TRS-80 "Eight Meg Disk System" questions...
dkelvey at hotmail.com
Thu Apr 12 09:25:31 CDT 2007
>From: Josh Dersch <derschjo at msu.edu>
>Hi all --
>Recently picked up a TRS-80 "Eight Meg Disk System" (model 26-4151) and the
>associated interface board, with the intent of hooking this up to my TRS-80
>On further investigation, it appears that the 26-4151 is a Secondary drive,
>which makes me curious as to whether this effort is going to be ultimately
>fruitless. So, without further ado, here's the questions I have:
>1. Is it possible to get this secondary drive working as a primary, or am I
>up a creek without having a primary drive (or extra magic hardware in the
>drive I have.)
>2. If I can work around #1, I need to know the pinouts of the drive and the
>controller board since I do not have a cable to connect the two. The
>controller has a 50-pin edge connector and the drive has three connectors
>-- 2 50-pin (labeled "Control") and one 20-pin (labeled "Data").
It sounds like you have a mismatch of things. It sounds like you have
the interface board for the 5 Meg drive and the 8 Meg drive that
has the controller in the trs-80. The 5 Meg came with the controller
in the drive board ( although, I've seen some indication that some
of the 8Meg drives did this as well ). The newer large drive had
the controller in the trs-80 box and required the two ribbon cables
of 50 and 20 pins.
It can be made to work with either a controller board from a 5 Meg
or a wd1001 board. Both have been on ebay resently but I only
see then every couple of months. Of course one can get the
controller board that mounts in the trs-80.
The wd1001 will require a little additional circuit to do address
The controller went for a 'buy it now' but was the second time it
Just to make sure, open up your drive box. If all that is in there
is a power supply and drive, then you'll most likely need to find one
of the controller boards. If it has a large board, then one of the 50
pin connectors was to be connected to the interface. You should
> a. And as a follow on to #2, where would you suggest getting the parts
>and tools necessary to build the aforementioned cable? I've never
>constructed such a cable, and I'll have need to do so again in the future
>(need to assemble some long-ish ESDI cables for my PDP 11/73...)
Although, I currently have a crimper tool for these connectors,
I've had good success with a vice and a couple strips of metal.
With either method, one can still mess them up. One needs
to make sure the ribbon is well aligned before the final squeeze.
>Thanks for any suggestions,
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