English Amiga Board - View Single Post - UHRES? Mistery/curiosity

chb · 30 September 2019, 19:32

Maybe not strictly UHRES related, but as it concerns ECS and may (or not) give some clues about UHRES, I'll post it here:
I noticed something interesting when having a look with the UAE debugger at the A2024 JumpStart disk, which is a special WB disk containing kick 1.4-beta code (exec v35.6, graphics 35.15, intution 35.45) to support the A2024 monitor and it's higher resolution. It is from 1988.

Now what's interesting about it? It reads VPOSR for the Agnus revision, but also DENISEID. The latter register was only introduced with the ECS Denise. It checks for value 0xfc (ECS Denise 8373) and 0xfe (according to this document, also from 1988 btw., a prototype Denise numbered 8369). Both values result in the same operation (bit set in memory, probably some structure like GfxBase->ChipRevBits0), so one could speculate that they were largely functional identical.

I only had a brief look, and my 68000 assembler skills are really rusty, so atm I could not see what it's used for. At least I do not see any writes to the UHRES related registers. But there may still be a chance that something is burried in some code that they failed to remove and that is never executed. It may be, of course, just contain some support for the known ECS enhancements or nothing at all.

It's rather stunning that Commodore had the ECS Agnus and Denise already in 1988 and maybe even a bit earlier, judging from the 8369 prototype mentioned in the above doc, and did not release it officially until mid-1990 with the A3000...

30 September 2019, 19:32	#48
chb Registered User Join Date: Dec 2014 Location: germany Posts: 400	Maybe not strictly UHRES related, but as it concerns ECS and may (or not) give some clues about UHRES, I'll post it here: I noticed something interesting when having a look with the UAE debugger at the A2024 JumpStart disk, which is a special WB disk containing kick 1.4-beta code (exec v35.6, graphics 35.15, intution 35.45) to support the A2024 monitor and it's higher resolution. It is from 1988. Now what's interesting about it? It reads VPOSR for the Agnus revision, but also DENISEID. The latter register was only introduced with the ECS Denise. It checks for value 0xfc (ECS Denise 8373) and 0xfe (according to this document, also from 1988 btw., a prototype Denise numbered 8369). Both values result in the same operation (bit set in memory, probably some structure like GfxBase->ChipRevBits0), so one could speculate that they were largely functional identical. I only had a brief look, and my 68000 assembler skills are really rusty, so atm I could not see what it's used for. At least I do not see any writes to the UHRES related registers. But there may still be a chance that something is burried in some code that they failed to remove and that is never executed. It may be, of course, just contain some support for the known ECS enhancements or nothing at all. It's rather stunning that Commodore had the ECS Agnus and Denise already in 1988 and maybe even a bit earlier, judging from the 8369 prototype mentioned in the above doc, and did not release it officially until mid-1990 with the A3000...