APPLEBOX ACI page

APPLEBOX - the Apple-1 pages

the Apple-1
Cassette Interface Card

The Apple-1 did not have a interface "on board" to store or read programs. At the moment the computer had been developed, Steve Wozniak
of course was aware of that problem - so he integrated the slot at the edgeconnector with the most signals of the Apple-1 looped up to the slot.

This gave him the freedom to first complete the design of the computer itself and push the development of the "storage facility" ahead to a later
point in the timeline. While then testing the basic functions of the Apple-1 prototype he then searched for a cheap and simple ability to store
and read programs and then designed the Apple-1 cassette interface. This gave the user a cheap and common ability to handle the storage. You
should remember that the common storage units of those days on disk or at cards have been extreme expensive and due to the fact that Wozniak
and Jobs targeted in the general to sell their computer to students - so they of course did hunt for a cheaper solution to problem of that days. At
the other hand cassette tape recorders and tapes had already become very common in that days and had been availiable at an affordable price.

The cassette interface was sold on those days slightly below $80.- and due to the low prive the design had to be as simple and cheap as possible.
The circuitplan below uncovers that 3 logic chips and 1 opamp the most work was performed by the software left in 2 ROM-chips organized in the
order like on the mainboard as upper half byte and lower half byte adding up together to the entire byte. The advertisement displays the low price
of the interface card.

The Operation manual of the ACI is rather simple and short. It consisted of only 2 sheets of folded paper and wrapped down to half letter size.

Please also recognize the red marked area in page 4 ! the remark remind the user that at the mainboard a jumper must be added at the adressing-selection area ( in the canter at the 74154 )
to ensure correct operation of the cassette interface.

   In the meantime the Software routines of the Apple-1 Cassette Interface has been disassembled by members at Applefritter.com and here is just the overview
   of that disassembly:

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