In the very moment i decided to assemble a Apple-1
replication board and ordered a MIMEO, i also decided to
develop some kind of expansion to the replication board. In
fact the replica board has like the original Apple-1 only 1
slot and the is under normal conditions blocked by the ACI (
Apple cassette Interface ) and this canīt be avoided unless
you drop the opportunity to load or save your programs. At
the days when Woz designed the Apple-1 he didnīt think about
expanding the Apple-1 except adding a storage-option. But
even then some owner decided to use the 3 rows of pads on
top of the board to get more freedom.
Anyhow this meant direct changes to the mainboard itself with the related risks of damaging the mainboard itself. The Apple-1 was only quite a limited time sold in the market and Woz found by feedback of the users that this was a bad disadvantage and very soon he designed the Apple II as followup and of course removed disadvantage by adding 8 slots for maximum expandability. This lead to the large success story of the Apple II. But as result of the soon followup of the Apple II the Apple-1 owners have been left with their "single slot beast" and the advice "to buy an Apple II". Sound quite similar to the sentence issued from Apple, when the batteries of the iPod1 died - without replacement offer....
But the Apple-1 was such great invention, that - if enough time would have been given to the market - and if the introduction of the Apple II would have been delayed a little bit more - there would have surely been some third party guy - who would have developed those expansions, that are now given to the users. This expansions would have removed the lack of the disabilities and given the user the nearly same freedom, as it was granted to the Apple II community.
At the other hand i want to keep that expansioncards limited to the "state of the art" of the time when the Apple-1 was sold, so i only want to use chips that also have been availiable in those days and the design shall be limited to the resources of those days targeting to the aim of "authenticity" - so the users will not loose the authentic "Apple-1 feeling". Its just a step back to those days and assuming that the Apple II would not have happened that fast.....
In the first step the Apple-1 can be expanded by another 2 slots for additional expansioncards. While examining the edgeconnector i discovered that the +12 Volt and the -12 Volt at the edgeconnector are not stabilized but only the rectified powersource from the electrolytic capacitors is offered at the adgeconnector. The next point uncovered was the fact that the - 5 Volt are not availiable at all at the edgeconnector. Then in the following weeks after the first version of the slotexpansioncard had already been ordered from the PCB-manufacturer - i discovered that the +5 Volt branch at the slot is not very strong, because most of the power is used up at the mainboard itself. Therefor i decided to add also the ability to add up additional external powersouce and further stabilization of +5 Volt similar to the ability of connecting external powersource for the +12 Volt and - 12 Volt. The design left enough space to supply the voltage regulationchips with heatsinks if desired.
At the current moment the
different cards are designed for usage within the following
due to european laws
and german court decision:
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