reifsnyderb Posted December 21, 2022 Share Posted December 21, 2022 This thread got me thinking some about what it would take to make my 600XL run a little faster. https://forums.atariage.com/topic/345302-revision-c-basic-error-that-does-not-show-in-rev-a-or-altirra-basic/ My 600XL had OS V. 4 and BASIC R. C. installed and I normally run it with either a 1090 board/320k RAM card or one of my PBI RAM cards installed directly. However, it's possible to install Fast Chip in an Atari 800 to get better floating point performance. It's also a known fact that Altirra BASIC runs much faster than Atari BASIC. So, a good combination would be to change out the floating point package on the OS V. 4 with the Fast Chip ROM and to swap out the Atari BASIC with Altirra BASIC. The XL/XE OS also has a checksum to deal with so I tracked down a program to update the checksum. I know this will cause speed compatibility problems with some software but I'll have to see how well it works out overall. Attached is the modified Atari OS4 ROM with Fast Chip installed: AtariOSR4wFC.rom Program, with instructions, to update the checksum bytes: Hias PatchROM-1.33.zip Floating Point Operations Test: System information after changes made: Atari 600XL w/1090 board: 1 1 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted December 21, 2022 Share Posted December 21, 2022 (edited) what would be gained if perhaps more things got done during DMA and VBI possibly at the same times and separately also what happens during retrace ... might get us a little and every little bit counts that's OS level changes for sure but hey why not PBI and other keyholes are time honored and well complete personality and support cards from Newell etc right on down to incognito u1m etc show some possibility. Edited December 21, 2022 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted December 21, 2022 Author Share Posted December 21, 2022 32 minutes ago, _The Doctor__ said: what would be gained if perhaps more things got done during DMA and VBI possibly at the same times and separately also what happens during retrace ... might get us a little and every little bit counts that's OS level changes for sure but hey why not PBI and other keyholes are time honored and well complete personality and support cards from Newell etc right on down to incognito u1m etc show some possibility. Do you know of any OS patches, that maintain compatibility, and take advantage of this? Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted December 21, 2022 Share Posted December 21, 2022 don't think anyone has attempted for these purposes but the the DMA (screen off) speed up is use a bit as well as shortened display lists. No one has ever gone to the bare metal OS interaction time as yet, but it's been theorized at parties. Quote Link to comment Share on other sites More sharing options...
Rybags Posted December 22, 2022 Share Posted December 22, 2022 Screen changes really should be up to the programmer. You'd likely find the fastest combination is a PAL machine. Even though the master clock is a bit slower, it has less VBlank CPU overhead as well as less overall screen and refresh DMA which gives it a better net speed. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted December 22, 2022 Share Posted December 22, 2022 (edited) Why not let NTSC compete as well? It's pretty darn close already because more frames in the same time period. This can be fixed possibly, lets not keep saying do everything in PAL, I like the silky smooth NTSC, PAL is jerky and slow in screen updates PAL 60 hints NTSC can be helped. We already know OS has line error mistake. Maybe fixes/hacks will help both do more? WIN WIN Edited December 22, 2022 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
+CharlieChaplin Posted December 22, 2022 Share Posted December 22, 2022 Now that there is a patched ROM of XL-Os Rev. 4 with fast FP routines, I would be happy, if someone would also post patched ROM versions (that could be burned onto a 16k Eprom) with fast FP routines for a) OS-A (PAL, NTSC), b) OS-B (PAL, NTSC), c) XL-OS Rev. 2 and d) XL-OS Rev. 3. Since I only have PAL Atari 800XL computers, I would need PAL versions and 16k size (so even OS-A and OS-B must be 16k ROMs to use them in the XL computer)... Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted December 22, 2022 Author Share Posted December 22, 2022 Here's the Fast Chip ROM. It's the same as used on an Atari 800. To make a patched ROM you take a copy of the OS ROM and overwrite it with this ROM starting at the offset of $1800. Then you have to run the previously posted patchrom command. i.e. "patchrom -C sourcefile destfile" With Windows 10, you need to run the command prompt as admin. FastChip.rom I've got all these files from this forum....somewhere. 1 Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted December 22, 2022 Author Share Posted December 22, 2022 3 hours ago, CharlieChaplin said: Now that there is a patched ROM of XL-Os Rev. 4 with fast FP routines, I would be happy, if someone would also post patched ROM versions (that could be burned onto a 16k Eprom) with fast FP routines for a) OS-A (PAL, NTSC), b) OS-B (PAL, NTSC), c) XL-OS Rev. 2 and d) XL-OS Rev. 3. Since I only have PAL Atari 800XL computers, I would need PAL versions and 16k size (so even OS-A and OS-B must be 16k ROMs to use them in the XL computer)... I found some of what you are looking for here: https://atariwiki.org/wiki/Wiki.jsp?page=Articles#section-Articles-OperatingSystemsOS 1 Quote Link to comment Share on other sites More sharing options...
Steve Mynott Posted December 23, 2022 Share Posted December 23, 2022 Probably a silly question but what's the name of the FP benchmark? Quote Link to comment Share on other sites More sharing options...
+Stephen Posted December 23, 2022 Share Posted December 23, 2022 5 hours ago, Steve Mynott said: Probably a silly question but what's the name of the FP benchmark? I believe that is from SysInfo. SysInfo v2.24 (2014-08-01)(Kokoszkiewicz, Konrad M.)(PL)(en).atr 1 Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted December 23, 2022 Author Share Posted December 23, 2022 47 minutes ago, Stephen said: I believe that is from SysInfo. SysInfo v2.24 (2014-08-01)(Kokoszkiewicz, Konrad M.)(PL)(en).atr 90.02 kB · 0 downloads It is. 1 Quote Link to comment Share on other sites More sharing options...
luckybuck Posted January 14, 2023 Share Posted January 14, 2023 (edited) JAC! has finished this a few hours ago: Please take into account to use the Fast Math Version F+ The obj file is attached, too. https://atariwiki.org/wiki/Wiki.jsp?page=FAST FLOATING POINT source code for the ATARI Atari OS Rev 2 (1983) (Atari) (800XL-65XE-130XE)-FASTFP.rom FASTFP.OBJ Edited January 14, 2023 by luckybuck 5 Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted January 14, 2023 Author Share Posted January 14, 2023 8 hours ago, luckybuck said: JAC! has finished this a few hours ago: Please take into account to use the Fast Math Version F+ The obj file is attached, too. https://atariwiki.org/wiki/Wiki.jsp?page=FAST FLOATING POINT source code for the ATARI Atari OS Rev 2 (1983) (Atari) (800XL-65XE-130XE)-FASTFP.rom 16 kB · 2 downloads FASTFP.OBJ 2.01 kB · 1 download Is this F+ Version part of the attached OS Rev 2 ROM file? Quote Link to comment Share on other sites More sharing options...
luckybuck Posted January 14, 2023 Share Posted January 14, 2023 Yes, it is. Therefore final. 🙂 40 years later... 1 Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted January 14, 2023 Author Share Posted January 14, 2023 Here's Atari OS R4 with Fast Math Version F+. AtariOSR4wFMvFplus.rom Oddly enough, ? SQR(2^2) still gives 1.99999999 in Altirra BASIC 1.58. However, it does give 2 with Atari BASIC R. C. I ran the floating point math speed test in SysInfo v2.24 and discovered no speed increase over the Fast Chip ROM I used earlier. I've installed this ROM in my 600XL. 🙂 Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted January 15, 2023 Author Share Posted January 15, 2023 Here's OS R. 4a with the Fast Floating Point F+ and patched for the proper banks on an Atari 130XE. (I decided to call it R. 4a.) Atari_OS_R_4A_w_FM_vF_plus.rom To patch the bank table, I used a hex editor to swap out the existing bank table and install the bank table as per the comment in the source code. The comment, in the source code, appears to be correct due to the bits set as opposed to the bits set as per the original table. I wasn't able to test it on a machine with bad memory, though. The checksum was changed and the OS runs on Altirra. I'll install it in my real machines, of course. Starting on line 5686, here's the source code and comment I used: ** TXEB - Table of XE Banks * * NOTES * Problem: should be $0,$4,$8,$C to correctly test all banks TXEB DB $0,$2,$4,$6 3 1 Quote Link to comment Share on other sites More sharing options...
markmiller Posted November 4, 2023 Share Posted November 4, 2023 On 1/14/2023 at 4:48 PM, reifsnyderb said: Oddly enough, ? SQR(2^2) still gives 1.99999999 in Altirra BASIC 1.58. However, it does give 2 with Atari BASIC R. C. I listened to an interview with someone from Atari, years ago, and he revealed that they knew their FP routines were somewhat inaccurate, and I think the guy said they would find it embarrassing if people tried SQR(4) and got back an imprecise answer. So, to avoid that, they hardcoded this particular case. SQR() tests if you're giving it 4, and if so, it returns 2, with no computation! Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted November 5, 2023 Author Share Posted November 5, 2023 1 hour ago, markmiller said: I listened to an interview with someone from Atari, years ago, and he revealed that they knew their FP routines were somewhat inaccurate, and I think the guy said they would find it embarrassing if people tried SQR(4) and got back an imprecise answer. So, to avoid that, they hardcoded this particular case. SQR() tests if you're giving it 4, and if so, it returns 2, with no computation! Very interesting! What I also find interesting is that Atari never changed their FP routines even though faster FP routines were available. Quote Link to comment Share on other sites More sharing options...
+mytek Posted November 5, 2023 Share Posted November 5, 2023 1 minute ago, reifsnyderb said: What I also find interesting is that Atari never changed their FP routines even though faster FP routines were available. It would have affected many pre-existing applications, especially games, especially ones that used timing loops. 2 Quote Link to comment Share on other sites More sharing options...
luckybuck Posted November 5, 2023 Share Posted November 5, 2023 https://atariwiki.org/wiki/Wiki.jsp?page=FAST FLOATING POINT source code for the ATARI 3 Quote Link to comment Share on other sites More sharing options...
tebe Posted November 5, 2023 Share Posted November 5, 2023 Mad Assembler version https://github.com/tebe6502/Mad-Assembler/tree/master/examples/math/fastchip 2 Quote Link to comment Share on other sites More sharing options...
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