test-drb June 2010

test-drb@ccmp.vtda.org

167 participants
232 discussions

by bear＠typewritten.org

I'm helping a local school district with a technology exhibit. They have a Dynalogic Hyperion, and are looking for the custom MS-DOS for it. Anyone who might be able to help is encouraged to contact me off-list. Thanks! ok bear

14 years, 7 months

OC/OD 48 ma transceivers

by cclist＠sydex.com

I'm working on a controller to drive some long >1m bidirectional lines that require 220/330 termination and 48 ma. drive current capability. For sake of argument, call them SCSI-1 SE (but they're not SCSI (or HPIB)). I'm finding that my choices are pretty limited. I could use a 74F621, 74FCT621 (CMOS) or a good old 75160. All appear to be within the same approximate price range. Can anyone make any recommendations? Thanks, Chuck

14 years, 7 months

Authentic PDP-11 rack available for rescue in London

by jonathan.pdp11＠gmail.com

Dear All I have a PDP-11 rack available for rescue in central London. It's just the metal rack, no computer or power supply. Sadly space is no longer available for it. It's the cream-coloured style, about 42-inches tall, with a radiused top, to match your 11/34 and RL02s. Has both sides, top, and two front blanking panels. Has a few rust spots but not too bad. Castors. It looks like this 11/94 <http://www.pdp11.co.uk/profiles/item-enlarge.ehtml?i=38>. It would really suit someone trying to achieve an authentic "cream period" PDP-11 which I believe began with the 11/04 in 1976. I might be able to find one or two more pieces, I think even an old power supply for a 11/34. Free for anyone who would like to collect it. Would require a van or at least an estate car. Any takers? Kind regards, Jonathan.

14 years, 7 months

pinout for Vector Graphic's ZCB cable

by dm561＠torfree.net

It's just a straightforward 16-pin DIP to DB25 IDC ribbon cable, DIP pin 16 aligned with DB25 pin 1. Boy, those are huge files, almost 70MB; my copy from Howard Harte's site is only 3MB (there are several revisions BTW). mike ******************************************* Date: Wed, 16 Jun 2010 08:35:50 -0400 From: "Bill Degnan" <billdeg at degnanco.com> Subject: re: pinout for Vector Graphic's ZCB cable > > I have a Vector Graphic's ZCB cable that is wired for a 9600b 8/n/1 serial > terminal. It was working yesterday, but the connections were brittle and a > few of the wires have come loose from the 25-pin connector. I can see the > spots where the solder was applied but I am not confident that I have the > correct repair points. Does anyone have the pinouts for this cable so I > can re-solder/replace? <snip> I believe this is the answer to my question page 10 of http://vector-graphic.info/vg_zcb.aspx (download/part 2) Bill

14 years, 7 months

quick test: floppy motor speed variation

by keithvz＠verizon.net

Since I've been failing miserably coming up with a working verilog PLL, I decided to do something easier tonight. I captured about 1,000 index pulses from a Sony MPF920-E(if I read date code right, it's from April 1997) with a 20+ year old floppy disk with a logic analyzer. I exported the data, and then massaged the data into some results with Excel. My average pulse was 200.487ms apart. All pulses were within 55us of each other, range was 200.464ms -> 200.519. Standard deviation was 9.46us. This sounds way way better than the NatSemi AN-505 note of 1-2%. Is anyone else surprised by this result? I was expecting differences measured in milliseconds not micros. Thanks Keith

14 years, 7 months

pinout for Vector Graphic's ZCB cable

by billdeg＠degnanco.com

> > I have a Vector Graphic's ZCB cable that is wired for a 9600b 8/n/1 serial > terminal. It was working yesterday, but the connections were brittle and a > few of the wires have come loose from the 25-pin connector. I can see the > spots where the solder was applied but I am not confident that I have the > correct repair points. Does anyone have the pinouts for this cable so I > can re-solder/replace? <snip> I believe this is the answer to my question page 10 of http://vector-graphic.info/vg_zcb.aspx (download/part 2) Bill

14 years, 7 months

Commodore C 900 documentation and software required ...

by jfoust＠threedee.com

At 02:43 PM 6/15/2010, Brian Lanning wrote: >On Tue, Jun 15, 2010 at 2:30 PM, Zane H. Healy <healyzh at aracnet.com> wrote: >> I assume most of us have never seen a C900. I need to google it, as I'm >> curious as to what it actually is. I remember seeing one at CES in '85 or so. I saw one or two since then, back in Amiga days. Secret Weapons says 500 units were produced. I would guess that CBM would've sold as many as they could, which isn't quite the same as saying they were all scrapped. I think I have an AMIX tape and tape drive in the basement somewhere, for the A2500. - John

14 years, 7 months

Senzig S-100 boards

by jfoust＠threedee.com

A year or so ago, Jim Battle passed along a tip from the brother of Don Senzig, a Milwaukee area S-100 devotee who passed away leaving a collection of old boards. I eventually received them. Here's a quick overview: http://www.flickr.com/photos/37817884 at N07/?saved=1 Are there any gems there? I'm not an S-100 collector, (although if an IMSAI fell in my lap I've take it (having helped my high school computer club build one, once upon a time.)) I'm open to ideas about disposing of these boards. I don't have any reason to keep them. - John

14 years, 7 months

Moreo n the HP82909 RAM module

by ard＠p850ug1.demon.co.uk

I've spent a bit more time looking at the HP82909 128K RAM module for the HP86/HP87 machines which I mentioned a few days ago. I think I know what the missing chips are -- a pair of '30s, a '27 and a '74. Thers's also a resistor (around 4k7?) and a transistor (TUN :-)), not fitted as well. And a mode control link or switch which enables this extra circuitry (and changes a couple of other logic signals that I've not fully investigated yet) if these parts were present, then it appears a write to location 0xFFC7 would enable or disable the internal system ROMs of the HP85/87 (bit 0 of the data written determines whether the ROMs are enabled or disabled. I don't know enough about the custom RAM controller IC in the module to know if it can be programemd to map the RAM in place of the system ROMs, or if a differnt controller IC is needed too. I am wondering what this was designed for? Developing new versions of the ROMs? Has anyone come across anHP product which could make use of this capability? -tony

14 years, 7 months

RK05 data problems with misaligned drive?

by hachti＠hachti.de

Hi folks, I'm just reviving a completely misaligned RK05 drive. I want to get it fully up and running and tested before I use an alignment pack. So I started debugging and got it to the point that I can play with the formatter. Here comes the question: The formatter (RKLFMT under OS/8) threw MANY CRC errors when reading back the freshly formatted disk. Changing the head cables at the drive proved that the problem is only with one head i.e. the failures change "side" when you change the head plugs. Now I ran the test several times. With random failing disk addresses. And they decreased and decreased... Now I've run two error-free formatter rounds. Could it be possible that new data on new tracks (keep in mind that the drive is actually misaligned by means of mechanical alteration!) suffers from interference from old tracks? That's the only reason I can see for this kind of behavior. On the other hand that would mean that I'd have to degauss the pack before I ever could use it reliable again. Any ideas? Kind regards, Philipp :-) -- http://www.hachti.de

14 years, 7 months

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test-drb June 2010