Re: Unknown ISA BOOT Card

Posted on 2023-07-29, 06:32

by

by jmarsh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The KM681000BL chips are 128K SRAM (x4 = 512K total), and they're -L variants with low standby current (probably preserved by the battery) so those are probably used for a static ramdisk. Which I guess doesn't really make it a ramdisk at all.

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Re: Information on 'imaging' a hard drive, please.

Posted on 2023-07-23, 21:18

by

by jmarsh

in Milliways

in Milliways

I didn't know the 360 could only use proprietary hard drives (thanks Microsoft). Can I at least make a disc image from the 360's hard drive (now that it has all of the games on it that I want), and then if the hard drive becomes corrupted, then I can put the disc image back on the hard drive to …

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Re: Information on 'imaging' a hard drive, please.

Posted on 2023-07-20, 04:14

by

by jmarsh

in Milliways

in Milliways

IIRC the xbox 360 requires a specific type of drive with custom firmware, you can't just clone the data to any old SATA drive and expect it to work.

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Re: New to retro x86. 486DLC cache/A20 issues on mysterious mobo variant.

Posted on 2023-07-18, 04:25

by

by jmarsh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I think A20M# should be connected to the keyboard controller (A20 gate). It's so the CPU's internal cache knows whether or not to pay attention to the A20 address line. It doesn't affect the 386 because that has no internal cache.

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Re: How relevant is SSE context switching for DOS?

Posted on 2023-07-16, 12:34

by

by jmarsh

in DOS

in DOS

DOS isn't a multitasking OS though - it has no concept of context switching full stop, let alone things like FPU/MMX and SSE state.

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Re: How relevant is SSE context switching for DOS?

Posted on 2023-07-16, 11:42

by

by jmarsh

in DOS

in DOS

If any TSR wanted to use them, it would have to be responsible for saving the original contents and restoring them when returning. It's the only sane way it would work.

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Re: Incorrect CPU speed information displayed by Chess System Tal

Posted on 2023-07-11, 12:19

by

by jmarsh

in DOSBox Games/Apps

in DOSBox Games/Apps

Not sure what "bug" you're referring to here. DOSBox is an emulator, the CPU it implements will have much lower performance than your real one.

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Re: Capacity of standard CD and CD-R

Posted on 2023-07-08, 07:44

by

by jmarsh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

A "standard" CD is 74 minutes long. Each minute has 60 seconds. Each second consists of 75 frames (aka sectors). Each frame holds 2048 bytes of data (in Mode 1 format). 74 * 60 * 75 * 2048 = 681,984,000 bytes total data.

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Re: 5v on Socket 7 motherboard

Posted on 2023-07-05, 04:26

by

by jmarsh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

If the voltage is drooping and the plug is hot (= lots of current being pulled through it) something has probably shorted or very close to it. Disconnect the PSU, measure resistance between 5V and GND on the motherboard.

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Re: PicoGUS: ISA sound card emulator with Raspberry Pi Pico (Gravis Ultrasound, AdLib, MPU-401, Tandy, CMS)

Posted on 2023-07-02, 12:11

by

by jmarsh

in Marvin \ Sound

in Marvin \ Sound

PSRAM on the Teensy 4.1 defaults to 88MHz. You can push it higher, the PSRAM chip says it can run at up to 133MHz but mine only works up to 120MHz. There must be some decent overhead though because unlike the latter thread suggests, it's not even fast enough to handle 640x480x60Hz using 4-bit colors …

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Re: Descent runs far too fast in FreeDOS

Posted on 2023-06-28, 22:18

by

by jmarsh

in Marvin \ Software

in Marvin \ Software

descent -640x480 Runs the game in "hi res" 640x480 mode which runs at a more reasonable speed on faster PCs. You do lose the cockpit overlay display mode though.

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Re: Hitman Contracts won't launch on Windows 10

Posted on 2023-06-25, 19:09

by

by jmarsh

in Windows

in Windows

Exception Info 8 indicates a DEP violation, try disabling DEP for HitmanContracts.exe.

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Re: serial mouse not detected on a 386 motherboard

Posted on 2023-06-20, 17:16

by

by jmarsh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So that post, since older mice you had to hold a button to set Mouse Systems mode, makes me think that one of the control lines DSR or DTR or one of those is stuck. Unlikely. Drivers that auto-detect the mode will use MS mode if the mouse identifies itself as such, otherwise they use mouse systems …

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Re: CD Switch Not Recognised In-Game (Game is the original C&C)

Posted on 2023-06-15, 16:53

by

by jmarsh

in DOSBox Games/Apps

in DOSBox Games/Apps

I am going to guess-blame this on the CD drivers, as I never faced such issues back in the old days. Today I use UDVD2 driver for my slot-feeding DVD drive on the Pentium MMX. If I go back to something more standard (e.g. OAK driver) perhaps it would fix this issue? DOSBox doesn't use any hardware …

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Re: Is there any progress on 3dfx emulation?

Posted on 2023-06-15, 06:16

by

by jmarsh

in Windows

in Windows

Right, so what about using a type of hal instead of full-on software emulation? One does not simply "use a HAL." Especially if they want code to be portable. If the system it is being run on is x86, then not everything should need to be emulated. The problem is you can't selectively emulate some …

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Re: Is there any progress on 3dfx emulation?

Posted on 2023-06-14, 13:51

by

by jmarsh

in Windows

in Windows

You can't exactly run a CPU in real mode (with full access to segment registers, page tables etc.) from within a program. Not to mention on systems that aren't x86...

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Re: Is there any progress on 3dfx emulation?

Posted on 2023-06-14, 12:04

by

by jmarsh

in Windows

in Windows

There are problems with both 3dfx and win9x emulation in DOSBox that both boil down to how floating point is handled, the only way it would ever be properly portable would be if someone wrote full x87 emulation code and I don't think that's ever been done for any project.

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Re: Edsun CEG (Continious Edge Graphics) RAM DAC

Posted on 2023-06-07, 02:10

by

by jmarsh

in Marvin \ Video

in Marvin \ Video

At the very least it should act as a normal 8-bit color RAMDAC if it is truly a drop in replacement. To get the Anti Aliasing features, you need to include that logic in your graphics code. Too bad it is not automatic, but we are talking 1990 technology after all:) The ebay listings say they're …

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Re: XTA to ATA bridge: is it possible?

Posted on 2023-06-02, 19:59

by

by jmarsh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

There is no need. Connect them to an 8-bit controller like they were designed for, then plug that controller into any ISA slot. The card's BIOS will hande the rest.

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Re: ISA Blaster: A software-defined ISA Card

Posted on 2023-06-01, 08:46

by

by jmarsh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Disagree, because in that case you still need a separate floppy controller which defeats the purpose of the proposed "all in one" card. And that code is hardly portable to generic hardware...

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