hilpert at cs.ubc.ca
Thu Jan 7 16:08:52 CST 2016
On 2016-Jan-07, at 11:13 AM, nierveze wrote:
> first am 1 on the correct channel??
> I have several S100 boards , found 25 years ago,
> I wonder how it is possible to address more than 64K (rams+eprom)with a Z80 .
S100 memory boards often incorporated a bank-switching scheme to allow for multiple 64K banks in the system.
The convention was a dedicated I/O port number (0x40?) to which one writes a bit pattern to select the desired bank.
Such memory boards have configuration switches to set their bank ID/number.
For a system to use this scheme, all the memory boards in the system are to be listening on that same port, waiting to recognise their ID.
There's also the PHANTOM line on the bus, used to allow a bootstrap ROM to take precedence over some address space at reset/power-on, thus overlaying some RAM during boot. The ROM is switched out at some point to allow access to full RAM.
> I need documentation about it .
Best sourcess for S100 board docs are:
Seems to be a lot of duplication between the two, I'm not sure which site the (duplicate) material originated on (who's copying whom).
There's also this site, although I'm not as familiar with it:
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