|★ HARDWARE ★ PERIPHERIQUES ★ AMRAM ★|
|Interface Rom - Amram|Amstrad Action)||Hardware Peripheriques|
Silicon Systems has produced a peripheral that will have ROM users (and abusers) applauding. It is a tool that will aid eprom programmers to save time and develop their software.
What is this magical device? It's sideways ram: an interface that plugs into your Amstrad and behaves as a ROM when in fact it is RAM.
Confused? You probably know that ROM means "read-only memory" - the computer cannot write over or change data on this sort of chip, so it's used for software you always want on hand, such as the Basic language itself. And RAM means "random-access memory", sometimes called read-write memory. The side ways-idea is that several blocks of memory can share the same addresses; a simple command shunts in one block when it's needed instead of another (see diag RAM in Problem Attic, page 24). Basic and a word-processor such as Protext are the sort of beasts that live this way. Memory addres ses involved on the CPCs are &C000 to &FFFF for upper roms - in fact the same location as the screen and 0 to &4000 for lower roms.
But why does Amram act like a ROM when it's really ram? Amram consists of two banks of 8k RAM slotted into ROM socket five, and you use the rom-enable firmware routines to access it. It behaves like a ROM until you flick its write-enable switch and a red diode glows to warn you data can now be written as well as read. The green LED shows the computer is reading Amram data.
Amram really sparkles when used with its bundled icon-driven software. You can load data from another rom, customise it (perhaps you like seeing your name in lights instead of the rom's sign-on message), and then send it to Amram. Resetting the machine won't get rid of the data held in Amram; only the other switch on Amram or switching the power off will kill it.
Of course altering the data held in other roms and saving it to Amram could be just a gimmick, unless you wanted, say, to alter some of the defaults :n Protext. The real use of sideways RAM is for developing your own ROM software. Create your own program then save it to Amram it is now simple to test it rather than wasting time and eproms. I discovered this the hard way: after each modification of my ROM software I had to blow an eprom to test it. So I'd thoroughly recommend Amram.