Holy Crap! IMSAI's weren't this expensive when new!

From: Richard Erlacher <edick_at_idcomm.com>
Date: Sat Feb 10 12:39:35 2001

----- Original Message -----
From: "ajp166" <ajp166_at_bellatlantic.net>
To: <classiccmp_at_classiccmp.org>
Sent: Saturday, February 10, 2001 10:49 AM
Subject: Re: Holy Crap! IMSAI's weren't this expensive when new!

> From: Richard Erlacher <edick_at_idcomm.com>
> >Well, hopefully he recognizes what a DOG this system is,
> Since he knows the NS horizon and altair with MDS-A (mine back
> in the 70s) he may just have an appreciation for how good it was
> compared to it's contemporary peers.
> >with its NorthStar
> >controller. It will never have a decent-sized TPA thanks to the
> >memory-mapped controller, and it will never read soft sectored diskettes
> First your comments on the lack of TPA are unfounded and incorrect.
> Even with the poor implmentation of V1.4 (Lifeboat) the TPA was 52k
> and with the later V2.2 version 58k was easily done. For most CP/M apps
> of the time 48-56k was plenty.
I don't see how you can say that they're unfounded. Since the FDC sits at
0xE000 that puts an upper limit on the TPA. Memory mapping the FDC was,
from what I observed back when it was relevant, just about the most stupid,
Stupid, STUPID thing one using a Z80 could do. It helped nothing, save
perhaps some wiredosity of their equally silly choice to use hard-sectoring,
clearly designed to lock users into their scheme of things once they had
them, AND, considering when they came out with it, it prevented the average
user from utilizing the more popular software packages, which, because of
the timing, were too large to run in the small TPA. Remember, they wanted
their customers to run NDOS, not CP/M, and CP/M required a contiguous memory
span up to the BIOS. The BIOS itself, of course, could use memory ABOVE the
controller and EPROM if there was any. Of course, NorthStar didn't support
that solution. At the time, if you had an application that was coded in
MT+, which was VERY popular at the time, it required at least a 56K TPA.
Now, the TPA was the part of memory that lay BELOW the BDOS. If you load
something at 0100 and run it up to 0xE000, there's no room for BDOS or BIOS.
That's why, at that point in time, until later when the popular compilers
were rewritten to support overlays, machines like the NorthStar and some
from Vector Graphics, both of which were famous for their small TPA's, were
pretty much useless.
> As to reading soft sector, Irrelevant.
Well. not exactly. If you didn't mind that you couldn't use anything but
NorthStar-formatted media, you could survive, but there was no chance at all
of having any media interchange with anyone without a NorthStar controller.
I bought three NorthStar systems for $1 each and donated them to the Boy
Scout troop a friend of mine was running back in '80. The complaint with
which I got them was that there was no way to use them because the TPA was
too small and because you could not read standard media. Rememver, Allison,
the CP/M diskette standard, and there is only one, is 8" IBM 3740-formatted
SOFT sectored single-sided ...
> >either. Fortunately, he can probably afford to put up with the
> associated
> >problems.
> Irrelevent. He may also know that there is also very good support for
> ^ Have you ever considered using a spell-checker?
> that configuration, still.
really? Where?
> Allison
Received on Sat Feb 10 2001 - 12:39:35 GMT

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