1 Jan
2008
1 Jan
'08
3:18 a.m.
On Tue, Jan 01, 2008 at 03:37:44AM -0600, Jim Brain wrote:
Dan Gahlinger wrote:
>I'm looking for something very rare on the commodore 64 (c64 or 64c) line
>of computers,
>
>it was called "drive mirror" for the 1541 disk drives
>
>it was basically an LCD display built into the drive that showed the track
>and sector values.
LCD? I remember an LED track-only display.
>I read a magazine article (or online) once that
showed how to do the track
>and sector displays...
Any recollection where?
I'm assuming a T&S display would have to
intercept some RAM locations,
as the electronics do not have any idea of the T&S. address 0x22 holds
track, while 0x4d holds next sector to read (0x4c holds last sector
read). I'm assuming one would just wire up a 573 to each address, and
grab the data, converting it to decimal.
.
.
.
0x80 also states it is TRACK, with 0x81 being sector.
These may be the
bytes Drive Mirror was looking at, since they are so close together, it
would be relatively easy to decode them.
Sure... wouldn't even take a '688 or other large address decoder. An
8-input NAND or two with an additional gate for 0x80 vs 0x81 for the
latch input. Hex to 2-digit BCD might be a bit hairy in TTL, though.
Did the Drive Mirror use PALs/GALs or straight TTL?
I've got some Atmel AVR code here that could
possibly be persuaded to
"snoop" on the drive line and watch all the IEC commands, optionally
outputting them to an LCD.
I remember the ad for Drive Mirror, but I never have seen one.
Any idea how it mounted? Did you install flea clips? Solder on wires?
Plug into the CPU socket?
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 1-Jan-2008 at 11:10 Z
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Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html