While confusion reigns as to whether Sinclair Research is or is not developing a replacement or upgrade with or without 128K of RAM (WHO said that...) CRASH has received at its offices a machine which at first sight appears to be the much aligned TIMEX 2068 from the United States. On closer inspection however, and with an astute reviewer pointing a joystick-battered finger in the right direction, the small PAL logo was discovered hiding in full PAL-colour on the front of the machine leaving no doubt that this was a European version of the same said brute (Nice one Mr. Holmes). In fact, it was later discovered that TIMEX of Portugal was the perpetrator of this crime (Who on earth would send CRASH a computer to review)? In their defence it must be said that they were only trying to promote their baby (a bastard by inception and certainly on closer inspection) with the hope of creating some interest here in the UK (wake up you boys and girls)! A thought crossed our minds here at Ludlow (the lights dimmed in the offices for a couple of seconds) whether this could possibly be the replacement/upgrade for existing and future Spectrum users?
The good looks of the machine certainly provoked a lot of appreciative grunts from Spectrum addicts. Th e computer squats on the table trying to cheat its own shadow and looks like some jumbo family-pack portable calculator in a neat silver metallic costume. The keyboard layout is an exact copy of the rubber-gumption Spectrum sloshboard, but sports some extra useful items such as a full length space bar and a complementary caps shift key on the righthand side. The annotation is only in mono (What happened to PAL colour?), but differentiating between the four key-modes is in fact easier than on the Spectrum due to the inverted logos for the symbol shift operations. The key-action is a lot more crisp and sharp and is a space leap for Spectrumkind, although it’s still light-years away from the full-sized, full travel keyboard standard.
To the right of the keyboard a large flap uncovers the TIMEX COMMAND CARTRIDGE ‘dock’ which will accept TIMEX specific ROM/RAM modules complete with carrying handles. These are sideways ROM/RAMS using the ingenious bank switching technique (more of this later...) and can be the carriers of autostarting commercial programs (games, utilities etc) or special languages or operating systems. To the lefthand side of the unit is located a power toggle switch (yes, no add-on required!) and further back a nine pin D type plug reveals the existence of an inbuilt joystick port, lo and behold, two joystick ports — the companion plug residing on the opposite side of the computer. Great, no fuss and worry about joystick interfaces, but wait, the software access to the joysticks is anything but standard, requiring access to ports 245 and 246. The trouble is compounded by the fact that the joysticks share these ports with the inbuilt sound generator chip. Before a read of port 246, one of the sound chip registers must be selected which will enable the free input port dedicated to the joystick. This is done by writing the correct value to the sound chip address port 245. Confused, well this means that the joystick ports can only be accessed with machine specific software or by using an extended basic command called STICK, that is if you do your own programming.
At the rear of the unit are a range of input and output ports, the most familiar being the PAL compatible UHF modulated TV output, the 9V power socket and the MIC and EAR sockets for the cassette recorder. A monitor output is provided, which delivers a composite video signal. Unlike the Spectrum, the TIMEX features three extended display modes besides the usual 32 column screen with the character size attribute mode (display mode 1). Display mode 2 provides a 24 x 64 character display (512 x 192 pixels) with one ink and one paper colour. Only fixed paper and ink colour combinations may be selected with bright on and flash disabled. If the character set is redefined by the user, up to 80 characters can be displayed per column and here, obviously, the monitor output is essential.
Display mode 3 displays a secondary screen and attribute page similar to display mode 1, only this time the display file is not at 4000H―57FFH, but at 6000H―77FFH and the attribute file not at 5800H―5AFFH but at 7800H―7AFFH.
Display mode 4 is the high colour resolution display with the same pixel resolution as mode 1 but with a choice of ink, paper, brightness and flashing for every pixel row of eight pixels. The attribute file is located at 6000H―7AFFH in this case. As last item there is a 64 pin bus expansion edge connector, which has a different pinout to the Spectrum version and so precludes any ideas of peripheral compatibility.
Having extended facilities such as joystick ports, sound generator chip and ‘dock’ memory port, the TIMEX requires a different approach to the system memory configuration. As the Z80 can only access 64K of memory at any given time, the TIMEX people have resorted to the bank switching technique. Up to 4 different banks of 64K can be accessed via the memory bank controller located at ports 252 (DATA) and 253 (ADDR). Memory is selected in 8K chunks and up to eight of these can be selected from the whole bank range as long as they are not located at the same 64K address position.
The Home bank is selected by default and contains the 16K ROM with the Basic Interpreter, routines for in- and output (graphics, keyboard, joysticks, printer, sound chip etc) and 48K of RAM with the Display files, system variables and BASIC program. This is equivalent to the structure of the Spectrum memory. The second bank is the EXROM bank which only contains an 8K ROM with the cassette in-output routines, the bank switching code and the System initialisation routines. The third bank is the DOCK bank, which serves the cartridge programs, and contains either AROS (Application oriented software) or LROS (Language oriented software) or both. The system will detect the presence of these modules and will pass control to these. Bank 4 is the EXPANSION bank. The system will support up to 2 of these (up to 253 of these with a Bus Expansion Unit) and the banks can be used for controlling intelligent devices or for memory expansion. Expanding the TIMEX machine to 128K is therefore a doddle.
As mentioned earlier, TIMEX has provided the machine with a bit more audio power with the help of a 3 channel sound generator chip extra to the normal BEEP output. The General Instrument Ay-3-8912 chip consists of a tone generator for three channels A, B and C, a noise generator and mixers. There is ample control provided for various envelope shapes, amplitude levels (up to 16 levels) and tone and noise generator combination selections either via Basic or via machine code instructions.
To access all the extra little goodies, several BASIC commands have been implemented.
SOUND reg, value; reg, value; etc.
This command controls the 15 registers of the sound chip and allows the programmer to manhandle the chip in BASIC and create a symphonic background to the graphic activities on the screen.
STICK (device type, player)
The function allows the player to read the status of the two joysticks within BASIC. The value returned can be a combination of several activities and must therefore be evaluated within ranges.
This command allows the deletion of a sequence of lines from a program (lines m to n).
This function returns t h e number of bytes of free space currently available in the Home RAM for either programs or variables.
RESET ($c) (*)
This command causes the device associated with the specified stream to be reinitialised. If a channel number is not provided, the system initialises any new devices it finds. The RESET command does the equivalent of turning the machine off, then on again.
ON ERR GOTO linenumber
ON ERR CON'T
ON ERR RESET
These statements disable the automatic program termination upon encountering an error condition. The ON ERR GOTO linenumber can capture an error with a error routine residing at the specified line and the error number and line location can be peeked at the locations 23739 and 23736. The statement number with in the line that caused the error is stored in location 23738. The ON ERR CON'T statement causes the program to resume execution at the statement in which the error originally occurred. If the command is encountered and an error has not occurred, the command is ignored.
A complete set of commands is available for accessing disk or disk-like storage devices which are present on an Expansion Bank. The Home ROM is responsible for passing the command and calling the appropriate routine in the specified Expansion Bus. These include commands such as OPEN, CLOSE, SAVE, LOAD, ERASE, MOVE, VERIFY, PRINT, INPUT and MERGE with microdrive style arguments.
Few hardware manufacturers will deny that launching a new computer without a large existing software base can cause initial sales delays, especially if the target market is games related. Timex in the States obviously underestimated this point by not ensuring full compatibility with existing Spectrum games. They rejected access to the world’s largest games software base and lost the advantage of winning several years of free software development. TIMEX of Portugal realised this and are offering an emulator cartridge to fit into the ‘dock’ port. Several ROM routines and their start addresses are different on the home bank ROM and machine code programs accessing these routines will encounter several obstacles. So many arcade games program will probably not run in the standard configuration. The emulator replaces the home ROM and provides full compatibility with the Spectrum. Several Spectrum games were tested and performed as normal with the use of the emulator.
The TIMEX computer offers an improved performance when compared to the Spectrum 48K and the Spectrum Plus, but it is about two years too late in appearing. It does not offer enough improvements to warrant users to upgrade to this machine, as there are several very exciting new computers appearing on the market. For new users the machine could prove to be a better machine than the Spectrum, although the changes will only be noticed with specially written software which will make good use of the sound generator chip, the inbuilt joystick ports and the bank switching possibilities. The major question will be what price level the machine will be offered at. At £70–80 the TIMEX would be a very good entry level computer, but no official price indications have found their way to the CRASH offices...