Vectrex Memory Map

The 68A09 can address memory between $0000 to $FFFF (65Kb).

The ports of the 6522 programmable interface adapter (PIA) have been mapped into the memory space beginning at $D000.

A PIA port is selected by the setting of address bits 3 to 0 (the least significant address byte). The setting of address bits 11 to 4 (the two middle bytes) are ignored. As a result, $D12F, $D6AF or $DFFF is the same as $D00F - only bits 15 to 11 (which is a hex '$D') and bits 3 to '0').

The Vectrex memory has been mapped as follows:

Address Range	Size	Description

$0000 - $7FFF	32 kb	Reserved for game Cartridge ROM (read only)

$C800 - $CBFF	1 kb	Static RAM (read or write)

$C800 - $C87F	128 b	Reserved for RUM
$C880 - $CBFF	896 b	Reserved for game logic

$Dxx0 - $DxxF	16 b	The Programmable Interface Adapter (read or write)

$E000 - $EFFF	4 kb	Reserved for Mine Storm (read only)

$F000 - $FFFF	4 kb	Reserved for the RUM (read only)

The 68A09 has reserved the highest 16 bytes of memory for its various vectors:

Address Range	Description

$FFF0 - $FFF1	Reserved

$FFF2 - $FFF3	Vector to the Software Interrupt #3 (SWI3) Handler

$FFF4 - $FFF5	Vector to the Software Interrupt #2 (SWI2) Handler

$FFF6 - $FFF7	Vector to the Fast Interrupt Request (FIRQ) Handler

$FFF8 - $FFF9	Vector to the Maskable Interrupt (IRQ) Handler

$FFFA - $FFFB	Vector to the Software Interrupt (SWI) Handler

$FFFC - $FFFD	Vector to the Non-Maskable Interrupt (NMI) Handler

$FFFE - $FFFF	Reset Vector