Universal prototyping card

I would like to present a prototyping card for the Apple II computer,which I designed and have been using for some time.This card comes in handy when I want to quickly build or design a new device.It can also be used to construct other cards—for example,based on a schematic diagram.Furthermore, it allows for the execution of custom code during the computer's startup process.No additional tools are required to write programs;the built-in ROM monitor and/or BASIC are sufficient.The card is ideally suited for creating or testing software for any Apple II expansion.It is equipped with 8 KB of memory divided into four banks of 2 KB each.These banks can be switched via software; they are mapped to the $C800–$CFFF address range.A 256-byte segment of the fourth bank remains permanently visible in the $Cn00–$CnFF range.Bank switching is performed via software.After a system reset, writing to the card is disabled, and the memory in the $C800–$CFFF range is disconnected.It can easily be unlocked via software to enable writing.Once unlocked, the card behaves like standard RAM,allowing for free modification of its contents using, for instance, the built-in monitor, BASIC, or an assembler.Any access to address $CFFF causes the card to disconnect from the $C800–$CFFF range;however, it remains visible in the $Cn00–$CnFF area (where *n* represents the slot number).

The card retains its contents after power is turned off and does not require an additional power source to maintain the data.