PS: In the first book, you can also find this gem, misspelling the VOGONS Wiki. Filename image003.jpg File size 83.39 KiB Views 417 views

I had a (albeit rather brief up to now) look at the first volume The History of the GPU - Steps to Invention , as I have access to a library subscribing to Springer's ebooks. I like John Peddie's Chasing Pixel columns published on the IEEE Computer Society's website. The chapters that I read in the …

If the graphics card manufacturer took advantage of the additional clock select pins – like on the card that started this thread – he could easily have the card select between more than the usual 8 pixel-clock frequencies. For the end user: If the video BIOS and/or driver knows about this, this can …

PS: I forgot to mention: In the newer ET4000 (TC6100AF), the newly added, undocumented CRTC register 0x31 seems to work exactly as on the later ET4000W32i. As described, bits 6-7 control the clock select lines. Bits 4-5 are not implemented and always read back as 0. Bits 0-3 can be written and read, …

Best guess: Same type of chips as already on there: µPD424210-60-G. Currently, the card has 1 MiB of memory. By adding an extra 1 MiB, you "unlock" the resolutions that require more than 1 MiB. For example: 800x600x24 bpp (truecolor) or 1280x1024x256, etc.

I got to test an the older revision of the ET4000, marked TC6058AF. In that revision, the chip behaves as described in the 1990 data book: Pins 12 and 109 act as output enable for the video RAM, CRTC register 0x31 does not exist. I.e., it always reads back as zero, regardless of what you write to it …

To be clear: I merely used the citation from the IBM document as evidence that a newer data book exists for the ET4000; newer than the 1990 edition that is on Bitsavers and archive.org. This thread is still about an ISA card.

There is (in an IBM PS/2 document) a reference to a newer ET4000 data book, dated 1992. But no one seems to have scanned it? Filename databook.png File size 12.19 KiB Views 1020 views

The video BIOS contains code to set bits 6-7 of CRTC register 0x31. See part of it in the following Ghidra disassembly. The clock select value to be programmed is in CH. Then it puts one bit into the (documented) "clock-select 2" bit of CRTC register 0x34, and the rest into CRTC register 0x31: …

Spurred by another forum, I looked at an ET4000-based ISA graphics card (unbranded, PN 9201 Rev A ) with one particular oddity: Pin 12 of the ET4000 (TC6100AF, in its usual 144-pin package) was connected to a clock selection pin on the clock generator IC. According to the publicly available data …

Ultrax wrote: Also, what computer did you put it in? Just curious as I thought only x86 machines had ISA. 😀 An Atari TT. There are boards to convert the VMEbus used in that machine to ISA. Some Atari clones even had native ISA slots. Works very well with graphic and network cards.

First: let me preface a) that I don't know with certainty what happened and b) that you probably won't be able to reproduces this with a PC, so you're safe. Now to the technical details: with the computer I put this card in, I can separately control the RESET line of the ISA bus. So, I thought, …

Never mind. I killed the sound card while trying to make it work properly. :depressed: Well, another OPL3 chip that goes into electronic waste then. Yet, if you know the answer to my original question, feel free to post it. Maybe someone else will find the thread in the future and will have a …

Hello, I'm trying to get a Soundblaster 16 with a Vibra16S chip and an OPL3 (CT-2800, ISA non-PnP) to work properly in the ISA slot of a non-MSDOS-based system. (In fact, it's not even x86 architecture.) Anyway, it works fine so far; I can configure interrupt, DMA channels, MPU port number, set the …