Whit3rd
  • Member for 5 years, 1 month
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  • Seattle, WA
Did personal computers ever support 8" floppies?
14 votes

The old NEC APC was equipped with two 8" floppies, with about 1.2 megabyte of storage on each. Museum system here. In the early 1980s, it was considered a fine performer, but Macintosh and Windows ...

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Magnetic tapes as a random access medium?
Accepted answer
12 votes

DECtape was used that way; it was wide (0.750 inch?) magnetic tape, on very small reels, so it didn't take forever to find a sector. PDP-8 and PDP-11 systems from Digital Equipment were the likely ...

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How was the wiring color order of the modular connector determined?
Accepted answer
11 votes

It's done that way because the 6p connector (standard telephone wiring, with either two wires:== RJ11 or four wires:==RJ14) puts TIP and RING on the center two positions, with TIP2 and RING2 (for a ...

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Safely adjusting CRT while it's on?
10 votes

Isolating transformer won't help; the HV parts just have to be avoided when making the picture adjustments (mainly, that's not hard). All the red/green/blue circuitry is innocuous circa 50VDC stuff, ...

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PAL NES in USA, 50Hz vs 60Hz
10 votes

Rather than convert the NES, just get a PAL monitor. The common auto backup video systems use an NTSC/PAL switchable monitor, available for not much money.Backup monitor 7" It is also possible, ...

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Macintosh LC II power supply clicking
Accepted answer
8 votes

The ticking indicates restarting of the power supply by the controller, probably due to a short. The short would have to be on the OUTPUT (low voltage) side (shorted AC-side devices would have ...

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What's the pitfalls when trying to connect a new SCSI hard drive to an old SCSI bus?
7 votes

Almost all SCSI devices are either 8-bit wide and have a 50-pin connector with single-ended (open collector, no differential drive) electrical signals, or are 16-bit wide, using LVD differential ...

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Why did 1970s front panels prefer momentary toggle switches to push buttons?
7 votes

There are usually multiple contacts made when a switch is operated (it's called bounce). Debouncing a large number of (SPST) pushbutton switches is difficult (requires lots of components, or even a ...

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Was photographic film ever used for digital data storage?
6 votes

Yes, of course photographic film was used for data storage, but not necessarily computer data storage. A seismometry network has dozens of stations reporting to a central site, and it used to be (...

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How to work around the PRAM battery for a "Titanium" Powerbook G4
5 votes

The PRAM battery for a Titanium Powerbook G4 is rechargeable, it might not need replacing (though will certainly go flat on the shelf). The cells are rechargeable lithium/vanadium pentoxide 3V coin ...

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Original Mac capacitor inspection
5 votes

The vertical sweep nonpolar capacitor (C1) is the most likely to fail. No inspection is complete without checking also the CRT yoke connector (plastic four-pin connector) for cracked solder joints, ...

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Using VHS/MiniDV/CompactCassette as digital data storage?
4 votes

The VHS (and Beta) protocols required signals to mimic frames of television picture, so are hardware-supported in complex ways. Digital use (possible exception of PCM audio) was rare. The ...

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Can a standard ATX power supply be used on a Macintosh Performa 476?
4 votes

The power supply is mainly 5V 3.75A (for all the logic), with +12V 0.78A to run the hard disk, and -5V 0.075A to run the serial ports (printer and modem). Ethernet cards exist, but the hard disk drive ...

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What is the maximum voltage of high voltage differential SCSI?
Accepted answer
3 votes

HVD in the SCSI standards was 'according to RS-485', which allows up to -7V and +12V on the differential wiring, though limits the difference signal to the (0V, 5V) range. There is a separate line ...

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iMac G3 - AirPort Card Port
Accepted answer
3 votes

The MacOS versions that used Apple 802.11g Airport cards were compatible with Broadcom's chipset for that standard (a bit of a speed improvement over 802.11b). There were PCMCIA plugin cards for ...

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Cleaning buckling spring keyboards
2 votes

Mostly, if the keys aren't sticky, or malfunctioning, you only need superficial cleaning. A bit of isopropanol (or alcohol-based sanitizer) moistening a rag will dissolve most finger residues ...

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Reviving a Powerbook 145B, but it still struggles to power up correctly
2 votes

Startup is when the CMOS data is accessed; it's likely that you will need to reset PRAM (parameter random access memory, aka CMOS) by holding down command-option-P-R for several seconds after powering ...

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Why are old computers so vulnerable to temperature changes and moisture?
2 votes

The specifications for most computers include (or used to) prohibition of 'condensing moisture' conditions. The 'condensing moisture' means dew. On a ship, below waterline, if there's no air ...

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Were any external disk drives stacked vertically?
2 votes

Yes, of course external disk drives were often stacked. The LaCie 'Joule' external disk tower was a vertical stack/rack for drive modules,depicted here and many external disk cases were given ...

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Is it possible to upgrade original iMac (1998) memory (RAM) to above 256 MB?
2 votes

Yes, it is certainly possible. Bondi iMac (233 MHz) takes two SO-DIMM memories, of the PC100 type, one of which must be low-profile (circa one inch high) while the other may be high-profile (two ...

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What was the 2nd best selling computer ever?
2 votes

Hard to be sure; the old translucent iMac G3 (gumdrop models) were slightly different, but sold for five or six years, circa 2 million per year. Should we count colors as differences? CPU speeds? ...

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CRT Geometry Adjustment
2 votes

The vertical and horizontal deflections in a CRT are not entirely independent. There is a 'pincushion' effect that is commonly adjusted using a 'pin' or 'pin amp' labeled control, which is usually ...

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How do I connect a modern display, keyboard, and mouse to a Power Macintosh 6100?
2 votes

The HDI45 connector for video is essential (it is nearly impossible to tack-wire to the main circuit board). Buy a video connector adapter. They're still for sale Pi mfg. for example and probably ...

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How to renew and re-ink old printer ribbons?
2 votes

Reinking with a felt roller, motorized spindle, and a small amount of stamp pad ink was a common practice. Less common, was WD-40 spray, or an eyedropper with some kerosene (available odorless for ...

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Connectors for green screen versus color monitors
2 votes

It can be done, but in addition to connectors, there are three signal issues. First, the refresh rate can be inflexible (and if it's different, there may be inadequate adjustment capability). ...

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Adjusting focus for old CRT monitors
2 votes

Focus is a high voltage function (but not as high as the main color monitor anode, which is 24 kV or so). Locate the 'focus' knob (which, if you are careful, can be adjusted while the set is under ...

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What were the applications of 5/6-bit serial port formats?
2 votes

Stock tickers date from 1863 (a variant was Edison's first successful invention in 1869). The text-output ones only printed 32 characters, so would have been a 5-bit application... which is possibly ...

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What early home computers have more than one CPU, where both could be used by the programmer?
2 votes

The NeXT computer (1988) had a second CPU, a Motorola 56001. There were a number of Macintosh models with the 'AV' suffix that sported a Motorola 56000 digital signal processing second processor. ...

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Capacitor replacement on European 220 volt Mac 512K And Plus
1 votes

If you need to repair two Macintosh 220V Power/Sweep boards, #661-76214 (the power and video parts), the only likely replacement capacitor needed would be the vertical sweep (on 120V boards, that's 3....

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Speed of early ROM versus RAM chips
1 votes

A DEC VAX of the early 1980s used ROM to store its microcode, but on power-up transferred all that into SRAM (static RAM). SRAM was faster than either ROM or DRAM (dynamic RAM), but more expensive ...

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