>
>Subject: What is DECdatasystem?
> From: "Wolfe, Julian " <ISC277 at CLCILLINOIS.EDU>
> Date: Tue, 25 Oct 2005 21:16:07 -0500
> To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk at classiccmp.org>
>
>Okay, looking over the web, I've seen several PDP11 machines marked
>"DECdatasystem"... They don't seem to have anything in common...it's like a
>random marking DEC decided to put on machines. Anyone know what it means?
The common thread of 'datasystem is they are bundled systems sold as
application solutions rather than "computers".
It's part of DEC's history that Digital didn't sell computers, they
sold programmed data processors. that and quirky marketing.
Allison
Ex Digit.
Okay, looking over the web, I've seen several PDP11 machines marked
"DECdatasystem"... They don't seem to have anything in common...it's like a
random marking DEC decided to put on machines. Anyone know what it means?
On Mon, 24 Oct 2005 05:00:57 +0100 (BST), ard at p850ug1.demon.co.uk
(Tony Duell) wrote:
>
>>> The 11/730, of course, is mostly PALs (as I said) with some RAM as a
>>> control store, 8 off 2901s as the ALU, and an 8085 (I think) to
>>> load the
>>> control store, etc. One day I am going to look into modifying the
>>> microcode of that machine...
>>>
>>
>> To what end? Increased performance?
>>
>
> NO, just for fun... I doubt very much I could improve on the
> performance
> for running the VAX instruction set. I have not looked at the prints
> carefully enough to determine how much of the instruction set is
> hard-wired (if any), I wonder if it would be possible to run a
> different
> instruction set entirely.
>
> -tony
>
>
Actually, with access to the micro instructions you can often
substantially improve the run-time of a given program. The Modcomp II
had the microbus accessible for use along with a number of unused
instructions. The communications instructions and floating point were
implemented using this bus.
I implemented an instruction store attached to this bus and which
allowed me to create and store new instructions. A friend working on
a CS Phd in pattern matching ginned up a program that would find
common instruction sequences in a program, deconstruct the microcode,
perform optimization on the sequence and then create a new
instruction which was substituted for the original sequence. We often
got increases of performance of 20% over the original code.
IIRC the Burroughs computers would load a different instruction set
depending on what language was being used. Tony could create a VAX
with Forth as the instruction set ;-)
CRC
Okay, looking over the web, I've seen several PDP11 machines marked
"DECdatasystem"... They don't seem to have anything in common...it's
like a random marking DEC decided to put on machines. Anyone know what
it means?
--- On Tue 10/25, Tony Duell < ard at p850ug1.demon.co.uk > wrote:
From: Tony Duell [mailto: ard at p850ug1.demon.co.uk]
To: cctalk at classiccmp.org
Date: Wed, 26 Oct 2005 01:11:34 +0100 (BST)
Subject: Re: RX01 felt pad (Tim)
> <br>> Much easier on an RX01. I don't have to remove the drive. Remove <br>> 3 screws from top board, and flip back. Remove 8 screws on lower <br>> board and remove a few cables (remembering where they go) and lift<br>> lower board and tilt towards back of unit. There thru two pretty<br>> good sized access holes are the heads and all. I simply put a small<br><br>The RX02 is like that too -- in fact the drives, chassis, PSU, front <br>panel, etc are generally the same between the 01 and 02 (there is some <br>issue of a resistor on the head connector, but...)<br><br>But since the drive is so easy to remove (take off the fan plenum at the <br>back, unplug the wiring, undo 6 screws, and it comes out downwards), I'd <br>take it out. Access to the assembly is then a lot easier.<br><br>-tony<br>
I'll remember this info for the next time I have to get to the
heads or similar. Thanks.
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>
>Subject: Re: Looking for an 8 bit FDC...
> From: Jules Richardson <julesrichardsonuk at yahoo.co.uk>
> Date: Tue, 25 Oct 2005 19:14:52 +0100
> To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
>
>Chuck Guzis wrote:
>>>Intel's 8271 looks like a possibility at the moment, but I thought I'd
>>>poll the list for alternative ideas too. FM support is of course
>>>critical - MFM is less of an issue as the host PC can handle that.
>>
>>
>> The 8271 is a pile of worms. Don't even bother with it.
>
>:-)
>
>> In a DIP package, if you want to restrict yourself to 5.25/3.5" MFM and FM
>> (but not HD) formats, the WD 1770/1772 is a nice compact (28 pin) little
>
>I've certainly got 1770 chips lying around unused in the parts box... I
>think you've just put that at the top of the list :)
>
>> Why a floppy to support your device, though? There are many high-speed
>> interfaces available to choose from nowadays. Why not feed your device via
>> USB?
>
>Rationale:
>
>I'm interested in doing this in order to archive old floppies to modern
>media, and out of the 5 or so PCs I can lay my hands on at home, none
>are happy with FM data :-(
>
>Catweasel's ruled out on grounds of cost, lack of schematics, and the
>fact that it's an internal board anyway.
>
>I need an external box of tricks so that I can easily use it to do
>archival work both at home and at the museum (and potentially other
>locations too). I know the museum PCs have serial and parallel ports,
>but not all of them will have USB; plus I'm hoping to spend zero cash on
>this and just use parts lying around at home - I'll have various serial
>& parallel I/O chips but certainly no USB stuff!
>
>
>
>As an additional thought whilst writing this (admittedly not thought
>through yet!) serial might be nicer than parallel so that at some future
>date I can dump all of the necessary firmware onto the disk interface
>box's ROM and in theory just talk to it using a comms package from the
>PC host.
>
>Lots more work in terms of understanding the various download protocols
>to do it that way, and it means that the disk interface box needs to
>understand the resultant disk image format on the PC which I'm not sure
>I like... but it does mean that all the host PC needs is a serial port
>and some comms software (which is covered by pretty much any modern-ish
>PC OS on the planet) rather than any special application to drive the box.
>
>If serial's the standard interface though it'd be zero hardware changes
>to support this in the future - it just means being stuck with a slower
>serial protocol for disk image transfer, when parallel would be faster.
>And yeah, I think we've been over this on this list before... :-)
>
>cheers
>
>Jules
If you have an older box with ISA bus there is a direct solution..
Put a 1793/2793/1770 on a ISA protoboard and run it direct from the
PC. Then all you need to write is software to make it go. There's
absolutly no reason why you cannot do that.
Allison
--- On Tue 10/25, David Gesswein < djg at drs-c4i.com > wrote:
From: David Gesswein [mailto: djg at drs-c4i.com]
To: cctalk at classiccmp.org
Date: Tue, 25 Oct 2005 18:22:26 -0400
Subject: Re: RX01 felt pad (Tim)
I just took apart my RX02 to clean them since they were getting<br>flakey. On a previous drive I just went to a craft store and bought the<br>closest material I could find, cut it to a small dot to fit in the<br>cup. Put a drop of glue in the cup and push the material in. <br><br>To get the drive out for access.<br>1) Remove from outer shell if you have the desktop unit. The top cover<br>comes off with obvious screws then ones along the side free the internal<br>unit.<br>2) Disconnect the cables to the controller board and motor power connector<br>on the back of the drive hidden by the air baffle.<br>3) Remove drive from rest of assembly. 2 screws through the air baffle<br>at the back and 4 from the top down. If you tilt the upper board up<br>on the hinge they are accesible through holes in the lower PCB. <br><br>That should free the drive. You can then lift up the little presure arm<br>to easly get at the pad.<br><br>I don't have any real RX01's so they might be
slightly different for<br>disassembly.<br><br>
Much easier on an RX01. I don't have to remove the drive. Remove
3 screws from top board, and flip back. Remove 8 screws on lower board and remove a few cables (remembering where they go) and lift
lower board and tilt towards back of unit. There thru two pretty
good sized access holes are the heads and all. I simply put a small
drop of contact cement on the holder and a very small amount on the
pad. Let both dry for about 10 minutes. THen put the pad onto the
bottom of the holder. Voila. It should work. Hardest part was keeping the little pad on my finger to stick it to the holder. It
kept falling off. It's setting up now. I will test it later.
Thanks all.
Tim R
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OK, I'm wanting to build a board with an 8 bit CPU (probably Z80,
possibly 6502) and a floppy controller IC on board with the intention of
hanging it off my PC (via serial or parallel, undecided yet) and
allowing me to read and write *most* formats from various 1980's 8 bit
micros...
Intel's 8271 looks like a possibility at the moment, but I thought I'd
poll the list for alternative ideas too. FM support is of course
critical - MFM is less of an issue as the host PC can handle that.
I've never built any kind of computer from scratch, so it'll be a useful
experience. I figure on putting just enough code in ROM to support
downloading of actual firmware to the device over whatever the link is
to the PC, as that should save a lot of headache!
Hopefully RAM requirements will be low enough that I can go the SRAM
route and avoid messing around with DRAM refresh (although IIRC the Z80
has much of the necessary stuff built in...)
cheers
Jules
I just took apart my RX02 to clean them since they were getting
flakey. On a previous drive I just went to a craft store and bought the
closest material I could find, cut it to a small dot to fit in the
cup. Put a drop of glue in the cup and push the material in.
To get the drive out for access.
1) Remove from outer shell if you have the desktop unit. The top cover
comes off with obvious screws then ones along the side free the internal
unit.
2) Disconnect the cables to the controller board and motor power connector
on the back of the drive hidden by the air baffle.
3) Remove drive from rest of assembly. 2 screws through the air baffle
at the back and 4 from the top down. If you tilt the upper board up
on the hinge they are accesible through holes in the lower PCB.
That should free the drive. You can then lift up the little presure arm
to easly get at the pad.
I don't have any real RX01's so they might be slightly different for
disassembly.
On Tue, 25 Oct 2005 20:35:37 +0100 (BST),
> ard at p850ug1.demon.co.uk (Tony Duell) wrote:
>
> Incidentally, the PALs in the 11/730 are 'protected by solder'.
> That is,
> the security fuses are intact. If you are prepared to desolder them
> from
> the PCBs, you can read them out.
>
> -tony
At one time I had a set of prints for the 11/730 and IIRC the PAL
codes were included on the schematics.
CRC
