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Last
but not least i intended from the very beginning to also develop
a RAMexpansioncard for the Apple-1 with as free as possible
configuring options. there have been already some contributions
published that described how owners of the original Apple-1
manipulated their mainboards to be populated with 4116 chips and
then those boards had 20 kB RAM. in fact there are
different variations of possible RAMconfigurations and therefor
it is upmost importent to also keep this card as variable as
possible by offering wide range of adressing and allocating the
different RAMbanks and offering to use different kinds of
RAMchip population. The Mainboard offers either 4kB of
RAMpopulation, 8kB or 20 kB. Depending to the availiable RAM on
mainboard the expansion card should offer either 4 kB, 8 kB, 16
kB, 20 kB or 32 kB additional RAM and it should be possible to
create entirely consistent RAMspace in one large block together. The trouble started while examining the slot and the availiable signals at the slot. I discovered that a lot of requested signals for RAMtiming and RAMrefresh are not availiable at the slot and that signals needed to make that signals are not availiable too. From that moment i recognized that the development of a RAMexpansioncard would become a very tricky and difficult task. Its one thing to generate tha requested signals for refresh and row and column adressing on the one side and its a complete other story to get that signals syncronized with the signals like the databus and adressbus as well as the CPU on the other side. |
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due to european laws
and german court decision: I hereby declare no responsibility to any "deep links" resulting from the links in this page. I have no influence to the pages linked hereby in this page and the contents in those pages. I therefor canīt take any kind of responsibility to contents in the pages, where these links direct the readers browser to nor to the contents resulting from following up links from those pages. The reference to contents by this links is dependent ro the status of the date when the links have been set ( April 2013 ) and it might occur that references and contents may change by the fact that domains may have been discontinued from their former owners. In such cases i canīt take any kind of responsibility to the changed contents. this is specialy valid to banners, advertisements or merchandising links in the targeted pages.
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