Dobbertin Memory Expansion
A memory expansion by the German company Dobbertin.
The Dobbertin memory expansions are compatible to the memory expansions by dk'tronics. The memory expansion came in two versions. A version with only the memory expansion, and a version with two sockets for additional rom software.
Optional two rom sockets. Each socket could be manually configured for rom 1-15
I/O port decoding is the same as Dk'tronics.
A15=0 with all other address bits can be any value. (Use 7fxx for compatibility)
Dobbertin supports all ram configs (c4-ff) as expected.
But, on a 464 with ROMs enabled and config 3 (c3 etc) is chosen we see:
&0000-&3fff: base ram &0000-&3fff &4000-&7fff: upper rom &8000-&bfff: base ram &8000-&cfff &c000-&ffff: upper rom
- For the I/O Ports, see Standard Memory Expansions.
Dobbertin supplied RDOS as a optional ROM to use the memory expansion as RAM disc with 444 KB free. They also supplied CP/M 2.2 and Plus with full support of the RAM disc. Other software using this RAM expansion: Discology, FutureOS and ParaDOS. Arnor software like Prowort and Maxam II also support the usage of the RAM disc.