|★ HARDWARE ★ PERIPHERIQUES ★ Advanced Eprom Expansion Board: New ROM board for Arnold|Amstrad Computer User) ★|
|Memoire - Microgenic - Advanced Eprom Expansion Board||Memoire - Microgenic - Advanced Eprom Expansion|
Board of the roms
Phil Craven can't see the wood for the chipboard
REALISING that more and more people are putting Arnold to serious work, and with sales of CPC rom-based software on the increase, Microgenic Systems has applied its considerable industrial experience and expertise to the home computer market by producing the Advanced Eprom Expansion Board.
The 7.5in x 5in unit is supplied uncased. It connects vertically to the CPC's expansion port -taking up less space at the rear of the machine than the monitor plugs - and has one through connector, allowing the use of other peripheral devices.
Because the expansion connector on the 464 is higher than the 6128's, two self-adhesive feet are provided for 464 owners with disc drives to add stability; the feet raise the level of the DDI-1 interface to that of the board's through connector.
When connected to a 6128, the board is suspended about an eighth of an inch above the desk top - higher on a 464 - and although it is very lightweight and normally stable, I can't help but wonder if an accidental strong push against the board might bend the CPC's mother board to the point of damaging it. It would take a very clumsy person, but it might be possible.
Switches are located across the top of the board in easy to use positions and the board itself is clearly printed with words and numbers, making their use obvious. A bank of eight switches allows each ROM to be enabled or disabled individually, and another switch enables or disables the entire board. A red LED indicates when the board is enabled.
The bright red Reset button is a nice feature. At first I thought it was a waste, since we are all used to using the keyboard to reset the machine, but then it occurred to me that sometimes the machine hangs up and the Ctrl/Shift/Esc method doesn't work.
So I set up that condition and, sure enough, the Reset button did the job. The alternative is to remove any disc and power down.
It is a good habit never to operate switches while power is applied to ROM boards as damage can occur, but all switches on this board are designed to be used with the power on. This means that individual roms, and even the whole board, can be switched in and out of circuit at any time without risk of damage.
The link has to be made with a soldering iron and the original link either removed or cut. Although the linking holes have been designed so that a DIL switch can be soldered in, making low and high numbered ROM banks switch-selectable, I feel that a slide-on/slide-off link would have been better.
Microgenic Systems says that most users would not require roms 8 to 15, and even this small saving helps to keep the price down. This is undoubtedly true, but the slide facility would have been better, particularly since 6128 owners - who are in the majority - can only use sockets 1 to 6, because sockets 0 and 7 are reserved for Basic and AmsDos.
The board is extremely well designed, as one would expect from a company with extensive industrial experience. All the logic chips are high speed, low powered CMOS HCT - ensuring that current drain on the CPC's power supply is negligible.
The buffered data bus and large area of ground plane - the amount of copper clad board at 0v -add to the board's overall reliability.
While the lack of slide links for ROM bank switching, and the remote possibility of damage due to clumsiness, are negative points, the excellent technical and functional design of the board with its well positioned and easy to use switches, the Reset button and the fact that its takes up virtually no desk space make it very good value.
Whether or not the lack of a casing is a plus or minus point is a matter of individual choice. Personally, it makes me feel rather clever having all those chips on display to visitors!