Optimizing DOS memory

Optimizing DOS memory

After watching some 486 build videos, it became clear to me that optimizing DOS memory is a lost art. Yes, I made some boot menus and custom DOS boot disks in my day, but for power users, that was usually a last resort. Memory managers usually free up more than 600K of conventional memory so DOS programs run great. Here’s how to use them.

The key is using HIMEM.SYS and EMM386.EXE in your config.sys with certain recommended parameters. These programs move device drivers and memory-resident utilities out of conventional memory to make room for memory-hungry DOS programs. Using HIMEM.SYS and EMM386.EXE is a bit of a lost art, so let’s see if we can un-lose it.

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PC DOS vs MS-DOS

PC DOS vs MS-DOS

DOS was a bit of an oddity, in that you could buy it from either Microsoft or IBM. The two were never quite identical, but were always mostly interchangeable. The differences grew larger at version 6, but they were still more alike than different. Let’s take a look at PC DOS vs MS-DOS.

IBM and Microsoft collaborated on DOS, and both had the right to market it. IBM sold its version as PC DOS, while Microsoft sold its version as MS-DOS. And for a time, IBM was happy just to sell PC DOS to owners of true-blue IBM PCs. But in 1993 it changed.

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What is retro in computers?

What is retro in computers?

What is retro in computers? It’s a fair question, because there’s a fine line between junk and treasure when it comes to old computers. And the answer definitely depends on who you ask. It means the computer is old enough to be collectible, but there’s no universal standard for “old enough.”

As a general rule, if it’s obsolete and no longer being made, someone considers it retro. But not necessarily everyone will, so there certainly are degrees of retro when it comes to computers.

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Sega Genesis power supply specs

Sega Genesis power supply specs

When it comes to the Sega Genesis power supply, there’s one important thing to remember. You can use a Genesis power supply in a NIntendo NES, but the reverse is not true. The NES isn’t picky about its power, but the Genesis needs 9 volts DC and the right polarity.

The original Genesis power supply connector is the same size as a Nintendo NES, but the Genesis requires 9 volts DC, center negative, and 1 amp, though 1.2 amps is better. A non-Sega adapter is fine to use as long as it meets these specs, but using AC or the wrong polarity will damage the game console.

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Fix a VIC-20 displaying the wrong colors

Fix a VIC-20 displaying the wrong colors

It’s not terribly uncommon for a VIC-20 to display colors badly, or just downright wrong. Most people attribute this to the nature of the machine. But it’s possible to adjust the color to get something closer to what screenshots in vintage magazines suggest the VIC-20’s display really looked like. Here’s how to fix a VIC-20 displaying the wrong colors.

The VIC-20 never had great color rendition to begin with, but as the components age, the color can drift even further. The VIC-20 has two potentiometers on its motherboard that you can use to adjust the color.

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Computer game cartridges

Computer game cartridges

Typically we associate game cartridges with consoles, but for a time in the 1980s, computer software, especially games, were also distributed on cartridge. Here’s why computer game cartridges fell out of fashion.

Computer game cartridges were convenient because they loaded quickly, but their high cost of production led publishers to prefer disk or tape. There was also some concern that repeatedly removing cartridges would wear out an expensive computer.

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Incorrect DOS version: How to fix it

Incorrect DOS version: How to fix it

If you mess around with DOS long enough, you’ll eventually try to run a program and get an error message that says Incorrect DOS version. This means you’re trying to run a program designed for a version of DOS other than the one you’re running.

The best solution is to run programs under the same version of DOS they were designed to run under. But when you can’t do that, as long as you are running DOS 5.0 or newer, you can use the SETVER command to lie to the program and bypass the error check. The program will run, though there is a risk it may not be fully compatible.

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