Tyzack VSD Main


We never got around to painting this in glorious VSD colours. The keyboard is from the Sony HP-F9P which we always preferred above anything else, the keyboard enclosure is from the P2000C. The steel casing was custom made.


Top contains a Toshiba HX-10 for 48T keyboard control and MIDI, bottom is the main VG8230.

Main PCB

Philips VG8230 with MSX2+ video chip, MSXDOS2 ROM and Tyzack VSD extensions

Main memory

DRAM extension (left top — 256kB) and 16kB SRAM "ROM"

The SRAM is writable at boot, at which point it is loaded with TYMOS and set to read-only. Tyzack will then reboot and see it as ROM, allowing for easy system upgrades which still run as ROMs.

Main extension PCB

DRAM controller-extension (left — 64kB ⇒ 256kB), A/D for Casia Printer Scanner (top right) and subsystem I/O (bottom right)

Main 2nd processor ROM

Very small boot ROM for sub system

Main 2nd processor I/O

VSD communications (left), 48T interface and MIDI interface (AY-3-1015 UART). Top left it says "sequencer". This is where, according to some drawings, we intended to connect a VG8020. I can't remember if we had one or knew someone that would sell us one. There isn't a VG8020 in the Tyzack archive.

Note (added 220625): a picture from the archive shows we did have a VG8020.

Tyzack VSD Sub-Main


Previously known as the 64M, now painted in VSD colours.


Quite empty, compared to when it was the 64M

Video digitizer

Originally a black and white digitizer in the 64M, this was modified to add a 3-bit A/D. The additional memory was just stacked, as we did a lot in those days.

Video digitizer

A/D converter and additional control logic for video digitizer


Main board and I/O


Main I/O (8255, bottom) and Speech synthesizer (SPO256-AL2, lower right) and data bus buffer board (top right)


Sound board (missing!), old VSD FIFO board (only used for some control logic, FIFOs are absent) and new VSD communication board (right).

Tyzack VSD Sampler


A Philips P2000C in Tyzack-black.

Sampler I/O PCB

Top left: analog inputs and outputs. Bottom left: 8255 with A/D and D/A converters. Right: typical 3-chip Tyzack VSD interconnect board that replaced the 64M's 40105 FIFOs.

Sampler sub-system running

The sampler (a Philips P2000-C) boots from CP/M into a loader program. The TYMOS subsystem is then downloaded from the main system.

Old pics