A bit of a longer video today from RonTheCat's KC lab. Hopefully it has some interesting stuff you've not seen before, unless you are a BSR
We have converted Ron's Keyboard Component setup from a Blue Whale into a replica of a Mattel Black Whale development kit. We have a video of the result, hopefully it gives a flavour of what using some of Mattel's tools might have been like in 1983:
The video is done in one long take, so there are some errors and flubs along the way . I've added chapter points to the YouTube description, so you might want to view it there if you are after a particular section.
The big news is that this demonstration confirms the excellent re-engineering of Daniel Bass's development kit boards done by JoeZ and FrankP. Great work guys!
There are some things we probably should have mentioned, but forgot:
- Ron's KC is a standard production model (a Computer III). In converting it to a Black Whale it was not modified in any way.
- The MC used is a standard NTSC Intellivision model 1. In addition to the modifications mentioned as you can see we removed its RF shield for easy access.
- We don't know how Mattel modified the MC to link the PCIT and INTR pins to get breakpoints to work. The circuit used is a minimal solution constructed from first principles.
- The Dev Kit software is not completely compatible with Ron's KC. We had to change two bytes in the 6502 code to get it to correctly initialise the serial board. How this incompatibility was circumvented at Mattel is not known.
- We don't know what, if any, PDP-11 comms software was used by Mattel. We do know that there is no flow control between the PDP-11 and the Black Whale. So either can flood the other by sending data faster than they can process. With VTCOM in FAST mode this will sometimes happen at the end of sending a line of program data. We could use VTCOM SLOW mode, however, this is very conservative and takes an order of magnitude longer. So we use FAST mode and slow down the emulation while we download a program to prevent data corruption. Presumably this would not be necessary if we used a real PDP-11 and the comms software used by Mattel.
- Other than typing X to start the Dev Kit software you don't use the KC directly. All the commands are typed on the terminal (in this case a wireless keyboard connected to the laptop).
- We're not sure why our first attempt to set the value at $5C2A failed. Looking back, judging by the $F3 returned by the dev kit, it seems we might have changed the data in some other address. Thankfully it did not screw up the demo!
As always, many thanks to RonTheCat for an excellent lunch and for the chance to play with his many, wonderful Intellivision toys.
Links to things mentioned in the video:
- Development Kit Reverse Engineering Report by JoeZ
- SimH Minicomputer Emulators
- IMDI - the Intellivision Music Digital Interface
- Intellivision break out board and MC/KC extension cable
- Intellivision development tools description