8 Oct
1999
8 Oct
'99
7:23 a.m.
The Challenger iii saga continues...
Yep, one of the 470's does indeed have a line of pins where a
daughter card
might have plugged in. Will the 510's rom let me go without a
daughter&disk
attached? If not, is a new one buildable?
Should be fairly easy to find. I may have a spare, but you
would have to trade me something good... It could also be built.
The 510 ROMs are just the bootstrap and a very crude monitor.
It should come up with some variant on the classic:
D/C/W/M?
prompt, you may have to hit the reset button a few times.
Most probably, it will prompt:
H/D/M?
Press 'M'. Note! The 'M' must be UPPER CASE or the machine will
ignore you. This will take you into the monitor. Once again,
I don't have the reference I need, try different upper case letters
followed by four digit hex addresses. PXXXX if I remember correctly
will dump memory starting at address XXXX. If you get this far,
the machine is in pretty good shape.
The 510 is wired out to a 5-pin female din mounted on
the back of
the OSI's
case. Tell me this is its serial port, and also tell me the pin outs. ;)
Well, let's see where it is attached. There should be a 4pin and
a 12pin molex connector on the top of the card, next to the corner,
away from the bus. The 4 pin connector is the manual processor select,
nothing should be attached there. The 12pin connector is where the
serial port and reset switch should be attached. Pinouts:
(Pin 1 is away from the bus)
1 -- NC
2 -- Ground (for use with reset)
3 -- Reset
4 -- NC
5 -- NC
6 -- Ground
7 -- RS-232 OUT
8 -- RS-232 IN
9 -- 20mA OUT current (probably not populated)
10 -- 20mA IN current (probably not populated)
11 -- AUX OUT (probably not populated)
12 -- -9 volts through a 470ohm resistor (probably not populated)
If it is set up for 20mA current loop, then I'm not sure I can help
you. My schematics don't seem to be complete for those mods.
The port was factory wired for 2400 baud, no parity, 8 data bits, 2 stop
bits. Only thing likely to change is the baud. Possible values are: 75,
110, 150, 300, 600, 1200, 2400, 4800, 9600 and 19.2K. If it has been
changed, there will be pins soldered to the board, below the connector
and the 6850 USART beneith it. Two or three of the pins will be
wire-wrapped
together, connecting the Rx an Tx clock inputs to a clock source. It is
possible, although I can't imagine why, that the Tx and Rx clocks could
be set to different rates, in which case two pairs of two pins will be
connected.
And... any idea how many of these were sold? This one
seems to have a
pretty low serial number...
Not a clue. If it has a metal serial number plate then it is much
newer (post-1978?) than if it has a paper serial number sticker.