Re: Recharging old batteries

Posted on 2024-12-12, 07:40

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Please please please do not attempt to recharge Tadiron Lithium Thionyl Chloride (LiSOCl2) batteries. In fact don't play with them at all. Read the MSDS for these devices. They are nasty with toxic reactive electrolyte and unforgiving behaviour when abused, and remain a threat even when dead. Unless …

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Re: MFM drive error but in other language than BIOS

Posted on 2024-12-07, 09:24

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Building on Deunan's post... The message is possibly being spat out by the MBR code. The MBR code is probably immune from any geometry issues (you will always be able to read track zero, head zero, sectors 1-17, in spite of any geometry issues), but if the boot sector of the active partition which …

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Re: Backing up a Hardcard+ from a 5150

Posted on 2024-11-04, 14:27

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

A 8 bit hardcard is just an 8bit MFM or RLL controller card with a bracket for a matching hard drive. In the mists of time (sometime in the 2000s) I took an image of an ST238R hard drive by plugging the ST11R adapter into a 486 box running an old version of Linux (most likely Slackware 4.0). I …

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Re: Repairing a M48T86PC1 RTC chip

Posted on 2024-10-29, 05:52

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Why are people still drilling two holes when GND on the battery is connected directly to the GND pin... Your average 48T device is usually in a socket. Soldering to the ground pin makes it difficult to insert. A flying lead to a convenient earth on the PCB leashes the device to the board. For …

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Re: Repairing a M48T86PC1 RTC chip

Posted on 2024-10-28, 20:39

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Additional hint: there's a 32.768kHz crystal soldered to two similar pins at the other end of the cap.

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Re: Does the dimension of a crystal/tuning fork matter?

Posted on 2024-08-24, 06:38

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

In my experience, 32.768kHz crystals only come in one size. You haven't left the leads too long, so I wouldn't expect any issues.

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Re: Goldstar 386, CMOS battery voltage

Posted on 2024-08-07, 13:25

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Very similar model, but there is no info about a battery voltage. https://theretroweb.com/motherboards/s/goldstar-gs318 There is - but it needs some navigating, and even then it doesn't leap out of the page... Click on the chipset (82C836) which takes you to https://theretroweb.com/chipsets/239 …

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Re: Used EPROMS I got may be of value

Posted on 2024-06-09, 20:38

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

SOP for me is to download the EPROM contents to a file and then wipe for further use (or stick in a "OK for reuse tube"). The file containing the data then gets renamed to "something dot ROM" (where "something" reflects where the device came from or the label on the device) and then "deduped" …

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Re: Fast Ethernet on ISA

Posted on 2024-05-26, 19:10

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Full Duplex being slower than Half Duplex clearly means mismatch. Did you ever run these tests on the 3C509B? I've been forcing FD on my cards but now I wonder if this actually works properly with the dumb switch I have, or it is slowing things down as well. If the card sends a packet while …

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Re: ST MK48Z02B-12 battery mod needed

Posted on 2024-05-15, 16:25

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

weedeewee wrote on 2024-05-12, 19:16: I assume you saw this eevblog forum post ? https://www.eevblog.com/forum/microcontroller … 211/#msg2639211 🤣 - another one of my NVRAM brain dumps....

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Re: ST MK48Z02B-12 battery mod needed

Posted on 2024-05-12, 07:59

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

A 48z02 is effectively a battery backed 6116 2k x8 SRAM. (No RTC, and no compatibility issues like the 48T02). Any battery backed device with the same pinout will do the job. The device itself probably has 26 pins with two pins emerging from the top or bottom of the device (rather than from the …

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Re: What Floppy disk drive for BBC Master?

Posted on 2024-04-20, 12:38

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Three sets of golden rules for BBC/Master floppy disc drives: 1) Use a Gotek - its easier 2) Use a Gotek - when you get bored with the BBC/Master you can repurpose it for other old school kit 3) See below :) Discs and media: 5.25" drives - use SD or DD media, not HD. Put another way, don't use 1.2Mb …

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Re: SCSI Ultra adapters (Like SATA to IDE, but for SCSI)

Posted on 2024-04-20, 07:30

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Boot the Sun boxes over the network using NFS. That way you can use your existing modern storage, and the lack of SCSI drives goes away. Keep the size of the NFS shares realistic - I've found that with older versions of Solaris installing packages can fail with "insufficient space" caused by code …

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Re: 3COM 3C509C-TPC network adapter - question to owners

Posted on 2023-09-20, 07:44

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It's probably a pull up or pull down resistor. Note that it is fed from elsewhere, (probably the 3com ASIC), so I'd be tempted to leave it empty, and give it a test. If the card didn't work properly I'd fit a 10k resistor. "Give it a test" would mean fitting an EPROM, programming the card with the …

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Re: Happauge usb tv tuner capture 8-bit computer output?

Posted on 2023-08-23, 22:13

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

If your device can output composite video, then capture that. You only capture RF if you can't get the composite signal. Tap off the modulator input if you have to - that's what I did back in the day with a ZX Spectrum (only had RF output, soldered a phono lead onto the modulator input with the …

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Re: What's this strange SCSI card?

Posted on 2023-06-04, 10:13

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

May have some more clues regarding the "fits in a pci slot, but isn't a pci card" card The two programmable devices say GRETAGMACBETH and the PCB has the markings GRETAG, so working on the basis that this is a card made by Gretag and it does "SPMI", i was persuaded to '"gretag" spmi' (without single …

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Re: How to use a SYS68k CPU-6A Force Computers card?

Posted on 2023-05-26, 12:50

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You will probably need a vme backplane plus a suitable power supply, and maybe an MSM (mass storage module) card to hold one or two SCSI hard drives. (Force SPARC boards did have an option to jumper SCSI via the backplane or the HD50 connector on the front, the 68k may differ. The MSM used what …

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Re: Can someone help identify this internal Sony floppy drive?

Posted on 2023-05-08, 22:46

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Look at the solder blobs to the right of the connector marked SH19. Remove the DS0 blob and make the DS1 blob and try again with a PC.

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Re: Connect a parallel zip to two computers at the same time.

Posted on 2023-01-19, 23:24

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The passthrough connector is to pass the LPT port on a PC through to a printer, so you can hang a zip drive and a printer off one PC. This isn't like SCSI, where (in theory) you can hang one drive off two computers (provided each PC SCSI card has a different id - the default HBA SCSI id is 7).

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Re: Dell Dimension 486SX 25 processor swap to 486DX. How do I change the bus speed?

Posted on 2023-01-12, 22:44

by

by mdog69

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The empty Y1 position looks like a space for a larger/taller format crystal installed in the same holes as the crystal installed below it, but with the legs bent 90deg so that the body of the crystal lies parallel to the PCB. The two pads are not connected and are there to mechanically attach the …

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