In most tape devices the DCH Device address register refers to a logical
address - 0-32 KWords in Novas and Eclipses, and usually 0-256KB in most
MVs. In a mapped system, DCH map functions are transparent to these
devices since only the 'logical' address is sent from the device to the
CPU during a DCH data transfer. It is up to the specific processor and
its corresponding operating system to determine how and when the
logical-to-physical map. The DG hardware interface guide describes the
PIO, DCH and on MVs the BMC, specifications.
On 2/23/2017 12:32 AM, Stephen Merrony wrote:
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?
Steve
-----Original Message-----
From: Bruce Ray [mailto:[email protected]]
Sent: 25 January 2017 18:23
To: General Discussion: On-Topic Posts <[email protected]>
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?
Bruce
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
