From: Ullrich von Bassewitz (uz_at_musoftware.de)
Date: 2002-07-07 23:49:43
Hi!
On Sun, Jul 07, 2002 at 09:31:28AM -0700, Cameron Kaiser wrote:
> That's because I'm not very clear about it either :-) We sat down with your
> picture of the 600 series board and Steve Gray's picture of his B500 and
> compared them and the boards are nearly identical, as you say. The only thing
> weird on my unit is that 5-pin video port. That's the only thing that seems
> to distinguish this as a 500 at all.
Well then here's the bad news: All of my 600s have a 5-pin video port :-)
> This is one major reason I'd like to restore this unit to at least see what
> the differences are. The board crystal says 1.843200 and the oscillator
> crystal says 18.000. How is this compared with the 600 and P500?
The 1.8432MHz crystal is the clock for the 6551 UART. It is very common. The
CBM 600 and 700 both use a 18MHz crystal as base for the 2MHz CPU clock. It is
divided by 9 by a shift register.
> Larry, since you asked about solder pads for the joystick port, I didn't
> see anything obvious rear left. It is completely dissimilar to the layout
> of the P500 Steve Gray has. Looking at his picture of the B500 and P500
> side by side, this is clearly a B-series board. It would seem logical to
> assume this is a 600, but the 5-pin video port is a 500 feature.
See above. I don't think that the 5-pin video port is special for the B500.
> However, I do have a connector "P1" where the joyports should be. Does this
> connect up to your joyports on the P500? On this board, it's top left.
The P500 has the joystick at the same location. The lower of both 9-pin DSUB
sockets is soldered in place, while the upper one is connected via a cabel to
the motherboard.
Regards
Uz
--
Ullrich von Bassewitz uz@musoftware.de
Message was sent through the cbm-hackers mailing list
Archive generated by hypermail 2.1.4.