IMSAI (moving along...)

From: James Willing <>
Date: Wed Jul 7 23:54:43 1999

At 05:13 PM 07/07/1999 -0400, you wrote:
>So now, on to the data lights. With no memory board
>installed, I get 0xFF (all 8 data lights on) for any
>address. This is correct behavior, is it not?


>I then
>Checking each 4K (0x0000, 0x1000, ..., 0xE000, 0xF000)
>I still get nothing but 0xFF. Try DEPOSITing 0x00 at
>each 4K, still nothing but 0xFF. On the board, J1 is
>jumpered at 0 (choices being 0-7). I assume that this
>is the bank number and that would make this board 8K
>starting at address 0. J2 is open (I have no idea what
>this means).

"Bank" may well be the key here. If this board is the same as most of the
Industrial Micro Boards that I've got in my collection, they are static
boards and should work just fine in an IMSAI, but there are two sets of
jumpers to set.

One sets the base memory address, and the other sets the 'Bank' number that
the board responds to. This was used in early 'bank switching' schemes to
extend memory beyond the 64k addressing limit.

There may also be a set of jumpers to set the I/O Address for the bank
control port, and to set if the board enables on power-up or not.

What all sets of jumpers does your boards have on it? If the layout is
similar, I can pull one of the boards (and or docs) down and probably give
you some more information.


The Computer Garage -
Computer Garage Fax - (503) 646-0174
Received on Wed Jul 07 1999 - 23:54:43 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:32:11 BST