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Recent content by per

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    5 1/4” 720kb Floppy Drive Why? when? Where?

    I know for certain that the Olivetti M24 did at least use 80-track double-sided double-density drives, and could come with them in a stock configuration. Maybe the American edition, the AT&T PC 6300, used it too.
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    Tag on track 41 of some floppy-disks

    I am going through and once and for all properly archiving my collection of floppy disks, and from time to other I come across 48tpi disks with a peculiar 128-byte FM-modulated tag on head 0 of the 41st cylinder. Sometimes it is also accompanied by empty tags on head 1 and both heads of the 42nd...
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    The 'test pattern' of the Motorola MCM6830L7 ROM

    I recently got myself a MEK6800D1 I decided to get back up to working condition. After doing some research, I figured that the MIKBUG and MINIBUG portions of the ROM are well documented, but the Engineering Note 100 only lables the last 256 bytes of the ROM "Pattern Data", without ever...
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    Trying to figure out the ND/SINTRAN floppy-disk file system

    I am at the time working on imaging some 8" floppies written by a Norsk Data machine once, and right now I am trying to figure out the file system. I do find something that looks like a directory structure on the 77th track, but I am having problems finding any information what the numbers mean...
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    Code in Boot Sector

    I was looking at a disk image for the Tiki-100 the other day, and one thing that struct me is that in the end of the boot sector of the latest version of the system there's always the following code-snipplet: isk * ; * Forms: * ; * JUMP <adr> Call at <adr>;<adr> is in...
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    HP Vectra QS-series PSU pinout

    I got hold of a Vectra motherboard not too long ago, and am thinking about getting it up and running. This motherboard is very particular in that it has a 19-pin connector for the powersupply, where one pin is used as key, 15 pins for power and 3 pins for the battery. I have never seen this...
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    Tempustech F82C100 card

    Recently I got hold of this interesting card. It sports a V20, and by the chipset it should be a PC compatible. However, trying it out this turned out more interesting than expected. Mainly, it turns out the ROM is not a BIOS, but features some kind of firmware for some embedded application...
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    FDD choir (or What to do with FDDs of the 2000's)

    This is just a little pet-project of mine. Last year I built the first cluster, but 10 drives* was not enough to cover the tones of an average song. Now I've upgraded with a second cluster, and now you can finally start to get a grasp on what's playing! (* several drives are used for...
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    32MB RAM in 486, cache problems?

    Some time ago, I maxed my 486-25 systems RAM from 20MB to 32MB RAM. The first thing that happened was that EMM386.EXE hung during memory testing, unless I disabled cache for RAM above 16MB in the CMOS settings. I've tried to troubleshoot a bit. Everything seems to work fine with the new RAM...
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    Intel ICE-80 board pair (Intellec bus)

    I recently got hold of the pair of Intel ICE-80 boards, much like the ones pictured on this page: http://www.classiccmp.org/hp/multibus/multibus.html I'm curious to see if there is any interest in this kind of development gear at all. At the heart of the system is an 8080, with 256 bytes of RAM...
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    About the NCR Decision Mate V

    A friend of mine recently found an old NCR DM5 at his workplace. The machine is lacking a keyboard, and has no expansion cards. So from what I understand, this is a very expandable Z80 machine with NEC uPD7220 graphics. Is it worth picking up even though it lacks a keyboard and expansions are...
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    Tiki-100 Computer Overview/Teardown-video

    I recently made this overview/teardown review of the Norwegian Tiki-100 computer from 1984. In this video, I go over the design, the hardware and at the end there is a demonstration of some simple software for it. Enjoy! (This machine was, due to a decission by the government, popular in...
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    The PC+ missing BIOS

    Recently I came by a "The PC+" turbo-XT motherboard, but unfortunately it has no BIOS. Does this machine require a custom BIOS, or would any clone-BIOS work just fine? I have little experience with XT and turbo-XT clones, and I have no idea on how much variation there was between the different...
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    Non working C64

    I got a NTSC C64 now, but it has certain problems. When powered on, it sometimes sets up a frame, sometimes not, but in most cases it will fill the display with random symbols and characters before either going to black screen or lock itself in some loop where the screen flickers between two...
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    Breakout Box for the IBM Music Feature Card

    http://www.ebay.com/itm/141800745241 Not mine, but the person selling it ships worldwide. With this box, the IMFC can be used just like a Yamaha FB-01 without the need for any software running on the host computer at all. Last time I saw the IMFC selling on Ebay, the price difference between...