25 Oct
2007
25 Oct
'07
8:44 p.m.
Tony Duell wrote:
You still want to get a boot disk, so you cna use the
disk drives, etc.
Most PC controllers can write the TRS-80 format (you should use a 360K
drive in the PC, BTW, the TRS-80 uses 40 cylinder disks normally).
Got some DOS disk from TRS-80.com and the systems works fine.
That's very unusual. That sounds like the typical
behaviour of an SMPSU
that's detecting a problem and shutting down, but of course the M1 supply
is a linear one. This _is_ the origianl supply, right?
-tony
It's an original RS black brick, analog type power supply. I'll look
into this over the weekend.
Now, yet another problem.
On the IBM 5100 system I got, there is a problem with the keyboard. If
you press the shift key (either one)
or the command key, they act as if they are stuck down. Not
mechanically, but logically. I took the keyboard
apart, it's an interesting design. The key switches are a capacitive
type, but operate in the reverse of other
keyboards of that type I have seen before. All of the key switches are
pressed down in the "open" position.
When you press a key, the capacitive plate moves away from the pads on
the PCB.
I swapped key switches around and the problem stays with the shift and
cmd keys. After downloading the
maintenance manual from bitsavers.org, its clear that those keys control
latches that change the key codes.
There is a logic diagram, but not a real schematic. I believe the IC's
are all TTL type, they are all made by
TI or National, but all are IBM house numbered. Before I start to trace
out the logic, does anyone have
a cross reference for IBM IC numbers to industry standard numbers?
Anyone with a real schematic that
shows pin numbers on the IC's?
Thanks,
Bob