Sinclair ZX Spectrum 48K upgrades

Adds an internal AY or Yamaha sound generator and stereo output to a ZX Spectrum through a CPU adapter.

For this system (stated family): The seller describes the module for ZX Spectrum and compatible computers. This conservative relationship uses the original 48K page only; confirm CPU socketing, board clearance, AY-chip type, audio wiring, and exact motherboard layout.

Lotharek marks the interface discontinued. The AY chip and audio connector are not included. Plug-in installation assumes a socketed CPU; otherwise safe CPU desoldering and socket work are required. Preserve pin-1 orientation at the CPU adapter, ribbon cable, and sound-chip board, then provide the documented stereo and ULA-audio wiring.

Combines DivMMC-compatible microSD storage, 512 KB of expansion RAM, dual-AY audio, DAC modes, and configurable joystick or mouse input on the ZX expansion bus.

For this system (exact model): The upstream DivTIESUS compatibility matrix reports successful tests on ZX Spectrum 48K Issues 1, 2, 3, 3B, 4A, 4B, and 6A. BISON is a modified 512 KB implementation, so retain the seller's power and firmware instructions.

The seller exposed a login-or-register-to-buy path on 2026-07-27 and documented firmware 1.5. Power off before changing the edge connection or input mode. Automatic Sinclair-versus-Amstrad selection depends on 9 V at edge pin 3B; compatible clones without that signal need the documented modification. Firmware updates require a separate Gowin programmer and removal of the flash ROM. Prepare a separate FAT32 microSD card with the supported ESXDOS release.

An external fifteen-ROM selector for original Sinclair 48K, 128K, and grey +2 computers, controlled by one button and binary indicator LEDs.

For this system (exact model): The seller explicitly names the original Sinclair 48K. This is an external expansion-port device and should be fitted only with power removed.

The seller exposed a login-or-register-to-buy path on 2026-07-27 and explicitly limits support to original Sinclair 48K, 128K, and grey +2 machines. Power off before connecting or removing it. Confirm the exact ROM contents and any software licensing from the current unit rather than assuming every example named on the board is supplied or redistributable.

Combines DivMMC microSD storage, USB HID input, four ROM slots, snapshot storage, dual-AY audio, and DAC modes in one ZX expansion interface.

For this system (exact model): The seller lists the original ZX Spectrum 48K among its initial tested machines. Power off before fitting the edge interface or microSD card and use the current BIOS and firmware.

The seller exposed a login-or-register-to-buy path on 2026-07-27. Its published testing covers the original 48K, original 128K, Pentagon, and KRAKEN. The page says +2A and +2B compatibility still has known issues and that keyboard-mapped USB input will not work on +2A or +3 because of data-bus coupling; those models are not attached. Treat the described resistor workaround as experimental, not an installation recommendation. Follow the separate FPGA and USB-controller update procedures exactly.

Replaces the Z80 and upper 32 KB of DRAM in a ZX Spectrum 48K, Spectrum+, or Timex TC 2048 while adding AY sound.

For this system (exact model): The seller explicitly names ZX 48. Installation replaces the CPU and upper 32 KB RAM and may require bending the nearby heat sink for clearance.

The seller exposed a login-or-register-to-buy path for MAMLAS on 2026-07-27; its Z80SRAM predecessor is discontinued. MAMLAS installation is invasive: remove the original CPU and any socket, disable or remove the upper 32 KB DRAM, and solder the module directly at the CPU footprint with correct pin-1 orientation. The audio connector is not included, and a ZX Spectrum 48K heat sink may need to be bent for clearance. Do not install the module on top of its shipping or protective bottom socket. Used Z80SRAM boards should be treated as a distinct earlier revision and checked against their archived instructions.

A Xilinx CPLD module replacing specific failed gate-array chips in late ZX Spectrum 48K, 128K, and grey +2 computers.

For this system (exact model): The seller limits the 48K use to Issue 5 and Issue 6 boards fitted with ZX8401. Do not infer support for earlier issues or other ULA and gate-array packages.

The seller exposed a login-or-register-to-buy path on 2026-07-27 and gives an unusually precise chip and host list. Neither the page nor human review supplies a removal, socket, orientation, or board-revision procedure. Treat this as skilled rework and obtain exact installation instructions before buying or disturbing the original gate array.

Adds a PS/2 or PS/2-compatible USB keyboard to a ZX Spectrum 48K or Spectrum+ through an internal keyboard-interface board.

For this system (exact model): The seller explicitly names the ZX Spectrum 48K. Confirm which of the !RDFE or IOULA-based read modes the motherboard requires and do not assume the original membrane remains active.

The seller exposed a login-or-register-to-buy path on 2026-07-27. It explicitly targets the 48K and Spectrum+ and warns that the original keyboard may stop working while the adapter is installed. The two signal modes use different motherboard signals; select the documented jumper state for the exact board and change hardware only with power removed. A USB keyboard works only if it supports the PS/2 protocol through its connector.

Replaces the ULA, video RAM, upper RAM, and RF modulator in Issue 2 through 6 ZX Spectrum 48K boards while adding modern video, sound, memory, and machine modes.

For this system (exact model): The seller specifies ZX Spectrum 48K Issue 2 through 6 motherboards. The upgrade retains the real Z80 but replaces or disables several original subsystems and requires soldered control wiring.

The seller listed availability after 2026-08-31 and exposed a preorder path on 2026-07-27. Installation is invasive: remove the ULA and RF modulator, disable or remove the original DRAM, connect M1, RESET, IORQ, and RFSH at the Z80, and install the supplied RGB adapter and ribbon cable. The output is digital RGB only, not composite or YUV. Verify board issue, pin 1, wiring, case clearance, display compatibility, and the current installation guide before work.