microbee simple compact flash interface, the beginning

Have been playing with my microbee and looking at a simple compact flash interface.

Not 100% sure if I’ll continue with it as is or alter it.\

The simple interface uses an 8 bit data bus. Downside is that it effectively halves the capacity of the compact flash, given their price and size for cpm use it isn’t really a handicap. However the interface is trivial.

I used a CF to IDE adaptor, an IDE cable, a 40 pin dil header and socket and some wire. It’s plugged into the 128k ram coreboard where the SCC would sit, if fitted.

I knocked up a simple bit of test code to see what sort of speed I could read the data from the compact flash card.

Here’s a couple of hitech screen dumps with two different CF cards. First half is a hex dump and 2nd half is ascii or hex for non printable characters.

The data rate is (very) roughly 3 sec for 25kbytes. This was with unoptimised C code and glancing at a watch for timing.

An alternative place to connect to the coreboard on the microbee is near the 34 pin floppy drive connector. Applied Technology used the same coreboard for their hard drive model and have overlaid a 40 pin connector next to the 34 pin connector. One side is used by the floppy connector but half of the pins, with all the signals needed except +5v are available by adding a 20pin single row header.

The downside of the simple 8 bit interface is that it isn’t so simple to move the CF card onto a linux/windoze system to move data back and forth without writing special drivers.

Will post up progress and info on here as I get to it.

Leave a Reply