Paul:

A compact FLASH card is the type of storage used in digital cameras. They are 35mm x 42mm x 3mm thick. The socket device is quite small as well. THESE ARE MADE FOR PORTABLE APPLICATION. Tape drives and floppy drives are not very portable.

There is what a compact flash card looks like:


Here is what an OEM type socket for the card looks like:


If you use a compact flash card you may want compatibility with the PC to read and write the card for data exchange. There are any number of types of USB devices that allow you to connect a compact flash card to the USB port on your PC or laptop computer. These can be had off eBay for $12 -> $25. Here is a picture of one of these devices:


Here are some links to look at concerning prototyping and playing around with compact flash cards.

http://www.sissom.org/portdigi/prototype.html
http://barrymichels.com/ide/index.php
http://www.algonet.se/~andersel/other.html


Most others that are messing around with connecting storage devices to 8051's are interfacing either CDROMS or HARD DRIVES and they are using the IDE interface. This is a doable project BUT the work to do it is almost the same as connecting and accessing a compact flash card!!

You should already know that floppy disks commonly hold 1.44MBytes. (There are some styles that hold 2.88MBytes). The smallest floppy disk drives are the types that attach to a notebook computer. You may have seen these. Building an inteface to a floppy drive, particularly if you want the disks to be reliably read in a PC computer will require you to interface a floppy disk controller chip between the disk drive and the 8051. Today most companies that made floppy disk controller chips have discontinued the standalone chips and those that still make them are making things called "Super IO Chips" which are part of the chip sets that go on PC motherboards. If you can manage to find a standalone floppy disk controller chip you have to be able to support quite complex software to run it and since the have no buffering you have to transfer data to/from them at real time disk speeds.

A tape capacity is really variable depending upon the type of medium that you elect to use. There are the DAT type cartridges (1, 4 & 8 Gbytes), TRAVAN, QIC types plus others. In order to use a tape cartridge you will need to acquire a tape drive of some type. There are many types of interfaces to these including PARALLEL PORT, IDE, and SCSI. All types could be connected to an 8051 but tape drives do not lend themselves to updates with small blocks of data. To get a tape drive going at speed it will suck up data or spew it to you rather fast. Any sized memory bank that you can hang onto the side of an 8051 just is not going to work well to supply data to/from your application.

I am not saying that you are stupid. I said that trying to connect a floppy disk drive or a tape drive to an 8052 is a stupid idea. I base that judgement on years of experience in electronics that spans almost 35 years. This is of course MY opinion. You can choose to see things anyway that you want.

I think if you look at the compact flash carefully you will see that it is the "today" way to do the job with an embedded portable product. If you are going to spend time learning something why not apply your energy to something forward looking. Experience gained in this way could very well lead to money in your pocket in the future. I can assure you that you will spend at least as much or more time messing around with getting a floppy disk drive or a tape drive interfaced to an 8051 as you would spend getting a compact flash card interfaced. And then in the end the learning experience will be about the same for either of the projects.

Michael Karas