loading [Altus Metrum](https://altusmetrum.org) and other products that make
heavy use of 0402 passive components, and fine-pitch integrated circuits.
+## Challenges
+
+* The existing control computer will be replaced with a PC-compatible system
+ running [Debian GNU/Linux](https://debian.org) and
+ [OpenPnP](https://openpnp.org).
+
+* It appears that the stock board for doing things like sensing axis limits,
+ operating pneumatic actuators, etc, is actually attached to the control
+ computer using SCSI-1, and is based on an Intel 8031 with external EPROM.
+ Bdale hopes to reverse-engineer the protocol in use over this bus and use
+ a simple SCSI-1 interface on the control computer to interface with this
+ working board, so that it doesn't need to be replaced. This would also
+ allow us to leave almost all of the system wiring harness, all of which
+ is working, in place.
+
+* The existing analog servo amplifiers are fairly tightly coupled to the
+ control computer's electronics. Since the CSM84 came with some DC servo
+ control modules that take step and direction inputs and thus look can make
+ the axis servos look like stepper motors to the rest of the system, we're
+ going to try using a Smoothieboard and these modules to run the axis servos
+ using the existing power supplies.
+
+* The axis limit sensors currently feed into the main system I/O board, but
+ we'd like the Smoothieboard to be able to read them. This may require a
+ custom interface to extract those signals and feed them to the Smoothieboard
+ at appropriate interface voltages.
+
+* The existing vision system will be completely replaced by USB camera modules
+ attached to the new control computer.
+
+* The head-mounted vacuum sensor board will be replaced with something better
+ suited to OpenPnP's needs.
+
+* The reel feeders provided with the machine advance 8mm tapes by 4mm per
+ step, which is correct for parts that are of 0603 geometry and larger.
+ To feed 0402 parts, we either need to modify these feeders for a 2mm
+ advance, replace them with feeders that do 2mm advance per step, or just
+ throw away every other part on our 0402 reels.
+
## Sub-Projects
* The stock machine has a nozzle vacuum sensing board that uses an analog