Micro­power

similar to that used on the RAM A board and is very straight forward.

Link Block B (LKSB)     Page configuration – page number selection.

Once you have decided where you want your RAM (there’s no answer to that) the next thing is to decide whether you want the RAM as one 32K page or two 16K pages and then which pages to use (0 to 3). This is the decoding carried out at LKSB. If you choose to have two 16K pages these are assigned as page A and page B and may be placed into the memory map on pages 0 to 3. The explanation provided in the manual for this, decoding is probably the hardest part to follow. It is easy to configure your board from the examples provided but the explanation is not very clear and it took a phone call to Microcode and a long hard look at the circuit diagram before the theory emerged. The page selection uses Port FFhex to feed a latch which is linked to the buffered data bus. The low nibble of the byte provides the page read enables and the high nibble, the page write enables.

Therefore, to put your RAM as Read/​Write on pages 0 and 2, connect 1D to bit 0, 2D to bit 4, 3D to bit 2 and 4D to bit 6. This leaves the pages free for other page compatible RAN or EPROM boards.

Link Block C (LKSC)     Page configuration – page reset option

This link block is used to select which, if any, pages will be paged in on reset (including power up). If page B is required on reset then link WEB and REB to any of the Q dash pads. It is possible to have the selected page as Read only on reset in which case only the REB is connected to a Q dash pad. Hardwired Write protect (and Read protect if necessary) can be accomplished by wiring the appropriate WE and/or RE pads to the provided 0 volt pads.

Link Block D (LKSD)     Power option.

This is the beauty of the board. Up until now it can have been regarded purely as 32K of paged RAM. The power option provides the battery-backed links required to turn the RAM into something close to easily programmable/​eraseable/​changeable EPROM. Each chip in provided with a link option allowing it to be either connected to the backup supply (provided by an on-board VARTEC MEMPAK 3.6v PCB Ni-cad. Battery) or connected just to the normal +5v line of the micro. The battery can support the fully populated board for over 40 days and recharge