TRS-80 Model 4 help requested

From: Al Hartman <>
Date: Wed Feb 26 21:23:00 2003

From: "Fred Cisin (XenoSoft)" <>

> A minor complication with using DS drives, at least
> as external, . . .
> Didn't Radio Shack used pin 32 for drive select 3?
> Isn't that "side select"?

Yes, they did. I don't remember for sure, but I think
that on a Model I, you could only use 3 drives if you
decided to use Double Sided Drives.

On a Model III/4, it didn't matter as you could use
two internal and two external double sided drives
without problems (I think...).

It's been a while, and my memory is fuzzy on this one.

I used to use one DS/DD 40tk as Drive 0:, and two
DS/DD 80tk drives as 1 and 2 on my Model I when it ran
my BBS.

I had an LNDoubler in it, and always meant to get 8"
drives to get 1.2mb each instead of 720k.

I never did do that.

Now, I could put 1.2mb drives on with that, I guess.

You could boot from any size media that the controller
would support, you'd just have to make a boot floppy
on the correct media, as the drive settings were
contained in the boot sector of the disk.

On a Model I, the boot sector ALWAYS had to be Single
Density, no matter what the rest of the disk was.

That was the main difference between the Model I and
III. While they both had DD capability (the Model I
equipped with a Doubler), the Model III required a
Double Density Boot Sector.

I think that one of Dos'es (MultiDOS I think) would
boot on both machines as long as the Boot sector was
the correct type. I know one of the Dos'es could do

I REALLY have to find my dream machine... A complete
LNW Model I or Model II (Team) computer...

Al Hartman
Received on Wed Feb 26 2003 - 21:23:00 GMT

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