Data Systems Design DSD-880 8" floppy and Hard Drive

From: <(>
Date: Wed Aug 20 15:02:00 2003

I was going to do this offline, but I have had a couple of requests for
this info, so I will put it out to the list. I do not have the manuals
scanned, so I will excerpt from them. If any of you reading this have
one of the systems (or part of) that ends in an 8, meaning an 8 MB drive,
I would especially like to hear from you in order to try to see if it is
the electronics or the actual drive that I have that is bad. I have 3
working 30 MB systems, and I think I will be getting rid of them soon, as
I have moved the software over to a PC.

Here goes the explanation on the DSD 880 series from my perspective.
Data Systems Design (Qualogy) made two disk subsystems for Digital Equipment
Corporation (DEC) computers. It is possible they made other models, and
other adapters for Prime or DG, but I don't know anything about them.
The subsystems were external, in a 19 inch wide case, about 24 inches deep,
and about 6 inches high. They used a ribbon cable, 26 pin to connect to
the backplane adapter. The adapter had diagnostics upon bootstrap and
a bootstrap prom on it. The models were DSD 880xnn, where the X was either
an S or a D, meaning a single sided 8" floppy drive or a double sided 8"
floppy drive. The nn was either 8 or 20 or 30 for the megabytes. The
floppy emulated an RX02 or the double sided emulated an RX03 with a patch
to the OS. The winchester emulated an RL01 (8 MB with some waste), a short
RL02 (10MB) with a couple of megabytes of bad blocks, or 2 or 3 RL02s with
a patch to the OS for 3 RL02's. I am also doing this mostly in context of
RT-11. The manuals I have are dated 1982 and 1984, so that gives you some
idea of the age.

The bootstrap will boot either the floppy or the hard drive. There were
two different formatter/controller cards, models 8840 and 8841. There were
a few different adapter/interface cards, 8832 and 8836 for q-bus and 8830
for unibus. The winchesters had head and spindle locks located in access
doors underneath, for shipping. There was a modification to the 8836 to
support 22 bit addressing. The 8832/8836 are dual wide boards, while the
8830 is a quad board. The configuration of the 8832 and 8836 are in two
jumper blocks at location F4 and D3 on the card. These control the location
of the RL CSR, the boot address/enable, the floppy CSR, dma burst length,
the RL and floppy vector addresses and the priority levels. The unibus
version has similar features in 5 locations. The units shipped with a
diagnostic floppy that had a diagnostic monitor, a floppy and winchester
exerciser, a diagnostic program for the winchester in RL emulation and
a scan program for bad blocks.

The hyperdiagnostics panel is similar between the 8 and 20/30 drives,
except the mode 0 stuff is different. I will start with mode 1 stuff,
where the panel has mode and class (left,right)

Mode 1: floppy disk format stuff
class 0 format double density
class 1 format single density
class 2 set media to double density
class 3 set media to single density
class 4 set media double density and scan
class 5 set media single density and scan

Mode 2: system tests
class 0 floppy disk exerciser and write
class 1 ditto, but no write
class 2 fixed disk exerciser
class 3 floppy/fixed disk exerciser, write floppy
class 4 single pass of class 3
class 5 single pass of class 3 without write
class 6 floppy/fixed disk exerciser, no fixed/floppy write
class 7 fixed disk write enable, use this before fixed write tests

Mode 3: more hardware tests
class 0 controller switch and indicator test
class 1 general controller tests, alu,mem, crc, pll
class 2 alu and serdes test
class 3 memory test
class 4 crc test
class 5 pll test
class 6 display microcode version

mode 4: floppy disk alignment stuff.
        pretty specific, must have sa800/sa850 floppy maint manual

mode 5: read/write tests

class 0 single pass sequential scan floppy
class 1 butterfly seek floppy
class 2 butterfly read floppy headers
class 3 sequential write/read floppy
class 4 sequential scan hard drive
class 5 butterfly seek hard drive
class 6 sequential write/read hard drive
class 7 fixed disk write enable ( do before 6)

Mode 6 and 7 are for offline backup and restore, except 7 - 7
which is to set the floppy-type flag on the winchester bat track map
to tell the system if it is a single or double sided floppy, or no floppy.

Finally there are 40 or so error codes that can pop up in the diagnostic

Hope this satisfies some of the curiosity.

Joe Heck
Received on Wed Aug 20 2003 - 15:02:00 BST

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