Hello Dave, here is the result of the previous post:I'm not sure what's going on here. I've compared the CPLDs from YARRBv1 and YARRBv2 and can't see any significant differences.@Roland, are you following this thread?
For reference, here's the source of TEST:The purpose of this is to identify the type of RomRam board fitted. The return values are:Code:
10 DIMLL10 20 FOR I=0 TO 1 30 P=#2800 40[ 50 LDA @#00 60 STA #80 70 LDA #BFFE 80 EOR @#80 90 STA #BFFE 100 CMP #BFFE 110 PHP 120 EOR @#80 130 STA #BFFE 140 PLP 150 BEQ LL1 155 AND @#F1 160 CMP @#B1 170 BEQ LL0 190 LDA @#01 200 STA #80 210:LL0 220 RTS 230:LL1 240 AND @#10 250 BNE LL4 260 LDA #BFFE 270 LDX @#5A 280 STX #4000 290 EOR @#01 300 STA #BFFE 310 LDX @#A5 320 STX #4000 330 EOR @#01 340 STA #BFFE 350 LDX #4000 360 CPX @#5A 370 BEQ LL2 380 CPX @#A5 390 BEQ LL3 400 LDA @#FF 410 STA #80 420 RTS 430:LL2 440 LDA @#02 450 STA #80 460 RTS 470:LL3 480 LDA @#03 490 STA #80 500 RTS 510:LL4 520 LDA #BFFE 530 TAX 540 AND @#FB 550 STA #BFFE 560 LDA #A00 570 EOR @#FF 580 STA #A00 590 CMP #A00 600 PHP 610 EOR @#FF 620 STA #A00 630 STX #BFFE 640 PLP 650 BEQ LL2 660 BNE LL3 670] 680 NEXT 690 LINK #2800 700 P.&?#80' 710 END
- 00 = No RAM ROM board detected
- 01 = Unsupported RAM ROM board (e.g. Phill's which doesn't support soft-loading of ROMs)
- 02 = Atom2015
- 03 = YARRB
- FF = Something unexpected occurred
Although it does modify BFFE, it's careful to always restore the original value. What I suspect is happening is a read of BFFE is getiing corrupted, and the value written back then has bit 2 cleared when it should be set, which switches the ROM set to one that doesn't include AtoMMC.
Erik, do run the tests suggested in the previous post, as they may help narrow down the issue.
Dave
Statistics: Posted by dreamerxb — Wed Mar 20, 2024 4:11 pm