Well that's encouraging. Unfortunately, I don't have a memory expansion board, so I'm not going to be much help there. Maybe Grant will have some suggestions when he logs in.

Geoff.

The board works by installing the cpu into its socket. Then the mini board has through connectors on the bottom that plug into the original cpu socket on the motherboard. If I am reading the info correctly, I have identified that pin 34 does not make the connection through the socket into the motherboard by using my meter. This would be easy to fix. Of course I need to confirm that this isn't by design. I'm reading the schematics to try and determine. I'm sure Grant will be able to confirm.

Ah yes, that would be a Bad Thing. That's the Read/Write line from the CPU. I don't see anything on the circuit diagram that's not meant to pass through to the motherboard.

Geoff.

All that effort and I'm almost embarrased to say what the solution was. The socket into the motherboard from the mini 32k wasn't seated enough. The trouble is that you can't see the pins make contact very well because there is almost no clearance (Grant says this in the instructions). But, I had to use way more force to get a good seating than I'm usually comfortable with. Advice to anyone else, install the mini-expansion with the motherboard on a flat surface outside of the case.

What do they say? The obvious answer is usually the correct one?

The front panel and the terminal seem to be working perfectly.

Thanks Geoff, you led me in the direction of the CPU, which was the correct focus area.

Great. And congratulations on getting it running. It's a fun little machine, isn't it?

Geoff.

Yes, its been awsome learning how to make it work through the front panel. I've built other kits before, but this gives me the vintage feeling better than anything else I have done.

I really want to easily retain the ability to enter and execute programs through the front panel only. I was thinking of installing a small toggle switch on the back plate to allow the switching of no terminal - terminal setting. From what I'm reading, it is necessary to have that set correctly to execute a program from the front panel because it then knows to start execution at 0000 as opposed to the monitor.

Do you concur with this? Is there another way to get the same result?

I like the front panel too, but it doesn't really have the functionality to do anything useful. It is missing the examine_next, deposit_next, and start_at_address functions that are pretty much essential, and are available in the PROM monitor. It's handy to have a front panel to debug the hardware when things aren't working, and in that sense the 680 front panel is more useful than the one on the 8800, which requires a functioning CPU to do anything.

Geoff.

Thanks for helping so much Geoff.

The R/W line does not go directly from the 6800 to the motherboard. The GAL decodes the address. If the 6800 wants to READ from the flash or sram, then it puts the external Altair 680 bus in a WRITE mode. If it was in a read mode, then the data buffers from the expansion card memory and the 680 motherboard buffers would clash! :(

I know that isn't the cause of the problem here, I just wanted to explain it...

Have you used basic? Or VTL-2?

I have never used the assembler / editor yet. I use a software assembler on a Windows computer and upload the paper tape image file.

The memory upgrade board is a pretty nice spoiler... A few seconds to boot basic vs 13 minutes with an audio cassette player. :) Have you tried your upgrade board out yet with the updated flash monitor? I tested every single upgrade board by booting and loading basic.

I havn't played with VTL-2 yet, but I'm looking forward to it. I have used the new flash monitor and loaded basic. The convience is nice. Now I get to finish assembling the back panel tonight. I didn't want to button everything up until I was sure everything was OK.