anyone here ever make a X1541 cable?

[JDT]

Why not hook your PC up to a 1541?

Some ideas here.

I made this cable: http://sta.c64.org/x1541.html

to this specification:

http://sta.c64.org/x1541c.html

I've tested my cable with my multimeter... perfect, unless that specification leaves anything out?
I've tried to older PCs with the LPT port in PS/2 mode as requirements state.
Any ideas? was there anything left out of the schematics?
I notice nothing on PIN 1 of the DIN and the shielding doesnt connect to any ground or anything?

Thanks in advance.

 

[carlsson]

Yes, the specification should be correct. The X1541 cable only works with true SPP mode, so the question is what "older PC" are you using? The X1541 cable without diodes usually only works with 486 and older. For improved function, I suggest you source four suitable diodes, BAT85, 1N5819 etc and convert the cable to XE1541 or XM1541 while you're onto it. Those tend to be more compatible and can be used with a majority of modern PC's still having parallel ports. I've used my home made XM1541 cable with up to Athlon64 systems without problems.

 

[Chuck(G)]

Yes, by all means. The X1541 does some pretty ugly things, electrically speaking (such as driving/forcing outputs). While this was okay with LSTTL bipolar outputs, it's pretty bad with CMOS. Either the XE or XM cables are light-years better from a design standpoint.

Actually, just about any small-signal Schottky diode will work where specified--and you might even get some bog-common small-signal diodes, such as 1N914 to do the job well enough.

 

[carlsson]

The debate which Schottky diodes will work and which won't was a hot topic in the late 1990's and early 2000's. I think there is a big amount of YMMV there, a little depending on which chipset the PC side is using. I found some decent priced diodes that were not on the "certified" list but had similar specs. However I never get around to buy and try those. I think Wolfgang Moser (?) would have a lot to say in this topic. Fortunately the 2-3 known good types of diodes are rather inexpensive and easy to come by so it is not an adventure to source the right parts.

This is a table I assembled five years ago, but since I don't quite know what the values mean or if there is more to it than those values, I can't say if any diodes would be good substitutes in case someone has a box of spares.

|           VRRM IF    VF@IF IR@VRRM TRR
| BAT85     30V  0.2A  0.40V  10mA   2µA      <- OK
| BAT86     50V  0.2A  0.38V  1mA    5µA 4 ns
| BYV10-30  30V  1.0A  0.55V  1A     1mA
| 1N5818    30V  1.0A  0.55V  1A     1mA
| 1N5819    40V  1.0A  0.60V  1A     1mA      <- OK
| 1N5821    30V  3.0A  0.50V  3A     2mA
| 1N5822    40V  3.0A  0.53V  3A     2mA
| 11DQ03    30V  1.1A  0.55V  1A     1mA
| 11DQ04    40V  1.1A  0.55V  1A     1mA

 

[dabone]

Why not hook your PC up to a 1541?

Just a hint, before ordering stuff and spending any more money on this, do think about a zoom floppy. It just works, no old pc, no dos to mess with, I'm using mine with a core2 machine running Windows 7 64bit. I now keep a 1571 on top of my pc just to write out floppies.

They are only 35+shipping.

Later,
dabone