Issue 1.0 Issue 1.1
The MK14E Expansion Board carries a 16K EPROM and 32K RAM, these can be configured to allow NIBL-E to be run on the MK14E. The board also includes extra address decoding that can be used to add e.g. additional I/O devices, the unused space on the board has been laid out as a prototyping area for this purpose.
The board has now been upgraded (to Issue 1.1) with an additional 16K of EPROM which can run e.g.NIBL-FP.
Memory
The memory space is split into four 4K pages and one 16K block. The upper 16K block is always occupied by the top half of RAM IC2. The lower 4K pages can be configured to be either RAM (IC2) or EPROM (IC1).
Link 1 enables/disables Page 0 so that the memory and I/O on the MK14E Mainboard can still be used (it is normally 'made' and needs to be cut if you wish to use the resources on the MK14E Mainboard).
This allows NIBL-E to run in Page 1 (from EPROM), then a number of 4K RAM pages are available above that for NIBL-E programs.
An additional address decoder (IC6) is normally configured to provide eight 128byte blocks between 0800 and 0C00 that can be used to drive additional I/O devices. To disable MK14E Mainboard devices tie the output to the EXT I/O signal on the backplane. If multiple devices are added then use diodes to combine the EXT I/O signals. Links 2-7 can be cut allowing the decoder to be wired differently if required.
The Issue 1.1 board has an additional 16K EPROM (IC7) that can be configured by link LK8 to sit at either $8000 or $C000.
Note: neither board is not compatible with an original MK14 because the upper 4 address lines (A12-15) are not available.
Schematic
Bill Of Materials
Blank PCB
