Changes
The '''standard''' memory expansions are often credited to [[Dk'tronics]] and [[Dobbertin]] (not sure which company initially developed it though). There's also an '''extended standard''' which may be credited to probably [[YarekRAM7]] (seen at least in comp.sys.amstrad.8bit FAQ v0.90, 11 september 1997) or [[RAM7Yarek]] (not sure who came first here, too).
== Technical ==
Expansions bigger than 512K extend that above standard. The LSBs of the 64K bank number is kept in D5-D3 data bits (as above), the MSBs of the 64K bank number are in A10-A8 address bits. Typically in inverted form (so the first 512K block is accessed via Port 7Fxxh, the next via 7Exxh, etc.
OUT [01111aaaxxxxxxxx],11bbbscc11bbbccc
aaa = upper bits of 64K bank selection (512K-step) (A8,A9,A10 bits)
bbb = lower bits of 64K bank selection (64K-step) (D3,D4,D5 bits)
xxxxxxxx = should be set so that it doesn't conflict with other ports (*)
* [[RAM BOX]]
* [[SYMBiFACE II]] - includes (among others) 512K RAM expansion
* [[X-MEM]]
* [[Old_School_512K_RAM_Expansion]]
* [[CPC_6320_-_internal_320K_for_CPC_6128|CPC 6320 - internal 320K for CPC 6128]]
== Extended-Standard Expansions ==
* [[CPC4MBGemini]] ([[Yarek]]) (DIYShinra - PulkoTronics) - compatible with standard 512 Kbyte expansion (plus extra extended-standard 3.5 MBbyte512 Kbyte), also handles special case for Amstrad Plus ASIC
* [[RAM7 2MB memory expansion]] ([[RAM7]]) - compatible with standard 512 Kbyte expansion (plus extra extended-standard 1.5 MBbyte)
* [[CPC4MB]] ([[Yarek]]) (DIY) - compatible with standard 512 Kbyte expansion (plus extra extended-standard 3.5 MBbyte)
== Semi-Standard Expansions ==
