[net.micro.atari8] Help on adding I/O chips

DELAHAYZ@HLERUL5.BITNET (04/18/86)

Dear everybody,
I am thinking about adding some I/O ports to my 800XL(like the joystick ports).
I want to use them for my model-railroad.
The only problem is that I don't know which addresses are really unused(no
memory and no other chips) so that I can put them there.
Is there anybody around who knows those free addresses?
Thanks,
                Frits.
Frits Kuijlman
University of Leiden
The Netherlands
(Please,don't use the address above,I only use it to send mail to ARPANET,
 instead,use the following address.)
BITNET: WARNAAR@HLERUL5
ARPANET: WARNAAR%HLERUL5.BITNET@WISCVM.WISC.EDU

jhs@MITRE-BEDFORD.ARPA (05/27/86)

A friend of a friend designed a multi-function I/O board for the 800XL
recently.  Looking at the schematic diagram of the address decoding section,
it looks as though the region around $D100 - D1FF is probably pretty safe.
He decodes this whole block as though he plans to be able to use it for many
different devices.  I might be able to get more data on what he learned while
researching the project.

John Sangster
jhs@mitre-bedford.arpa