Re: Dynamic RAM / memory expansion

From: Ruud Baltissen (
Date: 2001-01-19 08:05:06

Hallo David,

Thanks for answering.

> Refreshing most 256k chips/simms, by the way, is exteremely simple.  All
> you have to do is flash CAS (or Ras? cant remembr) alone, and it'll
> refresh the correct row, and update the counter accordingly (one that's
> INCIDE the ram)

RAS has to be activated for CAS. See: This document (and
others) mentions self-refreshing DRAMS, ie the ones with in-build counters.
But then, how do I know which DRAM has (or not)?

Another problem is the 72 pin SIMM. It has a 32 bit wide bus. Nice if you
have a 486. But the 65xx is 8 bits wide. Is it possible to select just 8
bits? If not, 24 bits are waisted unless one knows a way to preserve the
data during a write-action.

Groetjes, Ruud

This message was sent through the cbm-hackers mailing list.
To unsubscribe: echo unsubscribe | mail

Archive generated by hypermail 2.1.1.