Apple 1 memory

From: Bryan Blackburn <oldcomp_at_cox.net>
Date: Sun Feb 23 00:56:00 2003

Thanks Eric,

I'll take your word for it since I haven't looked at an Apple 1
schematic for about twenty-five years! That may have been another reason
I didn't put video on my board!

Bryan

Eric Smith wrote:

>Your Apple 1 homebrew page is interesting, but the details about
>Woz's design aren't quite correct. The Apple 1 did use 4K multiplexed
>address DRAMs (typ. MK4096) for the main memory. But the video memory
>was entirely separate, and consisted of seven Signetics 2504 1Kbit
>dynamic shift registers and a Signetics 2519 hex 40-bit shift register.
>The video memory recirculated constantly, so it didn't need any explicit
>refresh circuitry.
>
>It wasn't until the Apple 2 design that Woz shared the main memory with
>the display to get automatic DRAM refresh.
>
>Best regards,
>Eric Smith
Received on Sun Feb 23 2003 - 00:56:00 GMT

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