Re: Tiny Vortex86-based DOS gaming PC - weeCee

Posted on 2021-04-13, 23:35

by

by kdr

in Marvin \ System Specs

in Marvin \ System Specs

It works really well. Although the processor is 800MHz, the Vortex86 is much slower per clock than Intel processors, and can even be throttled in the bios for running speed-sensitive games : ... I'm gonna do a bunch more tests and benchmarks on it, but I have run it (and some other Vortex CPUs) …

---

Re: Mystery chip on Trident PCI graphic card

Posted on 2021-04-12, 23:23

by

by kdr

in Marvin \ Video

in Marvin \ Video

Try dumping the video BIOS while the card is in the PC and see if the checksum is correct. I'm sure you've already tried this, but quite often I can fix intermittent issues like this by thoroughly cleaning the gold fingers using isopropyl alcohol.

---

Re: Chossing an ISA graphics card

Posted on 2021-04-06, 08:54

by

by kdr

in Marvin \ Video

in Marvin \ Video

Nothing that you install in an ISA slot will come close to the performance of a VLB chip...

---

Re: (S)VGA 256-color shift and Chain 4

Posted on 2021-04-05, 07:25

by

by kdr

in PC Emulation

in PC Emulation

The CL-GD542x technical reference manual doesn't mention anything like that - whereas it does specifically call out a few situations where certain bits are either ignored or take priority. Here's what it has to say about GR05 bit 6 (256-color mode): Bit 6 (256-color Mode): If this bit is programmed …

---

Re: found a box full of ethernet cards. would like to know what to keep.

Posted on 2021-04-04, 01:50

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've got more PCI ethernet cards than I know what to do with, can hardly even give them away it seems.

---

Re: CRT monitor whine; what causes it, ways to mitigate it, do some display types suffer from it more than others?

Posted on 2021-04-02, 00:27

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yep, CGA hsync is 15.7khz and that is identical to what a standard television uses. You could try using an MDA monitor instead if you want to stick to something that's appropriate for the era: the hsync frequency is 18.4khz and could be just high enough to be inaudible for you and the kids. I find …

---

Re: What's the state of old PC networking?

Posted on 2021-03-29, 21:51

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Nearly all of my ISA network cards are 8-bit generics with 10base2 and AUI interfaces but no RJ45. For whatever reason, here in NZ it's been tough to find any Ethernet cards that are both ISA and have an RJ45. So I got my hands on an old 10baseT hub that had a 10base2 uplink port and built myself a …

---

Re: CGA Light Pen Showcase

Posted on 2021-03-25, 21:19

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Very cool! It's nice to see some "proof of life" that light pens were actually a thing... Note that some EGA cards also have a light pen header.

---

Re: Unknown Unisys 8-bit card, need help with identification

Posted on 2021-03-22, 21:20

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The board does not appear to have any ROM, so the drivers would need to upload some firmware into the card to make it functional. Could it be something similar to a 5250 emulation card? The IBM 5250 cards also have an onboard CPU/memory and use a 15-pin D sub connector with an adapter to interface …

---

Re: Resurrecting the IBM 5150

Posted on 2021-03-15, 10:24

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've done some further testing. In the Minimum Diagnostic Configuration (as above) with no cards, I get 1 long beep and 2 short beeps. With the CGA Card installed, and the dip switches reconfigured for CGA, I get 1 beep. I've also reinstalled the floppy drive and controller, and the drive seems to …

---

Re: Resurrecting the IBM 5150

Posted on 2021-03-14, 10:36

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

There's an excellent troubleshooting guide for the 5150/5160 at minuszerodegrees.net: http://www.minuszerodegrees.net/5150_5160/MDC/minimum_diag_config.htm If you think it's the CGA card that isn't working (a good guess) then I'd suggest trying a minimal configuration: just the motherboard and the …

---

Re: pls help to identify this VGA/EGA graphics card

Posted on 2021-03-12, 22:00

by

by kdr

in Marvin \ Video

in Marvin \ Video

As mkarcher says, it's probably an early CGA/EGA/VGA card with (some amount of) hardware emulation for CGA/EGA. The only unusual chip on the card (aside from the custom VTCL chip) is an LM339 quad differential comparator, which is probably used to convert the analogue RAMDAC output into the digital …

---

Re: 486 SX 16 & 20 MHz

Posted on 2021-03-08, 23:57

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Majority of DOS software only transfers 16bit at once when writing to VGA and also some of the most popular VL-Bus controllers, such as the omnipresent CL-GD542x series only had 16bit host interface anyway. So the 32bit nature of the bus is wasted unless using 32bit writes (likely GUI work). Even …

---

Re: Leading Edge CMC-1414BA - cut VGA cord repair

Posted on 2021-03-07, 20:57

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

From your description it sounds like the monitor might still work. There won't be any kind of on-screen display with an ancient VGA monitor like this one, so what you're seeing is consistent with the video cable not being connected to anything. If you're lucky the internal end of the VGA cable will …

---

Re: Require a 4:3 VGA and SVGA display solution

Posted on 2021-03-02, 22:47

by

by kdr

in Marvin \ Video

in Marvin \ Video

While I much prefer CRTs, for quick tests on the workbench I use an ancient Dell 15" LCD that's close enough to 4:3 aspect (1280x1024 - 5:4). It's only input port is analogue VGA. It has plenty of adjustments in the on-screen menu for getting the picture to look right and is ancient enough to have …

---

Re: Which operating systems work on i586?

Posted on 2021-02-26, 09:05

by

by kdr

in Marvin \ Software

in Marvin \ Software

Sphere478 wrote on 2021-02-26, 04:40: Do you have a condensed version I can add to OP which versions should someone try on a 586? Not really sure when exactly NetBSD became unusable on a 586, it'd take some work to narrow it down.

---

Re: Which operating systems work on i586?

Posted on 2021-02-25, 23:00

by

by kdr

in Marvin \ Software

in Marvin \ Software

"Of course it runs NetBSD" I'm pretty sure I was using NetBSD 1.5.x or 1.6.x (and maybe OpenBSD too) on AMD K6-2, but u know it has been almost 20 years... More recently I did some testing on virtual machines and NetBSD definitely seemed much easier on the hw requirement side than Linux, for …

---

Re: Cirrus Logic CL542X Vesa Local Bus graphics card

Posted on 2021-02-09, 09:35

by

by kdr

in Marvin \ Video

in Marvin \ Video

I doubt you'll ever figure out the card manufacturer. Cirrus Logic would happily supply the CL-GD542x chipset (along with schematics for a complete ISA or VLB card) to any OEM that wanted it. The resulting cards are all essentially identical; the only difference is the layout of the PCB and the …

---

Re: If we were to accept 15 years ago as retro....

Posted on 2021-02-07, 04:44

by

by kdr

in Milliways

in Milliways

I like to draw the line based on CPU socket: up to and including Super Socket 7 (for the most part) there was a "mix and match" style approach, with a variety of CPU manufacturers and chipset suppliers, all working together "seamlessly". Post-SS7 we're left with just AMD and Intel, and the common …

---

Re: 486 Motherboard missing PAL chip

Posted on 2020-11-17, 02:06

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Odds are the PAL would be an optional component that only needs to be fitted if you're using the Weitek co-processor socket. Probably just a bit of cheeky cost-cutting, given that the majority of users wouldn't need it. I doubt it's the reason your board won't boot. I'd suggest doing all the …

---