test-drb

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101090 discussions

by drlegendre＠gmail.com

As part of my C-64 RS-232 to M15 60mA CL project, I've put together a simple MAX232 based interface to connect the TTL levels on the C-64 to the standard RS-232 +/- levels. Is there any reason that I can or cannot install LEDs - on either side of the MAX232 converter - to give some indication of line status? Specifically, a pair of LEDs, one each for Tx and Rx lines, to blink / etc. as line status changes and data moves. I don't see any obvious issue - but I can conceive of a situation where it might screw up the line in some way I haven't considered. Comments?

10 years, 9 months

Silent 785 docs?

by jwest＠classiccmp.org

I've got a TI Silent 785 I'm trying to get configured/running. I see docs on bitsavers for the earlier models, but not anything in the 780 series and outwardly they do appear to be somewhat different than the 700 series. My google searches don't return joy either. I'm particularly looking for serial port configuration. Anyone have operators and/or service manual for the Silent 785? J

10 years, 9 months

VT100 preventative maintenance?

by earl＠retrobits.com

Hi all, I have two VT100 terminals. Both of them work just fine. Should I leave well enough alone, or is there preventative maintenance that should be done? For instance, should capacitors be proactively replaced. In general, I'm thinking about things that, if they fail catastrophically, would cause collateral damage. Thanks! - Earl

10 years, 9 months

5.25 floppies that read but don't write

by marc.verdiell＠gmail.com

> Do we know the make/model of this drive? It's a Chinon FR-506 (NOT an FZ-506) >On 5.25" HD drives, pin 2 is generally a drive *input*. That is, the >host telegraphs what's needed, not the drive. Indeed, you have to be careful to put the right media and issue the proper density specific format command yourself, unless you work at the default of the drive, which in this case is HD. But I did, and I double checked the computer was outputting the right density signal on pin 2 on format and on write. Unfortunately the drive didn't respond correctly for writes in any settings I tried (auto or fixed density). On reading, from what I saw, the computer (at least mine) just tries both densities a couple times until it can read something. If there is some good data it declares success and keeps the pin 2 at the level that works for the rest of the session. There the news was better, the drive responded correctly to the pin 2 when it was set in auto, but incorrectly when it was in fixed HD (reading only in DD instead). So I left it in auto. At this point I'll declare this drive non functional, though still OK as a dual density, read-only drive... And look for a better HD one. My other 5.25" 360k DD 48tpi/300RPM drives read and write OK, so I have a working solution at low density. I want to recreate LIF drives for HP's, writing DD is what I need most anyhow. Thanks for the help, you pointed me in the right direction each time.

10 years, 9 months

9-Track 1/2" Tape Drive Recommendations?

by afahimi＠alumni.usc.edu

Hello All, Recently I came across a complete Pertec interface (card, manual, software, and, cables) thanks to list-member Shaun. Of course what is the point of having an interface if you have nothing to interface it to! So I've been looking at, and learning a bit, about 1/2" tape drives. I've also looked into acquiring one. But before going down this path I wanted to see what pitfalls, warning signs, etc. I should be on the lookout for. I am looking for a unit mostly to experience the tech and to play around with. I do not plan on recovering data from any particular system or format. However, it would be nice if I could setup a system that actually worked for backups of say an IBM AT for demonstration purposes. Having read some old InfoWorld and PC Mag articles I can see there were a number of tape drive manufacturers well into the early 90s. Based on the reviews the Cipher and Qualstar units seem to be well suited for my purposes. Any other brand/models I should keep an eye out for. I know IBM also had some 1/2" 9 track tape drives (9437 and 9438) but neither was a Pertec interface from what I have gleaned. The 9347 used a proprietary interface and the 9348 used HVD SCSI which is atypical. There was apparently a 9348-012 model which used narrow SCSI so should interface with a standard Adaptec card. However, I have not been able to determine if it used standard SCSI commands and could be accessed say with a tape backup program under Windows 9x/NT or DOS. Of course the biggest problem is finding one locally in the LA area. Unfortunately my only resource is eBay and prices there are definitely not hobbyist friendly (not to mention shipping). If anyone has a line on a working drive in the LA area (to save on S&H and avoid the dangers of shipping) or a reasonably priced one elsewhere I'd appreciate it. TIA for any help.

10 years, 9 months

More on manuals plus rescue

by tshoppa＠wmata.com

I certainly feel bitsavers is a good model, and although I'm physically not too far away from the stuff, I'm not sure I have much to offer other than disk space on a server for staging. http://ascii.textfiles.com/archives/4695 (previous link: http://ascii.textfiles.com/archives/4683 )

10 years, 9 months

Data I/O 29B

by bpettitx＠comcast.net

I have a small batch of Data I/O EPROM burners. Trying to test them out and ran into a nightmare. They require a pin family and size parameter. But in none of the documentation is there any mention of what these values are. There are some generic pinouts, which are almost useless because Data I/O changed the definition of several pins. Then the manual says to get your part's timing chart and compare them to 409 pages of timing charts to find the family type! Nothing is mentioned anywhere on how to calculate size parameter. There should be a chart or document somewhere that gives the parameters by model numbers like 2516, 2764, etc. Anyone know of a document like this? Anyone have experience with the model 29A&B, Model 19, Model 100 gang programmer, etc. At this point, without better data, these 11 -12 deveces are heading for the scrap pile. This is the poorest documentation I've ever seen on a piece of test equipment. Billy Pettit

10 years, 9 months

5.25 floppies that read but don't write

by marc.verdiell＠gmail.com

Chuck, I looked at the pin 2 signal and resulting drive behavior. It doesn't properly auto-switch between densities as it should. It does switch it for reading, but not for writing. Below is the full story. There is one jumper that controls DD/HD switching mode. In the auto position, I can read both HD and DD formats (I use the right diskettes for either format). You can see the computer on pin 2 (density select) trying both positions, settling on the right one (high for HD, low for DD), and reading the disc correctly. That's great. But when writing, although pin 2 goes to the right level, the floppy seems to ignore it. It will always write at DD, and refuse to write in HD (no signal at the head). Interestingly, in the fixed density position (should be HD only), it WILL write at 1.2M HD! The write signal does appears at the head. Unfortunately in this setting it will NOT switch the reading, get stuck reading only DD and fail on HD. So I can either have the reading HD or the writing HD, but not the two at the same time. That's why a regular format fails. The density switching logic seems to have a problem. Rather than track down which IC or transistor failed on the board it might be much simpler to get another 5.25 floppy. In the meantime my understanding of these simple critters has improved a lot. Marc >At high density, have you taken a good look at pin 2 of the floppy >interface? Have you checked to see if pin 2 is configured (via jumpers) >as "density select"? >--Chuck

10 years, 9 months

Looking for Vintage Gold Lead LEDs for SCELBI project

by mail.nickallen＠gmail.com

Hey everyone, I am looking for some vintage Gold-Lead clear LEDs that light up red for a Scelbi project I am working on for VCFMW. Will need 29 of them if you have them, willing to trade or buy them, thnx!! -Nick

10 years, 9 months

Data I/O 29B

by jnc＠mercury.lcs.mit.edu

> From: wulfman > I have a modified dos program that talks to the data i/o > its the one that they sold with the unit but only ran on a 286 > ... > the modified one i have works in windows 7 in a dos box I seem to recall that I downloaded some software to run my 29B (although I have yet to work with it extensively), and that it did run in a DOS box under Windows 98? Is that the '286' one you're referring to? If so, maybe that won't run in a DOS box under the later versions of Windows? Or maybe I have a different program from the one you're talking about? (Or maybe I somehow downloaded an already-fixed version?) > if your interested i can send it to you Other than running under Windows 7, does it have any other improvements? If so, I might be interested. Whatever the case, if you would like someone to host it for open download, let me know. Noel

10 years, 9 months

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