IDE for C64

From: Ruud Baltissen (
Date: 1998-12-03 23:25:17

Hallo allemaal,

I just finished the HW of the interface to connect a IDE-harddisk with a C64. 
Now the testing phase starts. FYI, it is built with 7 common available ICs. As 
base of the design served the idea of John, the SCH of an interface for a 
XT-PC, one for the TRS-80 COCO and one I got from our sister organisation, the 
Sinclair User Group. Their design was completely different but that helped me 
to solve some questions I still had.

The next problem is: what to do with the whole thing? It sounds great to have a 
HD attached to your C64 but I'm going to ask you the same question that 
silenced a colegue at my office: what about the needed SW???? I think I can 
free up to 2KB in the original ROMs by removing the cassette- and 
RS232-software but I'm sure that won't do. You could add extra ROM using some 
HW-tricks but I wonder what happens with the compatibility towards an original 
Another solution is to use a C64 as Server. You can use a cartridge to load the 
actual server-SW and from that time on the C64 functions as another HD. Only 
disadvantage: not 1541 compatible.

************ = Big Idea !!!!  :-)

My third idea was to use an obselete 1541 or 1571 board as base. Add the above 
HW and change the ROM where needed. The idea is to change the ROM there where 
it starts to read the data from/ write to the disk. In this way (I hope) 
speeders like EXOS V3 and even SPEEDDOS still will run. I even hope GEOS won't 
notice the difference. The Big Idea that popped up writing the description of 
the C64-Server is to add some RAM to the board and to use this for the actual 
HD-software. In this way you can change the SW without the need to burn EPROMs 
every time.

So my first question to you is to give your opion about the 3 ideas and feel 
free to add even more!

If there is a first question, there should be at least a second. What about the 
format of the disk itself? One idea is to create a lot of D64-images but that 
would mean that a 3.5 MB HD would be sufficient to give you 20 1541-floppies. 
But before inventing the wheel again, who has some ideas? (BTW, does anybody 
know how CMD solved this?)

Groetjes, Ruud

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