VOGONS


First post, by ychh0

User metadata
Rank Newbie
Rank
Newbie

During installation Windows98 with ATI Mach64 VLB 4MB, I found that default driver of Windows98SE support up to 1600*1200*16bit but ATI official driver 3.03 support only up to 1280*1024*24bit.

After checking informations around the internet, I found several sources about ATI Mach64 GX family, especially ATI Mach64 Graphics Pro Turbo 1600.

1. VOGONS WIKI
https://www.vogonswiki.com/index.php/ATI
- Graphics Pro Turbo 1600 (fast RAMDAC,PCI-only)

2. ATI Version 3.1 CD User’s Guide
http://www.vgamuseum.info/index.php/component … 2471f4373a9df1a
- There are three version of VRAM Mach64 variants ; ATI Graphics Pro Turbo 1600, ATI Graphics Pro Turbo and Winturbo
- 1600*1200 modes are supported by ATI Graphics Pro Turbo 1600 version only (Table 1)

3. Mach64 X Server Support
https://xjman.dsl.gr.jp/XF32/Mach64-1.html
- Each Mach64 VLB Variant use different ramdac.
1) ATI Graphics Pro Turbo/Winturbo : Normally ATI68860 or ATI68880
2) ATI Graphics Pro Turbo 1600 : IBM RGB514

I checked my VLB Winturbo and VLB Graphics Pro Turbo, it seems both equipped 68860. I have not seen any Mach64 with IBM RGB514 ramdac and wonder what’s the difference between those two ramdacs.

At first I thought I installed wrong windows driver , and after seeking some infos including aboves I guess 1280*1024 is original limit of driver of normal Graphics Pro Turbo. (According to VOGONS WIKI there is no Graphics Pro Turbo 1600 VLB) Windows98SE default driver may be the one that those two drivers are incorporated into.

Then could we infer ATI intentionally set resolution limit for Graphics Pro Turbo and actually two ramdacs have little difference ? Normal ATI Mach64 Graphics Pro Turbo using ATI68860 ramdac also has no problem in using 1600*1200*16bit?

I played around several hours with 1600*1200*16bit setting, there was no visible problem.

* Attached is my ATI Mach64 Graphics Pro Turbo 4MB VLB

Attachments

Reply 1 of 14, by mpe

User metadata
Rank Oldbie
Rank
Oldbie

As far as I know:

Winturbo = only 2MB VRAM (non upgradable). ATI RAMDAC
ATI Graphics Pro Turbo = upgradeable to 4MB VRAM, ATI68860 DAC @ 135 MHz
ATI Graphics Pro Turbo 1600 = upgradeable to 4MB VRAM, IBM RAMDAC @ 220 MHz

AFAIK the 1600 was PCI only. Your card is likely ATI Graphics Pro Turbo. Might be still running @ 1600*1200*16b but likely at non-VESA compliant refresh rate. This was in CRT era and a quality RAMDAC was a big deal back then. Other vendors were releasing 220 MHz versions of their cards too.

Blog||486DX-50|NexGen 586|S4

Reply 2 of 14, by blurks

User metadata
Rank Oldbie
Rank
Oldbie

ATI advertised the 1600x1200 mode as "PCI version only" (see attached ad). Although there seems to be no technical reasoning for this restriction as the VL bus is able to keep up with the continuous data stream.

I have the the PCI version in box which explicitly states that it comes with 1600x1200 support. It also has the Spectra DAC (ATI68860)

ad.jpg
Filename
ad.jpg
File size
98.06 KiB
Views
247 views
File license
CC-BY-4.0

Reply 3 of 14, by Anonymous Coward

User metadata
Rank l33t
Rank
l33t

I'm pretty sure the 1600 is PCI only. If a VLB version exists I have never even seen a photo of one.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 4 of 14, by derSammler

User metadata
Rank l33t
Rank
l33t

Wasn't his point that his card can do 1600*1200 and appears to be a 1600 VLB, even though it clearly isn't? So the 1600*1200 was just something ATI controlled in their drivers and not really hardware-related.

http://retro-net.de/blog.html

Reply 6 of 14, by kixs

User metadata
Rank l33t
Rank
l33t

I've tested my Mach64 4MB VLB and it does 1600x1200/16-bit at 54Hz on a CRT monitor. Diamond S3 968 4MB VLB does the same at max 67Hz - but the CRT might be the limit here as I'm using EIZO FlexScan T563 17" at the moment.

My Amibay: SALE | BUY - Updated on 2020-05-25

Reply 7 of 14, by derSammler

User metadata
Rank l33t
Rank
l33t
Unknown_K wrote on 2020-03-25, 10:42:

1600x1200@60hz needs around 173hz RAMDAC

No one said 60 Hz. And most cards at that time could do their highest resolution in interlaced mode only anyway, which would not need a RAMDAC faster than 90 MHz.

http://retro-net.de/blog.html

Reply 8 of 14, by mpe

User metadata
Rank Oldbie
Rank
Oldbie

The ATI Graphics Pro Turbo 1600 was launched mid-1995. At that point VL-Bus was well out of fashion. Most likely they launched 1600 only for PCI.

The 1600x1200 @75 is not the only benefit of the 220 MHz RAMDAC. It can do higher refresh rates at lower resolutions too.

But the designations were purely marketing and later in Mach64 life they were clearly mixing and matching features as they needed.

I have a Mach64GX PCI card with IBM RAMDAC, factory "Non-upgradeable" sticker on the back, upgrade pins header still present and 512kx16 1-cycle EDO VRAM chips (thus incompatible with standard 8-chip VRAM upgrade modules).

Is it WinTurbo (because of "non-upgradeable" sticker), or 1600 because of the IBM RAMDAC?

Blog||486DX-50|NexGen 586|S4

Reply 9 of 14, by blurks

User metadata
Rank Oldbie
Rank
Oldbie
mpe wrote on 2020-03-25, 11:28:

I have a Mach64GX PCI card with IBM RAMDAC, factory "Non-upgradeable" sticker on the back, upgrade pins header still present and 512kx16 1-cycle EDO VRAM chips (thus incompatible with standard 8-chip VRAM upgrade modules).

Is it WinTurbo (because of "non-upgradeable" sticker), or 1600 because of the IBM RAMDAC?

Technically it could be Graphics Pro Turbo 1600. Maybe yours was a GPT surplus stock that went into the OEM market relabeled. If you ever decide on trying an upgrade module: mine has the number PN 109-31600-00.

mpe wrote on 2020-03-25, 07:41:

Winturbo = only 2MB VRAM (non upgradable). ATI RAMDAC
ATI Graphics Pro Turbo = upgradeable to 4MB VRAM, ATI68860 DAC @ 135 MHz
ATI Graphics Pro Turbo 1600 = upgradeable to 4MB VRAM, IBM RAMDAC @ 220 MHz

The 1600 I have comes with ATI's Spectra DAC ATI68860. There were probably different revisions. I also know of Texas Instruments RAMDAC's being used for the Mach64 lineup.

1.jpg
Filename
1.jpg
File size
140.26 KiB
Views
175 views
File license
CC-BY-4.0
2.JPG
Filename
2.JPG
File size
177.89 KiB
Views
175 views
File license
CC-BY-4.0
Last edited by blurks on 2020-03-25, 13:53. Edited 4 times in total.

Reply 10 of 14, by Anonymous Coward

User metadata
Rank l33t
Rank
l33t

It's entirely possible that ATi offered more than one RAMDAC on the 1600, but I highly doubt the ATi RAMDAC runs at 135MHz on your card, it's probably something comparable to the IBM RAMDAC. Is the standard Mach64 really only 135? For some reason I thought it was a 170.

I also didn't know EDO VRAM was used on the Mach64s. Perhaps the 31600 upgrade module uses EDO VRAM and the 26400 module uses regular VRAM? That might explain why more than one module exists.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 11 of 14, by blurks

User metadata
Rank Oldbie
Rank
Oldbie

Interestingly, this site backs mpe's statement concerning the RAMDAC which I find weird, as I have a 1600 with a regular SpectraDAC lying in front of me. ATI probably stepped up their game and developed a new revision of the 68860 with higher clocks?

Reply 12 of 14, by mpe

User metadata
Rank Oldbie
Rank
Oldbie

The box clearly says GPT1600 indeed.

However, ATI68860 is the part from regular Winturbo/Pro Turbo and I have it on several non-1600 Mach64GX cards. Are you sure it is actually 220 MHz DAC and it is the card that was shipped in that box? Does it support 1600x1200 @ 75 Hz? Another thing that in manual they claim the only card to support DDC1 is the 1600.

This article from PCM clearly shows GPT1600 with IBM DAC:

Screenshot 2020-03-25 at 13.41.48.png
Filename
Screenshot 2020-03-25 at 13.41.48.png
File size
303.34 KiB
Views
149 views
File license
Public domain

But as you said it could be they launched with IBM and scaled up their own DAC later.

Blog||486DX-50|NexGen 586|S4

Reply 13 of 14, by blurks

User metadata
Rank Oldbie
Rank
Oldbie

I stumbled across this article during my research aswell but the photo seems to show just a promo picture for the press. I'm pretty certain mine is the original that was shipped in the box as it would make no sense to replace a GPT with a GPT 1600. Both cards were hugely expensive around 1995/1996 and the benefits of this upgrade path were marginal. I also need to add that my example is a very early one (early 1995) with Windows 95 compatibility advertisement so a late revision 68860 could be out of question.

PC Mag (Dec 95 issue) also claims the Spectra DAC has 135 MHz while RGB from Amoretro says it is a 200 MHz RAMDAC. The truth must be somewhere along those lines.

Reply 14 of 14, by ychh0

User metadata
Rank Newbie
Rank
Newbie

I just tested my Graphics Pro Turbo VLB with Windows 98SE default driver. It displays up to 1600*1200*16bit at 54Hz.

* This monitor is small 12in. LCD monitor. I use this for simple testing because it is handy and capable of display 15kHz.

Attachments