Data General MTB Reference Sought

Stephen Merrony steve at
Thu Feb 23 01:32:51 CST 2017

Hi Bruce,

Thanks for that confirmation of my hazy memory!

What I can't seem to find is any reference as to how the tape drives interact with the DCH bus and the associated map slots.  I thought maybe a later guide might cover that?


-----Original Message-----
From: Bruce Ray [mailto:Bruce at] 
Sent: 25 January 2017 18:23
To: General Discussion: On-Topic Posts <cctech at>
Subject: Re: Data General MTB Reference Sought

G'day Steve -

AOS/VS OS tape drive base names are MTA, MTB, MTC, etc. and do not directly correspond to the assembler mnemonic name(s) - don't be confused by this difference.

The AOS/VS 'MTA'-type tape drive is described on page IV-5.  These correspond to the original DG model 4030/6020 units.

The AOS/VS 'MTB'-type tape drive is described on page IV-15. These correspond to the DG model 6026 units.

The AOS/VS 'MTC'-type tape drive is internally the same as the MTB except only a single unit is supported.  This was done to distinguish single-unit support for the popular DG model 6125 streamer.

The IV-15 mag tape programming model was consistent between the Nova/Eclipse/MV bus controllers and the Lbus controllers through emulation.  One size [almost] fit all.

What difference(s) are you seeing?


On 1/25/2017 1:01 AM, Stephen Merrony wrote:
> Does anyone have (a scan of) a manual that covers programming the 
> MV-era MTB tape controller?
> I have a 1980 "Peripherals" manual (014-000632-01) from the 
> "Programmer's Reference Series" which covers the MTA type, but it 
> seems that the MTB behaves a bit differently and I am missing some 
> information for my current project.
> Thanks,
> Steve

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