| Author |
Message |
Forum: Forth Topic: Best register usage for 65C816 Forth? |
| BruceRMcF |
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Posted: Sun Jul 03, 2022 1:53 pm
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Replies: 24
Views: 15098
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| ... my comment was left entirely obscure. I've updated the comment to try to make it clearer that I was using BitWise's intriguing suggestion as a springboard in reacting to a point in Dr Jefyll's post. It occurs to me just now that one could also flip BitWise's use of the direct page register ... |
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Forum: Hardware Topic: Z50 based retro 6502 computer |
| Chromatix |
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Posted: Sun Apr 19, 2020 11:58 am
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Replies: 9
Views: 1062
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| If you first test ZP, and prove that it does work, then you can use it as a springboard to test the rest. |
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Forum: Programming Topic: Callback Tables |
| Runic_Rain |
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Posted: Thu Jul 25, 2019 11:36 pm
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Replies: 15
Views: 1849
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| ... from everyone helped as well! @Dr.Jefyll's stack manipulation seems to fit the bill for me. Given I am *heavily* byte constrained. The springboard you were all talking about is definitely the most elegant in my opinion and if I can make room I might shift to that. I guess I was missing ... |
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Forum: Programming Topic: Callback Tables |
| barrym95838 |
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Posted: Tue Jul 23, 2019 3:24 pm
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Replies: 15
Views: 1849
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| ... nearby in the same bank with the array? If I'm not mistaken, you can then simply JSL al to your JMP (jumptable,x) from anywhere, and the double springboard does the rest for you (at the expense of an extra byte for each array element, a 3-byte JMP and a handful of machine cycles). |
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Forum: Programming Topic: Callback Tables |
| Chromatix |
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Posted: Tue Jul 23, 2019 2:23 pm
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Replies: 15
Views: 1849
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| The springboard doesn't need to be anywhere near the jump table itself. In particular it exists in Program space while the table is accessed through Absolute data space, so may be in different banks of memory. |
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Forum: Programming Topic: Callback Tables |
| Runic_Rain |
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Posted: Tue Jul 23, 2019 6:39 am
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Replies: 15
Views: 1849
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| ... long, not the most elegant, and makes the question read more like: "Do it for me!" :P (All this assuming I'm understanding the intended springboard correctly of course.) |
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Forum: Programming Topic: Callback Tables |
| barrym95838 |
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Posted: Tue Jul 23, 2019 3:52 am
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Replies: 15
Views: 1849
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| Yes! The "springboard" technique can potentially be very useful and economical in these types of situations. |
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Forum: General Discussions Topic: Vectoring with the SYM-1 |
| barrym95838 |
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Posted: Fri Mar 01, 2019 4:24 pm
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Replies: 4
Views: 490
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| ... missing is how to return properly from a JMP (COUT) instruction, since the base 6502 doesn't have a JSR (COUT) instruction. The answer is to use a springboard JMP, either in RAM or ROM. When a program wishes to send a char, it simply does a JSR COUT, which saves the proper return address on the ... |
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Forum: Newbies Topic: Dan's 6502 build, aka, The WOPR Jr. |
| barrym95838 |
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Posted: Sun Feb 11, 2018 9:12 pm
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Replies: 320
Views: 41036
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| The "springboard" method is easier than manually pushing any hard-coded addresses. All you need to do is find a little out-of-the-way spot to stick springboard: JMP (SELECTED_CMD) then GET some_stuff_done JSR springboard ... |
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Forum: Newbies Topic: Dan's 6502 build, aka, The WOPR Jr. |
| Dr Jefyll |
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Posted: Sun Feb 11, 2018 7:00 pm
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Replies: 320
Views: 41036
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| ... what routine I'm going to run until the last minute. Alright. (Ideally what you want is a JSR using indirect mode. And that can be faked with a springboard as Mike said -- by manually pushing the return address then doing an indirect JMP, but never mind that now.) JSR process_cmdln ;index arguments, ... |
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Forum: Newbies Topic: Dan's 6502 build, aka, The WOPR Jr. |
| barrym95838 |
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Posted: Sun Feb 11, 2018 6:08 pm
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Replies: 320
Views: 41036
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| ... a sudden swerve into the weeds like the one you describe. There is no JSR (abs) on the 65c02, but it can be easily simulated with a little "springboard", if you decide to pursue that path. Mike B. |
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Forum: Newbies Topic: Challenge Understanding Clock Cycle Diagram |
| GARTHWILSON |
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Posted: Wed May 11, 2016 9:15 am
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Replies: 22
Views: 3018
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| ... promoting our interest, for the sake of our interest. And with each newbie we dialog with, we get better at helping the next one. Every topic is a springboard for exchanging and developing more ideas too. I know I myself learn from helping others. I've tried learning C# as a first language, but ... |
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Forum: Hardware Topic: Chuck's concept |
| Nightmaretony |
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Posted: Tue Mar 09, 2010 6:25 pm
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Replies: 6
Views: 3251
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| Use as a springboard. My own pinball project started life as a similar setup to his SBC1, but it is veering off into wild directions so it will use a CPLD and sound system as well as drivers. Springboard and acknowledgement... |
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