TU-58s (was Re: Some progress with my PDP-11/73 system)

[Allison]

>
>Subject: Re: TU-58s (was Re: Some progress with my PDP-11/73 system)
>   From: "Jerome H. Fine" <jhfinedp3k at compsys.to>
>   Date: Thu, 05 Apr 2007 16:35:21 -0400
>     To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
>
> >Allison wrote:
>
>>So happens one of my "small" pdp-11s uses a Tu58.  the system is a BA-11V
>>with an 11/23 256k of ram, DLV11J and MRV11 rom(boot).  Takes 10 minutes 
>>to boot, setup VM: then copy key files to and reboot. After that it's 
>>pretty decent even if I have to access a file on tape.  
>>
>>Everytime I runs it with a bunch of kids of the current PC generations 
>>they go gaga and comment on how slow then I explain the amount of ram and 
>>storage then they are amazed it can be a functional machine with so little.
>>They can't imagine a useful machine with 32kW of ram and 256kb of storage.
>>  
>>
>Jerome Fine replies:
>
>At some time or other, I saw a VT103 with dual TU-58
>drives in the bottom.  As noted, it took about the
>lunch break to boot.

Files in wrong order.  I learned how to make a pdt11/130 
boot faster and thats a LSI-11 no extra ram.

One trick was to put bad blocks at the end of each track
to fource files to be sequential without wraping around 
to the beginning.  Saved a lot of long rewind/seek operations.

>However, a VT103 can actually support a PDP-11/73
>with all 4 MBytes of memory if the backplane is
>upgraded to 22 bits.  The other 2 quad slots can
>have items like a TQK70, a DHQ11 and an RQD11-EC
>which allows up to 4 * EDSI hard drives.  In the
>case of ESDI hard drives, I  STRONGLY suggest
>used a separate power supply.  Otherwise, an
>RQDX3 with an RD51 can also be used and it is
>then possible to place the RD51 under the tube.

A RX180 (VT180) disk box with a floppy and a 
st225 and a VT103, a sweet system with a 11/23 or 
faster CPU and 4mb ram (run VM:!)

>At that point, you can play games with those PC
>generation of kids and tell that that you don't
>even need a computer, just a monitor and keyboard!
>
>If you use a dual PDP-11/73 or PDP-11/23 with a
>DLV11-J (and no boot ROMs on the CPU), then
>the SIGMA controllers are very handy, either
>a dual MFM (or ESDI) version or the quad ESDI
>version.  Again, with the dual MFM version,
>an RD51 (ST412) can be placed under the tube
>and use the internal power supply of the VT103.
>
>It must be about 20 years ago that I did this
>conversion of the RD51 hard drive under the
>tube.  I think I still have the backup VT103,
>but without any boards or a suitable controller.
>
>With any ESDI drives, limit the use of the internal
>power supply of the VT103 to a single drive for less
>than 10 seconds which would probably be enough to
>boot and copy any needed files to the VM: device.

Sounds nice.  I have a few BA-11VA (four dual width slots)
and it's a challange to put enough boards to make a bootable
viable  sytem in that.  An 11/23, 256k ram, DLV11J and a Rom
card was full house and for storage the only choice was TU58
or Tu58 emulation (requires bukly balky PC).  Though at one 
time Sparetime Gizmos offered a TU58 emulator in hardware 
using ram with battery backup (total of 512k or DD0/DD1).  
I have one of them and that is remarkably fast as there are 
no seek dealys and at 31k baud you can move enough to 
appear decently fast.

There was also a third party TU58 like system that also 
used serial and instead of a tape it was rx50 compatable 
floppy.  I'd love to find one or at least drawings and rom 
code.


Allison

>Sincerely yours,
>
>Jerome Fine
>--
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