![]() ![]() The 128Ke has the extra memory configurations of the +2A/+3. RAM banks 1,3,4,6 and most of 7 are used for the silicon disc the rest of 7 contains editor scratchpads. | ROM 0 | ROM 1 | Either ROM may be switched in. | Bank 2 | Any one of these pages may be switched in. ROM 0 is the 128k editor and menu system ROM 1 contains 48K BASIC. Bit 5: If set, memory paging will be disabled and further output to this port will be ignored until the computer is reset.Ġxffff +-+-+-+-+-+-+-+-+ Note that this does not affect the memory between 0x4000 and 0x7fff, which is always bank 5. Bit 4: ROM select. The normal screen is in bank 5, whilst the shadow screen is in bank 7. The byte output will be interpreted as follows: Bits 0-2: RAM page (0-7) to map into memory at 0xc000. Bit 3: Select normal (0) or shadow (1) screen to be displayed. Reading from 0x7ffd produces no special results: floating bus values will be returned as would be returned from any other port not attached to any hardware. #ZX SPECTRUM 128K GAMES2GIRLS CODE#If normal interrupt code is to run, then the system variable at 0x5b5c (23388) must be kept updated with the last value sent to port 0x7ffd. When memory is being paged, interrupts should be disabled and the stack should be in an area which is not going to change. However, 0x7ffd should be used if at all possible to avoid conflicts with other hardware. As normal on Sinclair hardware, the port address is in fact only partially decoded and the hardware will respond to any port address with bits 1 and 15 reset. The additional memory features of the 128Ke are controlled to by writes to port 0x7ffd. The ULA bug which causes snow when I is set to point to contended memory still occurs, and also appears to crash the machine shortly after I is set to point to contended memory. Note that this means that there are 70908 T states per frame, and the '50 Hz' interrupt occurs at 50.01 Hz, as compared with 50.08 Hz on the 48K machine. 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, 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 128Ke is similar to the 48K machine, but with extra memory accessed by paging it into the top 16K of RAM. This reference is based on the Spectrum 128 reference from the FAQ. ![]() It can be built in hardware by modifying a Spectrum +2A. The 128Ke is an 'ideal' Spectrum 128 that eliminates these bugs and provides maximum compatibility with existing 48K and 128K software. Connected to a 1084S-D1 monitor (the best analog computer monitor ever made, hands off) over composite video.Each of the official Spectrum 128 models (MkI, MkII, +2, +2A, +3) had hardware bugs and compatibility issues.Connected to the ZX Spectrum “ear” input jack. Connected to a pre-amp mixer table with proper stereo and mono cables.Raspberry Pi with a USB sound adapter for better quality, volume maxed, using the playtape tool, from the tape2wav utilities, to play TZX files directly to the sound output.It uses PWM fed into a low pass filter to produce analogue audio), and the ZX Spectrum didn’t like it.Īfter spending some time fiddling with different setups, we finally got one right: Volume was too low, and worse, the BCM2835’s PWM sound quality was terrible (the RPi doesn’t have a DAC. We tried a Raspberry Pi for the job but it didn’t work either. Either the volume was too low, or the mono cable wouldn’t work with the phone jack. Long story short, most mobile phones we tried didn’t work. One is the tape leads, which need to be mono, not the commonly available stereo ones we have today, and the other is still the volume and pitch of the audio. We do have to worry about other things though. Instead we decode and “play” TZX files (a common file format for preserving computer tapes of the ZX Spectrum and C64), or simply play a WAV audio file, from a modern computer or a mobile phone’s sound output directly to the ZX Spectrum modem input jack, which means that we don’t have to worry about the tape quality or the azimuth anymore. Today, however, we don’t use tape players or cassettes anymore. ![]()
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