The Commodore Plus/4 is Commodore's first entry into the top level home/very small business bracket. Commodore said that it wasn't suitable for running a business but went on to say that it could be used in certain applications for a 'professional' person. This is one of the most honest statements that I have heard a computer company say on the subject of the business use of a home computer, Clive Sinclair once said that you could run a power station on a ZX80 (1K RAM, 4K ROM, and no keyboard)!!!

Where this business subject comes from is the four built in software packages - wordprocessor, spreadsheet, database and graphics - hence Plus/4.

Externally the Plus/4 is a gunmetal coloured wedge shaped box with a keyboard taking up most of the room on the top and ports and interfaces taking up the whole of the back and sides. Now it becomes obvious why Commodore opted for the smaller type of connector instead of keeping the same type as thay have for ages. If the normal 'chunky' type edge connectors and D sockets were used there would not be enough room around the edge of the machine.

The keyboard excells even Commodore's beautiful quality although some people that have used it express reservations when they first get to dabble with it. However, after a period of use everybody loves it.

The keyboard is very similar to the SX-64, and is angled, sculptured, and curved. This makes typing on it a real dream. The layout consists of 68 keys, 60 of which are normal and four function keys above the top row and four cursor control keys arranged in a cross formation. One odd thing about these keys is their shape, they look like arrows - the way the arrow is pointing indicates the direction that the cursor will go in.

The ports around the back and sides of the box show a departure from the 64/Vic stable. The Vic and C64 had almost identical I/O.

Most things that are left have been changed: The cartridge/expansion port has been reduced in size to stop people shoving C64 cartridges into it. It is unknown whether the highly advanced structure of the C64's slot is duplicated with the facility for second processors etc. But given the nature of the machine as a small system/serious device, this is more than a distinct possibility.

ROMS, these were first implemented on the BBC micro some years ago and computers are starting to get these featured. Commodore call them 'Function key packages'. The reason for this rather strange name is that when the machine boots up, it checks to see if there are any ROMs attached. If there is then it will assign each ROM to a function key. The internal software uses this system so pressing F1 gets you into it. If the ROMs are removed the function key goes back to its original state. External ROMs will go on F2. It is unknown how many ROM cartridges can be attached to the machine at once, but the complexities of the memory management system built into the Plus/4 could easily handle several.

The two D9 connectors of the C64 have been dispenced with and replaced with mini DIN connectors. This means you can only buy Commodore's joysticks. Commodore joysticks are not the best things in the world, even their new 'hi-tec' style ones.

The cassette recorder socket is also a mini DIN connector, this is because the new C16 cassette deck is different to the old tape decks. The Plus/4 is at its best with disk drives, including the new high speed ones intended for this new range of machines.

Thankfully Commodore have left the serial bus, and the audio/video connector alone. All of Commodore's exsiting peripherals, that use these ports, will work straight off, so there are already printers and disk drives available for the machine. Though it may be worth the wait to get hold of their new disks which use the cartridge port and are a lot faster than the old ones.

Moving on to the internal hardware reveals some surprises. Most of the insides are driven via one big chip. Called either the 7501 or the TED chip depending on your inclination, it combines a 6510 processor at 2MHz with a sound generator, timers, input/output, memory banking, and graphics generation. In all it has 19 registers to control things.

Sound ability is as good as can be expected although it only has two channels. These can be two sound channels or one sound and one noise (for special effects). Nearly all the advanced sound features of the SID chip have been left out like ADSR, filtering and modulation.

Graphics ability is superb. It is natural that this will be compared with the Commodore 64 as there are a lot of similarities in spec, the graphics are different and there are currently two schools of thought as to which is better the C64 or the Plus/4.

The big difference is sprites. These wonderful things that make games programming easy have been chopped from the Plus/4. In their place is a software simulation of them from Basic where you can extract an area of the screen and store it in a string. This string can then be recalled and put back on the screen at any point. There are also other options to manipulate these objects, but they are not true sprites, a large 120 byte object takes about a quarter of a second to write to the screen.

The trade-off against sprites is more colour. The screen of the Plus/4 can have 128 colours (121 excluding black) made up of 16 colours, 8 luminence levels, and flashing. Screen size is 40 x 25 text with four other graphics modes. The other graphics modes are 320 x 200 with the previously mentioned 128 colours being used in a colour map system, and 160 x 200 in a multicolour form. Both hi-res screens have an option to leave four text lines at the bottom of the screen. There are some other graphics modes and options but these are only available by POKEing. UDGs are obtained by POKEing and manipulation of registers.

The manual gives no hint of these although thay are very straightforward to obtain. When playing with UDGs one other feature becomes apparent. A character generator is 2K long, (256 x 8 bytes) the Plus/4s is only 1K long, how come? Well, the long and short of it is that the Plus/4s uses a hardware reverse field attribute. The top bit of the current character displayed indicates whether it is inverted or not. This has some advantages and disadvantages.

The advantage is in memory comsumption. The disadvantages are that you can only have 128 UDGs, and flashing works in a rather strange way. A reverse field space is shown as a black square, when you flash it instead of getting a flashing square nothing happens. This is quite confusing until you realise that a flashing space doesn't change.

Other modes not documented include Extended Background Colour mode, which gives you different backgrond colours as well as foreground colours, and multicolour characters where each character can be made up out of a number of colours. There may be others but I must wait until I get a technical manual to find them out.

This brings me onto another point. The Basic is ideal for an inexperienced user or an experienced Basic user, but what about us machine code hacks and people that wouldn't use Basic if they were paid to?

The answer is TEDMON this is a full feature assembler, disassembler, monitor and debugger. It is similar to Extramon and is very good indeed. This makes writing assembly language very easy as you already have most of the development software built in.

The monitor can also be called by using the reset button. This is a great feature and is a little recess at the side. Press it in and the machine goes back to its power on state - memory contents are preserved but it is awkward to get at them. The beauty of it all is when you keep the STOP key pressed down at the same time as you press in the reset key. The computer jumps into the monitor, key in 'X' (for eXit) and you are back in Basic. Complete with an intact program.

The Manual is excellent and way past Commodore's usual standard. It is informative and instructional for the first time user. For the experienced person there are memory maps and register details.

The Plus/4 scores over its little brother the C16 by having 64K of memory, now comes the good bit - the Basic has built in memory banking so that you can use the extra memory to the full - 60K! When using Hi-res this only cuts you down to 50K. Compare that to a BBC which leaves you with a fifth of that after hi-res has taken its chunk out. This mammoth (sorry, elefantine!) memory will mean that there should be a lot of huge advantages and great arcade games on the market to use this.

The Basic is identical to the C16 and all I said last month applies here. This is the computer of todays excellent Basic, keyboard, software built in, and best of all a vast amount of user memory. The problem is whether it is worth it at the price - 299. This is well below the BBC with which it is comparable. But then the BBC always was overpriced. Only time will tell with this computer, as it is carving a new area in the market.