APPLEBOX - the Apple-1 pages
 

 
    
 the Apple-1 expansioncards
 

   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.

 
 
 
possible Orders
up till now:        6

 

   A)   Apple-1 slotexpansioncard
( After revision and correction! )
   some minor corrections still possible...

   Important change : additional +5 Volt stabilisation and external powersupply added !
  this change will not be on my own testing boards - but it will be on the
  PCBīs ordered and at least one of them will be tested before shipping.
   see remarks at the right side ----------------->
  Reason: If RAMcard is completely populated and ROMcard inserted,  the remaining rest of power from the mainboard
   ( from the 3 Amperes on board only 0, 6 Amperes left ) may bear danger for the onboard powersupply.		  
 
 
      additional remarks:
The Apple 1 Slotexpansion
is designed with additional
stabilisation for the -12 Volt
and the + 12 Volt branch and
if desired to also add external
+5 Volt powersource and
stabilization.

In fact at the slotconnector is only the unregulated
voltage for these both 12 Volt branches availiable
and the card is designed for both options:

1. using the unregulated from the connector and
putting it to a regulation and then delivering it to the additional slots as regulated voltage

or:

2. not using the power from the connector but instead using two plugs and inserting there at each plug 12 Volt AC voltage and then getting after the reticifers DC voltage which is regulated and delivered to the aditional slots without producing load to the mainboard and itīs powersource.

In both cases there is enough space left to apply a heatsink to the regulatorchips.


 
 
 
   
 
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Đ copyright: Harro Walsh 2013