanlines per frame, as opposed to 312.There are 228 T-states per scanline, as opposed to 224.The main processor runs at 3.54690 MHz, as opposed to 3.50000 MHz.The 128K machine is similar to the 48K machine, but with extra memory accessed by paging it into the top 16K of RAM. Several original UserĪnd Technical Manuals are available - these are listed in the May find links to additional information elsewhere in this FAQ, or to other reference documents. Each of these may have several sub-sections. This section is broken into two parts: The ZX Spectrum 128K / +2 and
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |