Romantic Robot’s MULTIFACE ONE follows in the footsteps of earlier FAST-SAVE interfaces such as INTERFACE III and MIRAGE, but incorporates extra facilities. It provides an automatic SAVE facility for cassette, Microdrive, Wafadrive and various disk drive based Spectrum systems, features a Kempston type joystick interface and has a composite video output connection.
These three ingredients improve the performance of the Spectrum by providing a more versatile storage interface, a port for the obligatory joystick and a crisper screen picture. MULTIFACE ONE supports the OPUS DISCOVERY and BETA disk interfaces directly and other drives can be accommodated by saving programs to tape in a manageable format. These can then be loaded without MULTIFACE ONE into the computer and copied to disk.
The unit plugs in as usual onto the edge connector; the joystick is connected to the 9 way joystick plug on the lefthand side and the video cable to the phono plug on the righthand side of the interface. With a Microdrive system the MULTIFACE ONE should be plugged in at the back of the INTERFACE 1 unit, but all other storage devices, WAFADRIVE, OPUS and BETA, must be connected to the extension port of MULTIFACE ONE. All software functions are initialised by pressing the ubiquitous red pushbutton.
The joystick interface is Kempston compatible, which means it is port mapped to address 31. The joystick function can be checked by pressing the red button and then SYMBOL SHIFT and A which should cause the data values to appear at the bottom right of the screen when the joystick is waggled. For the BETA disk interface the Kempston joystick interface must be disabled as it interferes with the disk drive operation. This is done by opening the rear cover and cutting a wire link close to the joystick connector.
The video output is not generated by MULTIFACE ONE, but is taken directly from the Spectrum’s edge connector. This means some Spectrum owners may not find any signal on the output of their unit as it seems some machines do not have the video signal available at the edge connector. Some Spectrum owners may find the signal very weak and noisy and see no improvement in picture quality. The familiar dot crawl will persist, as the video signal is generated from intermodulation of the colour carrier frequencies required for the standard PAL video signal. The quality of even a perfect PAL composite signal will never match that obtained with the separate RGB signals, but composite video provides an improvement in picture sharpness at least.
The save facility is obtained by pressing the red button. This can be done at any time, regardless of the program running. MULTIFACE ONE freezes the current program and displays a list of Options on the bottom two lines of the screen. EXIT provides an exit from MULTIFACE ONE and the program. This allows you to study, alter or customise the program but only on the condition that the computer doesn’t crash on exit, which depends on the existence of standard system variables. RETURN gives the control back to the current program. SAVE initiates the save routine for screens or programs. POKE provides a facility to POKE and PEEK any part of the Spectrum’s memory.
Selecting SAVE generates a prompt for the file name, which can be 9 characters long. If only ENTER is pressed the program automatically enters RUN. With the BETA drive the name is 7 characters long and ENTER on its own will provide the name BOOT.
Once the filename has been selected a menu appears: SCREEN saves a screen on its own; PROGRAM saves both screen and program and is the default setting. Then you need to specify the device you want to save to which can be TAPE. CARTRIDGE, WAFER or DISC. MULTIFACE ONE automatically detects if OPUS DISCOVERY or BETA is connected and follows the correct procedure. The program or screen is then saved to the selected storage device.
Programs are always saved in four parts; a BASIC loader, the main code, the screen and the operating code. MULTIFACE saves the contents of the computer (the RAM IMAGE) in a compressed form. There is an abort facility at every stage of the process — BREAK brings you back to the current menu. In most cases MULTIFACE ONE need not be present to reload the programs it has been used to save. The only disadvantage is the distortion of the top third of the screen, which usually gets updated by the program anyway.
Typically, a 16K program occupies 53 sectors (about 13K) and loads within 10 seconds on a BETA drive. This compares favourably with the MAGIC BUTTON facility of the BETA itself, which saves the whole 48K, without compression, onto 192 sectors. If you want to save space you have to name the file and copy it to another disk so that several programs can be stacked. MAGIC BUTTON only operates with empty single sided formatted disks. MULTIFACE ONE can store up to 24 16K programs onto a doublesided 40 track disk without renaming and recopying files,
MULTIFACE ONE has 8K ROM for its own software and 8K RAM as buffer area. The RAM can be used to store data and machine code routines, utilities, tools and so on, if required. The RAM sits below the screen area and must be paged for access. This can only be done in machine code.
MULTIFACE ONE performs well with all the storage devices listed. The compression technique assures economic saving and fast loading of any program. The system is well protected against erroneous usage with different error reports for the different systems. An extra facility, JUMP, should be implemented quite soon and will allow users to JUMP to a specific location in memory and execute code beginning at that address. Useful if you have a Disassembler lurking in memory, perhaps... Extensions to the PEEK and POKE functions are also planned — at present the facility only works in decimal notation, but the upgraded unit will offer a Hex display option and be capable of revealing the contents of the Z80 registers. Direct compatibility with the Kempston KDOS system is also planned for the future. In all, a worthwhile buy, especially for owners of fast storage devices.
Producer: Romantic Robot