test-drb September 1999

test-drb@ccmp.vtda.org

160 participants
610 discussions

floppy controller IC (was Re: Fixing a PET?)

by pete＠dunnington.u-net.com

On Sep 30, 19:08, Tony Duell wrote: > Subject: Re: floppy controller IC (was Re: Fixing a PET?) > > I think that you are confusing DSHD and 96tpi which are not necessarily > > the same thing. Most DSDD disks will format to 96tpi (720k on 5.25"), > > Odd... I've had a lot of problems doing that. In my experience, most 360K > (DS 40 track) disks will not format to 80 tracks (and won't format on a > Sirius, or a CBM8050, or...). Interesting. I've *never* had *that* problem, except with disks that were definitely defective (weren't reliable on any drive), although I had a few really old ones that worked fine as SS but not DS. -- Pete Peter Turnbull Dept. of Computer Science University of York

25 years

DataChief

by Ferrousp＠aol.com

Anyone out there have any experience with a Data Chief. It consists of a Commodore floppy drive mated to a Seagate MFM drive in a large AT-type case and controlled by a Commodore C-64 or C-128. I have 2 of them I am restoring and would appreciate any information you might have. Thanks, Tim Knight

25 years

floppy controller IC (was Re: Fixing a PET?)

by Glenatacme＠aol.com

In a message dated 09/30/1999 1:05:05 AM Eastern Daylight Time, donm(a)cts.com writes: > I think that you are confusing DSHD and 96tpi which are not necessarily > the same thing. You might be right (about my confusion) ;>) > Most DSDD disks will format to 96tpi (720k on 5.25"), > even the generics. But I have yet to successfully format a DSDD (360k) > to 1.2mb or a DSHD (1.2mb) to 360k. ISTR formatting DSHD diskettes to 360 KB in an emergency (we're talking IBM-type pcs here) but only after hitting them with a bulk tape eraser to wipe them clean, and then using the proper DOS FORMAT parameters . . . Then again, I've been wrong before ;>) Regards, Glen Goodwin 0/0

25 years

RCA 1861, NTSC and a DEC VR-201

by ethan_dicks＠yahoo.com

--- Tony Duell <ard(a)p850ug1.demon.co.uk> wrote: > > So how can I soup up the output of the 1861 to drive a 75ohm input? > > Well, if you want the easy way, there are some lovely Elantec chips > (EL2001, EL2002, EL2003, IIRC) that are unity-gain buffers with some > high bandwidth that are designeed to drive video cables. They're pretty > easy to use, but you probably put them on a ground plane, and you > _certainly_ need to decouple them. I am unfamiliar with these chips. > If you want a kludge, how about opening up the VR201 (it's one screw on > the back, extend the leg, and pull the shell off) and looking for a 75 > Ohm resistor between the video input and ground. I have the PCB for a VR-201 right here (I dropped one a year or so ago, blowing the CRT. :-P ) > Try removing it -- it > may increase the impedance enough for it to work, although the VR201 is > now non-standard. It's been a long time since I've been inside a VR201, > so I can't be sure this resistor exists, but it's worth a try. Looking around, I don't see anything that is obviously that value. Going around the board, since we've been discussing internals, besides the external bright/contract pots, there are pots labelled (on the insulating paper) VH, H, VL, HH, PH, FOCUS and CUTOFF. There is an unlabelled variable resistor near the input connector. On the input connector, it looks like this from the PCB... | | | | | 9 10 11 12 13 14 15 | | | 1 2 3 4--5--6 7--8 Pins 4, 5, 6 and 13 appear to be ground Pins 7 and 8 appear to be +12V Pins 14 and 15 go off to the keyboard connector Pin 12 appears to be video. It goes off under the connector, through a 0 Ohm jumper, across a Yellow-Purple-Gold-Gold resistor, then tied to ground via a Grey-Red-Black-Gold (might be Sky Blue-Red-Black-Gold) and then through one of the rear pots. I would spec the values, but I'm not used to such odd colors in the significant digits of resistors (just as tolerance bands). Would a EE care to translate these? Might that second one be 92 Ohms? Could the first one be 7.5 Ohms? I'd rather not have to mod a VR-201. I want to have a nice, portable solution, even if I have to make a mod or two to the VIP. Any easy transistor/resistor hacks to drive more video current? Thanks, -ethan ===== Infinet has been sold. The domain is going away in February. Please send all replies to erd(a)iname.com __________________________________________________ Do You Yahoo!? Bid and sell for free at http://auctions.yahoo.com

25 years

HP3000 Gear Available In Seattle Area...

by af-list＠lafleur.wfi-inc.com

If anyone is interested in some HP3000 gear around Seattle, please let me know. The guy with the stuff doesn't want to be contacted directly and is looking for someone who can pick it up locally. I only wish I had time for a road-trip! Bring a truck! He's got: 1 - Series 37 (parts mostly because of a bad power supply) 1 - Micro 3000 GX (4 Meg + 300M Disc + 9145 + 8 ports) 1 - Micro 3000 RX (4 Meg + 300M Disc + 9144 + 16 ports) 3 - 7937 - 627M HPIB disc drives (BIG) 2 - Standalone 9144 drives 1 - 7980 - 6250 BPI Tape drive 1 - 7958 - 130M Disc Drive Nice gear... Cheers, Aaron

25 years

Media interchange sillinesss (Was: floppy controller IC (was Re:

by cmcmanis＠mcmanis.com

Fascinating stuff, the old "HD/DD/SD" debate rages even today. Fortunately half of the conversation gets filtered on this end. Fred's absolutely correct. I can add only one Factoid that was true in 1986 which was that Sony and Verbatim had both admitted that they were only made double sided diskette media and the single sided disks were in fact double sided capable. But _nobody_ ever claimed they used a single emulsion for both HD and DD disks. For formats where the emulsion was the same for SD vs DD disks they did use the same media. --Chuck

25 years

Classical Computing software?

by yoda＠isr.ist.utl.pt

Hi. Are there any repositories on the net containing ancient software? For instance, tape dumps of very old UNIX versions, or Symbolics LISP system. Is anyone collecting this kind of stuff in elecronic form? Cheers, -- *** Rodrigo Martins de Matos Ventura <yoda(a)isr.ist.utl.pt> *** Web page: http://www.isr.ist.utl.pt/~yoda *** Teaching Assistant and MSc Student at ISR: *** Instituto de Sistemas e Robotica, Polo de Lisboa *** Instituto Superior Tecnico, Lisboa, PORTUGAL *** PGP fingerprint = 0119 AD13 9EEE 264A 3F10 31D3 89B3 C6C4 60C6 4585

25 years

RCA 1861, NTSC and a DEC VR-201

by mtapley＠swri.edu

ethan said: >Yellow-Purple-Gold-Gold resistor, then tied to ground via >a Grey-Red-Black-Gold (might be Sky Blue-Red-Black-Gold) and then through one >of the rear pots. I would spec the values, but I'm not used to such odd >colors >in the significant digits of resistors (just as tolerance bands). Would a >EE care to translate these? Might that second one be 92 Ohms? Could the >first one be 7.5 Ohms? Puzzles me too. Silver 1e-2 Gold 1e-1 1 Black 1e0 First 2 digits give mantissa, 2 Brown 1e1 3rd digit gives exponent, 3 Red 1e2 4th band gives quality of resistor (if present), else +/- 20% 4 Orange 1e3 (silver = +/- 10%, gold= +/- 5%, red = +/- 2%) 5 Yellow 1e4 5th band (if present) gives reliability (mil-spec, etc.) 6 Green 1e5 7 Blue 1e6 Example: red-yellow-orange-gold = 2,4,10^3, 5% = 24k Ohm, 5% 8 Violet 1e7 9 Gray (From Horowitz & Hill, The Art of Electronics, 1st Edition 0 White pp. 645-646) No I'm not an EE but with Horowitz and Hill *anyone* can play an EE on TV, so here's my guess: Yellow-Purple-Gold-Gold : 5 8 1e-1 5% = 5.8 +/- 0.29 Ohms Grey-Red-Black-Gold : Confederate Oil-filled resistor :-) ok, ok.... 9 3 1e0 5% = 93 +/- 4.65 Ohms Ok, if a *real* EE hasn't already appeared, please do so and set me straight. - Mark

25 years

RCA 1861, NTSC and a DEC VR-201

by pete＠dunnington.u-net.com

On Sep 29, 19:02, Ethan Dicks wrote: > Pin 12 appears to be video. It goes off under the connector, through a 0 Ohm > jumper, across a Yellow-Purple-Gold-Gold resistor, then tied to ground via > a Grey-Red-Black-Gold (might be Sky Blue-Red-Black-Gold) and then through one > of the rear pots. I would spec the values, but I'm not used to such odd colors > in the significant digits of resistors (just as tolerance bands). Would a > EE care to translate these? Might that second one be 92 Ohms? Could the > first one be 7.5 Ohms? Yellow-Purple-Gold-Gold = 4.7 ohms 5% tolerance Grey-Red-Black-Gold = 82 ohms 5% tolerance Blue-Red-Black-Gold = 62 ohms 5% tolerance The last is rather unlikely, since it's not an E12 or even E24 preferred value. -- Pete Peter Turnbull Dept. of Computer Science University of York

25 years

Commodore favourite pre-Windows system

by SUPRDAVE＠aol.com

In a message dated 9/30/99 9:54:17 AM US Eastern Standard Time, kh240463(a)stmail.staffs.ac.uk writes: > There's a poll at www.windrivers.com on what is your > favorite "pre-windows" system. At present the Commodore > 8-bits are in first place with the Amiga in second. > those numbers have got to be bogus. probably some shills involved. there were way more apple ][ series computers made than amigas, yet the numbers are really skewed...

25 years

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test-drb September 1999