IMSAI (moving along...)

From: Bill Sudbrink <bill_at_chipware.com>
Date: Wed Jul 7 16:13:27 1999

So I've identified and corrected one problem
with the front panel and now the address lights
and switches seem to respond correctly to EXAMINE,
EXAMINE NEXT and DEPOSIT NEXT.

For those who might be curious...

U15 (74ls04) had apparently been replaced several
times. In particular, the area around the pad for
pin 11 was rather charred. There seemed to be some
conductivity between pin 11 and one of its neighbors.
I desoldered U15 and soldered in a socket. Then cut
the trace about 1/8" from pin 11, reinserted U15
with pin 11 bent out and "air wired" pin 11 to a
convenient hole-through a little further down the
trace. Much better!

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
put in the INDUSTRIAL MICRO SYSTEMS 8K MEMORY BD.
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).

By the way... on the front panel, when powered up, the
PROGRAMMED OUTPUT lights are all on. Is this correct?

Thanks,
Bill
Received on Wed Jul 07 1999 - 16:13:27 BST