I am attempting to recover some files from a DECTAPE II cartridge.
They are in RT-11 format, so the most useful drive would be a TU-58.
Does anyone have a spare drive that they are willing to sell or at
least rent for a long time? The one that I prefer is a dual desk
top box with its own internal power supply and a 10 pin header on
the back for connection to an RS-232 channel so it can be connected
easily to a DLV11-J (or any other DL channel on a PDP-11 with some
wiring changes).
A TU-58 is …
[View More]normally standard with a PDP-11/44, so if the 11/44 is not
in a state to be rescued, that at least if there is a TU-58 available,
please contact me. They may also have been used with a VAX 11/780.
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On Feb 28, 16:04, Douglas Quebbeman wrote:
> Once upon a time....
>
> There were a bunch of these in the early hobby channel,
> say, around 1981... the seller had complete instructions
> for interfacing them, and included some rudimentary code
> for using overstrikes to simulate characters bot available
> in its 5-level (Murray?) coding scheme.
>
> They were going for $150 at the time, and I still could
> kick myself for not grabbing one, they looked pretty cool.
&…
[View More]gt;
> Anyone got a garage full of them?
Nope, my first printer was a 7B -- about 1981 -- but it's long since gone.
It cost me a lot less than $150! I'm sure I've mentioned before how I
wrote a driver for a Sorcerer for it, and how I changed the positions of
some of the type slugs to make overstrikes easier.
--
Pete Peter Turnbull
Network Manager
University of York
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any body know what the instuction set for the MZ3850 CPU is or better still
sourse code for the racal RA6790/gm or variant of that rx so i can change the
cpu for one that works.
On Feb 27, 22:48, Andreas Freiherr wrote:
> Also, the last three locations are slightly different, but this
> shouldn't present a problem:
>
> 2130 005000 CLR R0
> 2132 005007 CLR PC (my favourite PDP-11 instruction, really!)
> 2134 000000 HALT
I've seen one like that too.
> > sectors, not two. The reason for missing the even-numbered sectors is
> > because they are software interleaved to give time for the memory
transfers
> > between reads.
>
> …
[View More]I thought this is done by spacing the sectors on the disk surface (like
> 1, 13, 2, 14, etc.) and having drive electronics deal with the sector
> number from the preamble? Consequently, this would be a property of the
> floppy that would be implemented when the media was formatted.
RX02s are usually formatted with the physical sectors in strict order, so
software interleave is used.
> > Some versions actually have the HALT elsewhere. I once spent ages
trying
> > to work out the shortest variation on this bootstrap, IIRC I managed to
> > save just one word.
>
> I think more significant savings could perhaps be obtained by
> initializing a stack at the beginning and then using a subroutine like
>
> WAITRX: BIT R0, (R1)
> BEQ $-4
> BMI ABORT
> RTS PC
> ABORT: HALT
>
> to wait for any of the TR, ERR or DONE bits to come up, instead of
> repeating these instructions every time.
Possibly. But if you work it out completely, I think you'll find you save
very little. Not all of the tests are checking for an error, either.
> Since you never set the INTR ENB bit in the RX2CS register, you just
> need to keep your fingers crossed so no other device will issue an
> interrupt request... ;-)
Yes :-)
> Yes. But this is neither a typo nor a printing error. If you read four
> blocks of 200(8) _words_ each, starting at zero, you fill exactly
> 2000(8) _bytes_, and the next free location is 2000(8). As you state,
> the printed version is prepared for conversion to single density (by
> clearing the 400 bit in locations 2036 and 2072, right?) by reading in
> four blocks... - So, the reason is somewhat similar to that for the
> TS-11.
Yes, but if it's single density, which is the only reason you'd read four
sectors, the sectors are 128 bytes [100(8)] not 256, so it's still only
1000(8).
--
Pete Peter Turnbull
Network Manager
University of York
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On Feb 28, 0:16, Ethan Dicks wrote:
> --- Johnny Billquist <bqt(a)update.uu.se> wrote:
> > On Wed, 27 Feb 2002, Jochen Kunz wrote:
> > > On 2002.02.27 05:04 Gunther Schadow wrote:
> > >
> > > > I have the UDA50 manual
>
> Would that be EK-UDA50-UG-003? That's all I could turn up after
> pawing through stuff that isn't in storage.
> > I would really like to get my hands on the UDA50 programming manual. It
> > seems to be …
[View More]extremely rare.
>
> I'd say so.
I have two manuals that are relevant:
"MSCP Basic Disk Functions Manual
AA-L619A-TK Version 1.2
A part of UDA50 Programmer's
Doc. Kit
QP-905-GZ
First Edition
April 1982"
and
"Storage System Diagnostics
and Utility Protocol
AA-L620A-TK
A part of UDA50 Programmer's
Doc. Kit
QP905-GZ"
--
Pete Peter Turnbull
Network Manager
University of York
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> > > The Assign command works wonders in cases like these. Unfortunately
> > > MicroSoulth dropped it from their later versions of DOS. Still you can
> > > probaly use a copy from an older DOS and use other DOS cammand (that I
> > > can't think of the name of) to fake it into thinking that it's running
> > > under it's native DOS version.
> >
> > Could you be thinking of 'setver' (or was it called something else?)
>
> The MS-…
[View More]DOS ASSIGN command let you assign a drive letter for a drive, sort
> of like an alias.
>
> I think the syntax was:
>
> ASSIGN D: C:
>
> Meaning D: would be the equivalent of C:
Wow, sounds just like the DOS/CMD.EXE (NT, 2000) command called
SUBST
as in identical syntax...
-dq
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In the "useless trivia" category, DEC Rainbows all support 4 floppies (= 2
x RX50 drive) out of the box, though most came with only one RX50.
IMPDRV, by Warner Losh, will let you hook up a 3.5" drive in place of one
of those RX50's.
However, I know of no way to get "normal" 5.25" or 8" drives hung onto the
Rainbow, so I strongly suspect this is not of much use to you.
- Mark
The format depends on the program writing the tape, binary or text.
In "Binary" tapes, the eight holes correspond to a "byte", which is just loaded into memory, byte-by-byte.
The problem is that paper tape readers are error prone and any binary error was a potential crash.
To solve this problem, the Altair Basic "Boot" loader starts with a straight binary tape.
The straight binary formart continues for a few hundred bytes during which a "checksum loader" is read.
Then a special binary code on …
[View More]the tape triggers a jump from the "boot loader" to the "checksum loader".
You can recognize the blocks of the checksum loader on the tape, because every foot or two, you see a code that consistently repeats.
Text format paper tapes are almost always simple, standard ASCII codes translated into binary.
Text format can be recognized because, in those days, ASCII was almost always limited to 7-bits.
This means that the tape has a column on one edge with very few holes -- that is the column 8.
The other side is column 1.
Here is a link to an excellent 7-bit ASCII table that I just found:
http://www.neurophys.wisc.edu/www/comp/docs/ascii.html
Here is a clip from it:
Decimal Octal Hex Binary Value
065 101 041 01000001 A
066 102 042 01000010 B
067 103 043 01000011 C
068 104 044 01000100 D
069 105 045 01000101 E
So with column 8 on the left, you read like this:
(Holes in the tape translate to binary "1"s.)
xOxxxxxO translates to 01000001 binary -- which is the octal 101 -- which is a capital "A".
xOxxxOxO translates to 01000101 binary -- which is the octal 105 -- which is a capital "E".
Most of us found "Octal" codes easiest to work with manually -- Hex became popular later.
Got It ?
-----Original Message-----
From: Vintage Computer Festival [SMTP:vcf@vintage.org]
Sent: Thursday, February 28, 2002 5:51 AM
To: Classic Computers Mailing List
Subject: Need paper tape encoding format
Is there info somewhere that shows how symbols are encoded onto paper
tape?
Ideally it would include the actual hole positions like so:
8 4 2 1
A: *
B: *
C: * *
(Note: this is not an actual example but just an example of the format
I'm looking for. Of course.)
Thanks!
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
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> Robert F Schaefer wrote:
>
>Apparently the thought was to sell/bundle the 90 degree cable, to
force the
>purchaser to `upgrade' to the straight cable when it was necessry
to plug
>in more than one SCSI device. I cursed it soundly when I realized
it
>obstructed the pass-thru connector on the back of the TK50 I have.
As all
>my other SCSI toys have the HD connectors, I might have to end up
getting a
>50-pin centronics-like :) M-F cable to connect things.
…
[View More]Sometimes the 90-degree cable works best and sometimes
the straight one works best. The 90-degree ones work
nicely at the back of a VS4000 ... not so much
spce is needed at the back of the box (vents
are at the sides!).
Same deal goes with the 90-degree vs straight
ethernet connectors.
Horses for courses.
Antonio
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ASSIGN (with the format such as "assign a=c" -- no colons allowed)
"Instructs DOS to route disk I/O requests for one drive into disk I/O
requests for another drive" (IBM DOS 3.30 Ref Manual).
SUBST (with the format such as "subst g: c:\foo\bar") "Allows you to use a
different drive specifier to refer to another drive or path." It's useful
where a program does not recognize paths, but does recognize different drive
letters.
Bob
-----Original Message-----
From: Douglas Quebbeman [mailto:…
[View More]dhquebbeman@theestopinalgroup.com]
Sent: Thursday, February 28, 2002 1:27 PM
To: 'classiccmp(a)classiccmp.org'
Subject: RE: Multiple floppies in one system?
> > > The Assign command works wonders in cases like these. Unfortunately
> > > MicroSoulth dropped it from their later versions of DOS. Still you can
> > > probaly use a copy from an older DOS and use other DOS cammand (that I
> > > can't think of the name of) to fake it into thinking that it's running
> > > under it's native DOS version.
> >
> > Could you be thinking of 'setver' (or was it called something else?)
>
> The MS-DOS ASSIGN command let you assign a drive letter for a drive, sort
> of like an alias.
>
> I think the syntax was:
>
> ASSIGN D: C:
>
> Meaning D: would be the equivalent of C:
Wow, sounds just like the DOS/CMD.EXE (NT, 2000) command called
SUBST
as in identical syntax...
-dq
[View Less]
