Re: Best PCI sound card to work on DOS natively

Posted on 2022-01-28, 23:21

by

by mkarcher

in Marvin \ Sound

in Marvin \ Sound

I tested a couple of sound cards in a 440BX mainboard, a MSI MS-6163. I limited testing to cards that support hardware-assisted ISA DMA emulation (that is no need to use EMM386 / DSDMA). The results match the consensus in the retro community: The best DOS compatibility was provded by the ESS Solo1 …

---

Re: 32Kx8 sockets on 486 motherboard

Posted on 2022-01-26, 15:27

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

A google search turns up chips which look like they'd fit available from mouser.co.uk. Is this likely to be the right stuff, are they really still in production? In case you are talking about the IDT 71256SA series chips at mouser, they should work. 15ns would leave more room for good timings bus …

---

Re: 10 pin 44256 chips

Posted on 2022-01-25, 22:46

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

4 of them is 1MB, so it's going to be 1MB to 2MB - the difference: 1MB tops out at 640x480 truecolour, 800x600 64k colour, 1024x768 256 colour 2Mb ups the last two to truecolour and 64k Nope, 4 of them is 512KB. One of these chips only has half a byte (4 bits) on 256K addresses, so you need two of …

---

Re: 10 pin 44256 chips

Posted on 2022-01-25, 14:54

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

While the number of the chip nicht vary from manufacturer to manufacturer, these chips are very common. Any fast page mode 256k x 4 DRAM chips in 20-pin DIP case will do, these chips are generally interchangable. I guess four similar chips, possibly as SMD chips, are already present in close …

---

Re: Schneider Euro PC

Posted on 2022-01-24, 22:17

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

In this German training manual it states that the Joystick port in EuroPC 1 is Digital. It also states the joystick 1 is reached at address 258h. If i am not mistaken the analog PC Joystick port is address 201h. - Read more at: https://www.epanorama.net/documents/joystick/pc_joystick.html So i …

---

Re: DOS Text Scrolling Crash using Trident TVGA9000i-3 on 8-bit 8088 based PC

Posted on 2022-01-24, 22:11

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

The UMA (0xA0000–0xFFFFF which is 640KB to 1 MB) is not mapped to RAM chips, so if any chip in the bus want to use this space it can. The software just need to read or write there to program the chips reading there (that maybe chip registers or on board expansion memory I think). That is why it is …

---

Re: Can an EGA card produce a double-scanned video signal?

Posted on 2022-01-24, 21:29

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

24 refers to the clock speed in Mhz, not the horizontal scan rate in Khz. But perhaps you're right that some EGA cards have this ability. This 24Mhz is really close to to the typical 25Mhz VGA pixel frequency. OK, I stand corrected. 24kHz horizontal sounded quite low for 400 visible scan lines, so …

---

Re: DOS Text Scrolling Crash using Trident TVGA9000i-3 on 8-bit 8088 based PC

Posted on 2022-01-22, 21:45

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

Glad you have resolved your issue. Your XTjr project is very interesting. I never used a computer with less than 1 MB of RAM but I don't understand how a PC with less than 640 KB of RAM can work with cards that have an embedded BIOS as the reserved address space for the BIOSes is in the UMA. If a …

---

Re: Can an EGA card produce a double-scanned video signal?

Posted on 2022-01-22, 10:39

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

Have a look at This post on vcfed: The card seems to support a "24kHz mode", which might very well be double-scanned 200 lines, which can be enabled by a jumper. Your monitor is perfectly able to sync on 400 visible scanlines at 24kHz.

---

Re: Sound Blaster AWE32 Supports 30-pin EDO RAM (up to 16MB x2)

Posted on 2022-01-17, 23:55

by

by mkarcher

in Marvin \ Sound

in Marvin \ Sound

Actually, while I don't think the AWE32 was designed with EDO RAM in mind, it's not that surprising that it works with EDO RAM. EDO and FPM only behave significantly different if you are actually keeping pages open for more than a single access or a single burst. Controllers designed for FPM RAM …

---

Re: Alloy on CPU pins

Posted on 2022-01-17, 18:41

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Will try. Do I need additional flux or there is enough one that is on wick? If you are lucky the flux on the wick is sufficient. Flux also acts as thermal transfer agent (like heatsink compound), helping to get the pins hot enough so the solder melts faster and flows into the wick. So even if you …

---

Re: 486 L2: Comparison between Write-Through & Write-Back (with and without dirty tag ram)

Posted on 2022-01-16, 18:01

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

WT / WB with or without tag is all about trade-offs. The CPUs is less blocked by memory writes.The cost we have to pay for this is (apart from implementation complexity) is extra time for certain reads (whenever a reading operation triggers a write back cycle). Chances are that for typical software …

---

Re: 486 L2: Comparison between Write-Through & Write-Back (with and without dirty tag ram)

Posted on 2022-01-15, 20:52

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

These post should help you diagnose poor memory performance on 486 boards. For general use, a configuration is preferable in which the complete memory is cacheable in L2 cache, and the L2 cache operates in write-back mode with a "dirty tag bit". On modern 486 chipsets (like the UMC 8881 or the SiS …

---

Re: 486 L2: Comparison between Write-Through & Write-Back (with and without dirty tag ram)

Posted on 2022-01-15, 19:37

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've taken similar measurements on a Gigabyte GA486IM. That board uses the same UMC chipset (UM8881/UM8886) as the famous Biostar 8433UUD. To highlight the differences between the memory throughput of the boards, I also used a AMD 486DX4 with L1 cache set to write-through. L2 write-back with dirty …

---

Re: ASUS PCI/I-486SP3G Onboard IDE Problem

Posted on 2022-01-10, 12:40

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It is just counting up the ram during post 4-5 times now, but no big deal for me. (512 KB cache) I think it wouldn't make such a big difference anyways would it? If the BIOS counts the memory multiple times, it seems like "Advanced BIOS setup" / "Quick POST" is disabled. The extra cache won't make …

---

Re: Does Intel 815(EP) support single-sided PC133?

Posted on 2022-01-09, 22:09

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The issue isn't single vs double sided, it's chip density. Because vendors felt that was too difficult for people to get their heads around, there was a lot of confusion spread around over sidedness. Actually it's not so complicated. A DIMM is made up of a given number of chips, each with a certain …

---

Re: Q: EDO vs. FPM - how to tell which is which

Posted on 2022-01-09, 20:47

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Of the most common modules, -70 is likely to be FPM and -60 is likely to be EDO There may well be FPM chips that are faster then 70nS (but rare), and pretty sure EDO was never in 70nS specification I have a lot of 60ns FPM memory. I estimate the FPM-to-EDO ratio of 60ns PS/2 SIMMs is around 50:50 …

---

Re: ASUS PCI/I-486SP3G Onboard IDE Problem

Posted on 2022-01-09, 20:38

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Unfortunately I don't have any PCI IDE controllers (yet) Don't expect PCI IDE controllers to be easy on early 486 PCI boards. I didn't try them on the PCI/I-486SP3G yet, but the experience wih UMC8881-based and SiS496-based boards is not good. I got a Highpoint-based controller work on the Shuttle …

---

Re: 16 bit ISA voltage testing normals

Posted on 2022-01-09, 13:44

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You can not find out whether a board could damage a card by voltage measurement alone. But voltage measurement can raise red flags: The supply pins should all be near their nominal voltage. No pin except for the supply pins is allowed to be below 0V or above 5.1V. The clock and OSC pin must be …

---

Re: 16 bit ISA voltage testing normals

Posted on 2022-01-09, 10:57

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

A14 to A20 are address pins. During an ISA cycle, they indicate what address is accessed. When no ISA cycle is active, the voltage of those pins doesn't matter, and depends on the mainboard. The only pins that contain supply voltage are B1 (GND), B3 (+5V), B5 (-5V), B7 (-12V), B9 (+12V), B10 (GND), …

---