23 Apr
2020
23 Apr
'20
5:51 p.m.
Oh I'm using an MTI MQD13 card as my disk controller. It is a MCSP
controller that can interface up to 4 ESDI drives to Q Bus. Pretty fast.
Just checked the configuration and block mode DMA *is* off. Wonder what
happens if I turn it on...
It does have a lot of knobs to fiddle with, so maybe I can figure out
what works and what does not for these memory boards. Experimentation!
C
DMA CHARACTERISTICS: DRIVE 2... ESDI
BLOCKMODE............ OFF FIRST LOGICAL...... 002
BURST LENGTH (WORDS). 16 SECOND LOGICAL..... 006
THROTTLE............. ON DRIVE 3... ESDI
DWELL us............. 1.6 FIRST LOGICAL...... 003
SECOND LOGICAL..... 007
SEEK MODE................ OVERLAPPED
SEEK OPTIMIZATION.... ELEVATOR COMMAND QUEUE.......... 008
FAIRNESS VALUE....... 016
On 4/23/2020 1:17 AM, Mark Matlock via cctech wrote:
Date: Tue, 21
Apr 2020 16:17:07 -0400
From: Chris Zach<cz at alembic.crystel.com>
To:cctalk at classiccmp.org
Subject: Re: pdp11/84 PMI memory: What is the problem with Q bus?
Message-ID:<27647f0e-19d4-b484-d288-e9f3bb715363 at alembic.crystel.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Thanks Mark! Actually this was just the boards from the 11/84 (no idea
what happened to the chassis, drat) so it's an 11/84 CPU (18mhz, FPP
chip installed), 2 PMI boards (one old 2mb, one new 1mb) a console board
of some sort and the Unibus map.
I popped this into my BA23 to speed things up a bit in place of my quad
height 11/73 CPU with 2mb memory. So far it seems to work, and with the
CA memory in the PMI slot managed to boot RSX11M 4.2 and compile up EMPIRE.
Chris,
I understand now. I also have a PDP-11/83 in a BA123 box and the CPU and
PMI memory (M8637-E) can move from the Qbus box to the 11/84 box and work fine
In either. I spent a good bit of time tinkering with the 11/84 power supply which did
not
Work until I put a M7556 minimum load module in it. Basically the ? 12 Volts needs a
Load or you get a hung bus error. Also, with the Unibus you have to pay attention to
The NPR/NPG grant jumpers.
For disks on the QBus systems I used the UC07 and SCSI2SD. The UC07 can be
can be configured for block mode transfers and I think it is doing it. I guess I?d
need
to hook up a logic analyzer to know for sure.
The 11/84 uses a UniBone and when it is emulating a MSCP disk, it can do 150
I/Os a second (using IOX on RSX11M+) The 11/83 using the UC07 and a SCSI2SD
Does about 60 I/Os per second. I think the UC07 could go faster but is limited by the
SDcard interface. I need to put a fast real SCSI disk on it sometime and see what it can
do.