Re: Is there any reason to install more than 1 MB RAM on a 286 PC?

Posted on 2023-10-07, 09:47

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I may have missed it but the original poster (OP) mentioned UMB as well. There is no restriction around the 286 and UMB. This is purely a software matter. I am running 128 KB of UMB on a PC XT, powered by an 8088! Well, there is a reason to connect to think of UMBs being a 386 thing, which is a …

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Re: Video Seven Vega Deluxe - SuperEGA (ish) card

Posted on 2023-10-07, 09:30

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by mkarcher

in Marvin \ Video

in Marvin \ Video

640x480 and 752x410 graphics modes (on multisync monitors that can do 25/29KHz) 60 row text modes (on multisync monitors) 120 and 132 column text modes (1080/ 1056 pixels wide), some of which work on regular CGA/MDA/EGA monitors! (15/18/21KHz) 640x480 Drivers for Autocad, Windows 2.0, Lotus 1-2-3 …

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Re: I disassembled an S3 Trio64 BIOS and am annotating it

Posted on 2023-10-06, 21:53

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by mkarcher

in Marvin \ Video

in Marvin \ Video

Would the beep function be for when the bios is told to print a bell character (ascii code 7) ? The function to output the bell character is Func0x2xe0. Beeps are also emitted during the POST, usually if the video memory test fails or no monitor is detected. You have PlayBeepPattern for that. You …

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Re: I disassembled an S3 Trio64 BIOS and am annotating it

Posted on 2023-10-06, 17:32

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

It also has a built in beep function, so could be that sometimes the beeps you hear are from the video BIOS and not the system BIOS. Speaking of the system BIOS, it apparently also has a stock int 10h handler. One of the first things this bootstrap code does is call into that handler. Later on it …

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Re: The Soundblaster DSP project

Posted on 2023-10-06, 16:54

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

4.16 is shorter then 4.13 - something is cutted. based on the reports here that CSP.SYS fails to load on AWE32 when the MCU is flashed with V4.16, I think best guess is the ASP code is removed from the V4.16 DSP - looking at 86box AWE32/ASP emulation code: https://github.com/86Box/86Box/blob/master …

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Re: Strange SIMM ram package

Posted on 2023-10-06, 16:51

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

unless thats what 6x Pericom PI5C 3861Q '10-Bit, 2-Port Bus Switch' chips are for? Pass signals thru resistors one way, enable transparent connection the other way? These kind of bus switch can in fact be used for voltage limitation. They use similar bus switches on late PCI graphics cards like the …

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Re: Is there any reason to install more than 1 MB RAM on a 286 PC?

Posted on 2023-10-05, 23:01

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Robbbert wrote on 2023-10-05, 22:25: After all, the slots wouldn't be there if they didn't do anything. "Creating demand for RAM modules" is also "doing something" 😉

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Re: SB2AWE EEPROM flasher utility.

Posted on 2023-10-05, 22:11

by

by mkarcher

in Marvin \ Sound

in Marvin \ Sound

I did not test the program much, but at first glance it was able write dump to sound cards CT2940 and CT4520. Thank you very much for making and publishing this program. It was easy enough to use that I was able to instruct someone via whatsapp how to revive his CT4390 AWE64 gold. It worked without …

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Re: UMC8881/8886 Datasheet

Posted on 2023-10-05, 17:25

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

VL pins, observed on the Gigabyte GA486IM 190 = /LGNT1 191 = /LGNT2 192 = /LREQ1 193 = /LREQ2 202 = /LRDY 203 = /LDEV On a VL-less board, I would expect pull-up resistors on both /LDEV and /LRDY. Obviously, 190-193 are multiplexed, being either parity pins or VL master control pins. I didn't find …

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Re: Where to obtain 110 MHz RAMDAC for ARK1000VL graphics card?

Posted on 2023-10-04, 18:40

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I tried the 4 possible combinations for R2 and R3, namely, R2, R3 open, 4.7K ------> default config 4.7K, 4.7K ------> garbage displayed (see image) 4.7K, open ------>blank screen, beeps open, open ------>blank screen, beeps So R3 open breaks the VL bus interface or disables the video BIOS. That's …

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Re: Where to obtain 110 MHz RAMDAC for ARK1000VL graphics card?

Posted on 2023-10-04, 06:00

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thank you very much for this level of detail. I'm sure others appreciate it as well. I will look into R2 and R3. If the configuration strapping has an internal pull-up (like 10K ) to set 80 MHz DAC mode, wouldn't we want this strap to go to GND via a 0-ohm resistor, or at least some resistor value …

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Re: UMC8881/8886 Datasheet

Posted on 2023-10-04, 05:42

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

59 = CA0 (first bank or only bank) 61 = CA0 (second bank) or CA1 (single bank) The way I number the cache address lines, there is no CA1 in dual-bank operation. Is the pin 61 typo? I have VCC on 61. Assuming it is pin 62. OK so it is similar to SiS496/7. Hmm if I have interlaved cache (dualbank), …

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Re: UMC8881/8886 Datasheet

Posted on 2023-10-03, 18:38

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

A recheck for CPU control signals and specially for cache would be appreciated (my board ATC-1415 has only one cache bank so I could not find control signals for the second one, also it has only 2 SIMM slots). Some CPU signals are routed through jumpers, so I could miss few. Thanks for writing up …

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Re: Is there any reason to install more than 1 MB RAM on a 286 PC?

Posted on 2023-10-03, 16:24

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

who needs EMM386 when you have EMM286 https://www.vogons.org/viewtopic.php?p=126345#p126345 :) 286 was EGA territory, nothing requiring VGA and more than 1MB would be playable with one exception being Windows. Indeed! But I didn't know about EMM286 until today! :D EMM286 is only useful in very …

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Re: Bypass write protection 5.25"

Posted on 2023-10-03, 15:32

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

pin 28 on ribbon cable, you can just cut it permanently pulling it high I don't think this will work on all drives. While it prevents the FDC from detecting that the disk is write protected, the drive still may ignore the write gate line if a write protected disk is inserted. I used to think that …

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Re: Setting the L2 to WT instead of WB, CY5x86

Posted on 2023-10-03, 15:26

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I fixed crash issue while switching that bit by issuing WBINVD command before patching it up. Sometime it still crash when I run other commands but if after, I run other tools that fill that cache like cachechk then it seam to get rid of the crashing issue. Usually, after reconfiguring the L2 cache …

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Re: Where to obtain 110 MHz RAMDAC for ARK1000VL graphics card?

Posted on 2023-10-03, 15:18

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm impressed with mkarcher's ability to view a 1 second video clip of a jittery image and determine the issue was too low of memory clock. Thanks for awarding me some extra nerd points :grinning: The clue is: The image contents are correct, but some lines are shifted (at least at some point) to …

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Re: Where to obtain 110 MHz RAMDAC for ARK1000VL graphics card?

Posted on 2023-10-02, 14:33

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It is possible that the written claim for 1280x1024x256c-60Hz was made in error or was made correctly, but not properly tested. I'm confident that 1280x1024x256c at 60Hz is possible with the ARK1000 chip. As we don't have all the required technical documentation, I don't know yet how this is …

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Re: Where to obtain 110 MHz RAMDAC for ARK1000VL graphics card?

Posted on 2023-10-01, 19:11

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

In viewing the ARK datasheet, it only mentions EDO support in the 2000PV; not the 1000VL or 1000PV. I might have mixed that up, sorry for the misdirection there. 1280x1024x256c @ 60 Hz, Vsync = 110 MHz (failed attempt, screen looks jittery, see previous video) According to the Bali32 manual …

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Re: Where to obtain 110 MHz RAMDAC for ARK1000VL graphics card?

Posted on 2023-10-01, 05:57

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Upon reviewing the manual for the ARK1000VL card again, it seems like no hackery should be required. In short, it mentions to insert the missing 256Kx16 memory modules, and have access to 1280x1024x256c. Which you do. Unless you use the patched BIOS, you just install the missing memory, and you get …

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