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Re: Copam U-series 486

Posted on 2021-07-19, 06:25

Headland datasheet did not help. I tried a few things with DOS debug but nothing helped. So I think hardware is ready for now. I'll try another RAMDAC if I find one. But for now I think this computer is finally ready. But one more thing about the RAMDAC issue. I should have tested again with the DX2 …

Re: Copam U-series 486

Posted on 2021-07-16, 17:19

I got the port trapping somewhat fixed. Meaning colors are better like when no trapping at all, so colors are not quite correct on the problematic games. I think the problem was that there is some time frame to output all red, green an blue values and that was not met when trapping ports and …

Re: Copam U-series 486

Posted on 2021-07-14, 16:25

I'm actually trying to code such TSR but no luck so far... I can trap the ports and non-problematic games continue to work fine. But the problematic games now have even more wrong colors even when internal cache is disabled! Results are the same even when I don't do anything in the EMM386 handler …

Re: Copam U-series 486

Posted on 2021-07-14, 04:56

I did a little more testing last night. Color problems are gone when CPU is set to 16 MHz but they appear again at 20 MHz. I could modify the switch at the back of the computer to 16 / 33 MHz (change of two jumpers is needed instead of one). 16 MHz is faster than 33 MHz with internal cache disabled. …

Re: Copam U-series 486

Posted on 2021-07-13, 16:37

New RAMDAC arrived, or actually 16-bit Tandy VGA card with WD90C30-LR controller. It is no wonder similar card performs so well on my 286 because it is fast, just as fast as CL-GD5426. I didn't expect it to be that fast. I updated results to the spreadsheet. WD controller is older, maybe one year or …

Re: WP32 McCake : MT32 compatible waveblaster board

Posted on 2021-07-13, 10:32

not sure if there are any differences in the recording itself, but for my ears the DB50XG sound is in a completely different, better, league. I too think that DB50XG is the best of them but the Phoenix soundfont is a good alternative for real Yamaha. I tested the Phoenix soundfont more with some GM …

Re: WP32 McCake : MT32 compatible waveblaster board

Posted on 2021-07-12, 11:02

I didn't have enough time for testing last weekend but I'm really impressed so far. MT-32 emulation sure sounds nice and I really like how easy it is to change modes with mt32-pi command line utility. Soundfont support is very nice also so this one little internal MIDI-device really does it all. I'm …

Re: Copam U-series 486

Posted on 2021-07-06, 09:40

I was last of the early birds to get McCake. It arrived yesterday. Fully MT-32 compatible MIDI daughter board is quite unbelievable. And it supports soundfonts as well. I didn't have time to test it yet but I'll try to do so today. It should be an excellent board for any MS-DOS gaming system, Copam …

Re: Copam U-series 486

Posted on 2021-07-03, 09:43

I must have had back luck then. Slow card have worked but 1993 cards have not. I've tested one CL-GD5422 based card and it did not work but worked on a 386 and 486. The #9 S3 928 I already tested on Copam did not work on my 286. Then there was one Ati 28800-5 based ICL card but again, it did not …

Re: Midi help - SCC-1 + CM64

Posted on 2021-07-03, 06:04

I recommend to avoid line-in on old Sound Blasters. It can reduce the quality a lot. There are alternatives to using external mixer. I like to use Creative Gigaworks T20 and T40 speakers because you can connect two devices to them at the same time. You only have one common volume control but it has …

Re: Copam U-series 486

Posted on 2021-07-03, 05:46

New RAMDAC is now on its way. Actually I found a whole ISA card based on WD90C30-LR controller. It is very good, actually. And not only that, this card has RAMDAC already on a socket so it makes things a lot easier. What makes the WD90C30 so good? It is fast and has good compatibility but most …

Re: Copam U-series 486

Posted on 2021-06-30, 16:46

I took a look what the RAMDAC in the DECpc is. It happens to be Sierra semiconductor RAMDAC but too good one, SC15025. It doesn't even support 6-bit mode so I can forget that. I did more testing about possible speed sensitivity of the Bt RAMDAC. Setting CPU to 16 MHz did not help but disabling …

Re: Copam U-series 486

Posted on 2021-06-30, 11:23

This is from Bt datasheet: "Occasional accesses to the color palette RAM can be made without noticeable disturbance on the display screen; however, operations requiring frequent access to the color palette (such as block fills of the color palette) should take place during the blanking interval." …

Re: Copam U-series 486

Posted on 2021-06-30, 05:08

I had to put the UMC RAMDAC back last night for testing. I noticed some graphics errors (color dots) with the Bt RAMDAC and I was pretty sure the UMC did not have them. And it didn't. These dots that the Bt displays are usually visible while loading etc and not during gameplay. So these are related …

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