Re: How to maximize Upper Memory on 440BX?

Posted on 2017-07-26, 10:05

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Are there any messages about UMBPCI when it is started? What about when using "EMM386.EXE RAM" in config.sys and make it print extra info when it starts (by putting VERBOSE as parameter or pressing ALT when DOS is loading)? Sure, extra RAID/IDE controllers with their BIOSes will take away UMB, as …

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Re: How to maximize Upper Memory on 440BX?

Posted on 2017-07-26, 06:49

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

How much UMBs you expect, would like to have, or need? Just quick calculations: From the first megabyte available in real mode, you get 640kb of RAM and 384kb for other purposes. In that 384kb area some is reserved for expansion cards and system roms, so quickly calculated 128kb for video ram (to be …

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Re: Thinking of modifying my rig

Posted on 2017-07-26, 05:59

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Anyway... first thing I'm wondering is if I should replace the sound card with an AWE64. Would I get any noticable improvement in either DOS or Windows? Some topics I've read seem to indicate that the AWE32 and AWE64 are basically just SB16s with more stuff attached and I've even heard rumblings …

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Re: IDE SSD incompatible with laptop

Posted on 2017-07-25, 21:53

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes, do verify that the SSD works on other computers as expected. But frankly put putting a 128GB drive in place of 12GB drive into an old machine can cause problems. If the new drive were 32GB there is more chance for it to work, some BIOSes have issues with drives larger than about 32GB. Some hard …

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Re: IDE SSD incompatible with laptop

Posted on 2017-07-25, 20:11

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Why leave out the details? So, incompatible in what way? Please describe your observations. How big drive it had before, and how big SSD drive you bought for it? What are you installing on it? Yes sometimes BIOS can't handle too large drives and hang the system or show smaller drive.

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Re: Found a Unique 286, need a unique power supply for it

Posted on 2017-07-25, 20:00

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

If nothing else looks broken, one common point of failure is a high-valued resistor (often largish in size too) that feeds the switching controller from the main bulk cap before the switching starts and can provide power to it.

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Re: OPL2LPT

Posted on 2017-07-25, 06:10

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

There is also the possibility of finding a USB parallel port that is up to the task I highly doubt this unless it's a very special USB parallel adapter with very special drivers and very special API to use it. My experience with USB parallel ports is that they are only suitable for connecting …

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Re: CGA timings (again)

Posted on 2017-07-25, 05:52

by

by Jepael

in PC Emulation

in PC Emulation

Yes because it needs the same horizontal line rate. I think based on what SarahWalker it's 57 characters total instead of 114 characters total so that's 57*8 == 912/2. So new pixel data is sent every other clock so in essence pixels are double as wide so there can be half the pixels on screen when …

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Re: CGA timings (again)

Posted on 2017-07-24, 21:49

by

by Jepael

in PC Emulation

in PC Emulation

Modern devices use 27 MHz crystal to get 13.5 MHz for sampling PAL and NTSC, and as NTSC line is 858 pixels wide, Oh, interesting - I had wondered where the 13.5MHz sample rate came from, being neither a nice multiple of the NTSC color carrier frequency nor giving square pixels. The fact that it …

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Re: OPL2LPT

Posted on 2017-07-24, 20:53

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

I hope you did not clone the awkward crystal oscillator circuitry for this :) Meanwhile, the interrupt pin of OPL could be connected to LPT interrupt pin, maybe even through a jumper so it can be removed. I'm happy to do a schematic review if you like. I can also try to mod some existing programs to …

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Re: CGA timings (again)

Posted on 2017-07-24, 19:52

by

by Jepael

in PC Emulation

in PC Emulation

I've used 315/88 MHz for the color carrier, so that's 315/22 MHz for the crystal frequency (157.5MHz/11 is just as good of course). It's really not just 14.31818 MHz as written on crystals. Modern devices use 27 MHz crystal to get 13.5 MHz for sampling PAL and NTSC, and as NTSC line is 858 pixels …

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Re: How reliable compact flash is?

Posted on 2017-07-22, 18:07

by

by Jepael

in Milliways

in Milliways

SD does not have any logic, its a dumb medium that if written to the same block many times over will die pretty soon; how did You check that it is not the FS that died here, but the medium is indeed unreliable? SD cards DO have wear leveling, the exact implementation is manufacturer specific though …

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Re: K6-III+ 450 embedded woes

Posted on 2017-07-20, 09:54

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Most likely you have 66MHz FSB and 5x multiplier, but it's possible the CPU speed is detected wrong as well if the BIOS does not support such new model CPU. To get 450MHz, you should set 100MHz FSB and 4.5x multiplier, but you also need 100MHz compatible memory (PC100). If you don't have 100MHz …

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Re: OPL2 songs : Looking for DRO files

Posted on 2017-07-19, 21:58

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

Did you look at VGMPF yet? Does it have to be .DRO, or would similar recordings like RDOS .RAW or .IMF suffice? back2roots site had a package called cta-adlib.zip, maybe found elsewhere these days. I have personal preference order of .RAW, .VGM, .DRO, .IMF because of timing granularity, but that's …

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Re: Diamond EDGE 3240 PC game/midi port pinout

Posted on 2017-07-19, 21:22

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Network cables have 8p8c connectors, it looks like you need 10p10c connector. I don't know if it has MIDI pins, as for two standard joysticks or one special joystick you need all 10 pins (4 pots, 4 buttons, supply and ground).

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Re: Wireing an AT psu power switch?

Posted on 2017-07-19, 20:47

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

First measure which two wires go to power input socket. Then you at least know which two wires not to connect together. Most likely it does not matter which way to send the power to the remaining two wires. After all, in many countries you can connect the AC plug to wall which way you like. Also the …

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Re: Flashing HW/SW: Dediprog vs Aardvark

Posted on 2017-07-19, 20:37

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I don't know about Dediprog, but can say a few things about Aardvark. Pros: -Works in windows and linux -kind of just works -good for commanding SPI and I2C devices with PC, not just memory programming -separate memory programming tool for easy memory programming Cons: -not quite hobbyist price - …

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Re: Problem enabling mouse under DOS 6.22

Posted on 2017-07-18, 07:32

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Just to be sure, is it a PS/2 mouse with a 6-pin mini-DIN connector, or serial mouse with a 9-pin DSUB connector? IIRC, mouse drivers did not come with DOS but the mouse, so you may have an incompatible driver for your mouse. If it's a PS/2 mouse, make sure your mouse driver can work with PS/2 mice. …

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Re: Finding bugs in 8086-80386 emulation core?

Posted on 2017-07-17, 21:31

by

by Jepael

in PC Emulation

in PC Emulation

So do you correctly handle size override prefixes (66)? For example, it's 16-bit code, so all data and address sizes are 16-bit unless data/address size overrides are used. 6a XX : push imm8 as 16-bit word 66 6a XX : push imm8 as 32-bit doubleword

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Re: MPU-401/Compatible UART-mode Buffer Reference

Posted on 2017-07-15, 23:36

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

Validating the UART-mode transmit buffer of an actual MPU-401 or variant yet needs to occur, as it's more-or-less the reference standard, but remains mostly anecdotal at 256-bytes until it can be tested, or determined through ROM disassembly otherwise. From manual: UART mode 85 bytes for firmware …

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