#1
|
|||
|
|||
I can't get the Monitor to start...
I got an Altair 680 kit for Christmas from my wife (and Martin). I was very surprised!
However, it was missing all of the sockets, the power cord, fuse holder, back power switch, and most of the parts required to wire up the RS-232 interface. Sadly, I couldn't build it on Christmas day (DigiKey was closed) - Darn. So, after extravagant overnight shipping, and many hours of meticulous kit building, I was ready to power the 680 up. LEDs blink, memory can be accessed, read, and written, the power supplies are proper, but I get no "." on the RS-232. The computer is jumpered for 9600 baud, 8, n, 1, terminal, RS-232. The DB25 output (pin-3) shows -12, the input (pin-2) reads close to zero, and ground is ground (pin-7). I connected the DB25 of the Altair 680 to a DB9 for my laptop as so... DB25 pin 2 - 3 of DB9 3 - 2 7 - 5 I've used several different terminal programs with 3 different laptops, and still no monitor prompt. I'm running with only the 6800 and the ACIA Prom (the memory expansion board and VTL roms have been removed). I have not probed around with a scope yet - was hoping not to. I took the 6850 chip out and jumpered pins 2 and 6 together and I was able to get the laptop to see it's own characters (a loopback through the RS-232 circuit). So I feel confident that the wiring is correct. A logic probes reveals nothing on the output of the 6850 (pin-6). Any ideas? When the 680 in set to RUN, the upper LEDs (A9-A15) appear to be counting up in binary fashion. In fact, with the ACIA MON rom removed, the A13-A15 LEDs appear to count (I guess it's just random code). Did everybody else's 680 work okay? What else can I check? Thanks, Flash Last edited by FlashCorliss; 01-05-2009 at 07:53 PM. |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Kenbak-1 demo program. | Geoff Harrison | Kenbak-1 | 9 | 10-13-2007 11:42 PM |
address for disk boot rom / startup | lovenewyawkcity | Altair 8800 | 1 | 01-04-2007 06:24 AM |