Author
| Snatcher Sound Cartridge - programming HELP!
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pitpan
msx master
Posts: 1368 |  Posted: January 20 2005, 10:54 |
Hi everyone!
I received yesterday this tiny wonder, SCC+ with 64 KB of RAM. I have been able to access the SCC+ and use it properly, but I do not know how to actually write to the RAM. I can select the different pages, just writting to convenient addresses, but it appears to be ROM, not RAM.
HELP!
What I am supposed to do to write to the RAM pages and then "lock" them again so that they will appear to be ROM? I guess BiFi has got some extra knowledge on this topic.
Just in case, I will explain here how to access the SCC+ from BASIC. It was a lot of fun!
I did it on a standard MSX1 machine with 64 KB of RAM on the third slot, and SCC+ was plugged into the first slot.
OUT &HA8,&b11010000
This lets only RAM on the third page, the Sound Cartridge on the second page, and the BIOS and BASIC interpreter in the lowest two pages.
Then, to enable SCC
POKE &H9000,&h3F
And here you go! Now you can POKE all the SCC/SCC+ addresses to "test" how it sounds!
POKE &h988a,15
Maximum amplitude for channel 1
POKE &h988f,1
Enable channel 1 (I am typing it without references, maybe the address is wrong)
You can of course, change the wave information, the frequency, etc.
Only direct-mode MSX basic commands are allowed. If you try to store a BASIC program with line numbers, it will probably hang.
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BiFi
msx guru
Posts: 3142 | Posted: January 20 2005, 11:37 |
Access register address &HBFFE:
bit 7 = unused
bit 6 = unused
bit 5 = select SCC/SCC-I mode (1 = SCC-I, or SCC+)
bit 4 = all range RAM mode (1 = RAM)
bit 3 = area &HA000 - &HBFFF RAM mode (inhibit as the access register is in here)
bit 2 = area &H8000 - &H9FFF RAM mode (1 = RAM)
bit 1 = area &H6000 - &H7FFF RAM mode (1 = RAM)
bit 0 = area &H4000 - &H5FFF RAM mode (1 = RAM)
Konami usually writes &H3F to enable writing to RAM and &H20 to disable it again.
I need to correct something here as well. At startup the access of the sound chip are set in SCC mode, which means the addresses pitpan provided in his post are valid. To get the SCC-I, or SCC+) mode, you need to set bit 5 in &HBFFE.
Then you're required to do:
POKE &HB000,&H80
In the area &HB800-&HB8AF the SCC-I is accessible:
&HB800 - &HB81F = Channel A wave area (SCC = &H9800 - &H981F)
&HB820 - &HB83F = Channel B wave area (SCC = &H9820 - &H983F)
&HB840 - &HB85F = Channel C wave area (SCC = &H9840 - &H985F)
&HB860 - &HB87F = Channel D wave area (SCC = &H9860 - &H987F)
&HB880 - &HB89F = Channel E wave area (SCC = Channel D wave mirror)
&HB8A0 - &HB8A9 = Frequency registers (SCC = &H9880 - &H9889)
&HB8AA - &HB8AE = Volume registers (SCC = &H988A - &H988E)
&HB8AF = Channel switch (000EDCBA, 1 = audible) (SCC = &H988F)
This info was previously available on msxnet.org, but has been moved to Wikipedia. |
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Sonic_aka_T
msx guru
Posts: 2262 | Posted: January 20 2005, 11:56 |
Quote:
| Hi everyone!
I received yesterday this tiny wonder, SCC+ with 64 KB of RAM.
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Which one did you get? (say SNATCHER!) |
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BiFi
msx guru
Posts: 3142 | Posted: January 20 2005, 12:08 |
One more thing you might need to know...
The Snatcher Sound Cartridge has its 64 KB in banks 0-7, while the SD-Snatcher Sound Cartridge has it in banks 8-15.
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pitpan
msx master
Posts: 1368 | Posted: January 20 2005, 15:05 |
Sonic, I said "SNATCHER" on the topic name. But once expanded, both SD-Snatcher and Snatcher sound cartridges are just the same thing.
BiFi: thank you very much for your detailed information! I will make some tests this evening!
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Sonic_aka_T
msx guru
Posts: 2262 | Posted: January 20 2005, 15:15 |
Quote:
| Sonic, I said "SNATCHER" on the topic name.
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**DUH** (slaps self in the face) |
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Sonic_aka_T
msx guru
Posts: 2262 | Posted: January 20 2005, 15:16 |
Quote:
| But once expanded, both SD-Snatcher and Snatcher sound cartridges are just the same thing.
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Well, there's a certain coolness to SNATCHER that SD-Snatcher misses IMHO. I'd *much* rather own an original SNATCHER than an SD-Snatcher... |
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snout
msx legend
Posts: 4991 | Posted: January 20 2005, 15:18 |
now lets wait for the first "I own both of them" -post 
(ps.. I do own both of them ^_^) |
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[D-Tail]
msx guru
Posts: 2994 | Posted: January 20 2005, 19:29 |
I own none of them. Does that count as well? >  ) |
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BiFi
msx guru
Posts: 3142 | Posted: January 20 2005, 20:44 |
I own both of them as well...
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dhau
msx master
Posts: 1047 | Posted: January 21 2005, 01:21 |
I own a mighty one  I upgraded my Snatcher cart to 128Kb and it's just great, thanks to Master BiFi |
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[D-Tail]
msx guru
Posts: 2994 | Posted: January 21 2005, 06:13 |
Yeah, I wonder... What extra does it have, when you've got your (SD-)Snatcher memory expanded? Will you be able to use it as RAM or so?
Curious!
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BiFi
msx guru
Posts: 3142 | Posted: January 21 2005, 07:44 |
You will be able to upload MegaROM titles to it. Otherwise it'd only work well for titles up to 32K (or 64K when you're using a Snatcher Sound Cartridge). Look for a tool called ROMLOAD in the downloads database. |
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pitpan
msx master
Posts: 1368 | Posted: January 21 2005, 11:24 |
Hi! After carefully reading BiFi's explanations I have coded a tiny program that converts ROMs (megaROMs not yet!) to WAV files, so that the games can be uploaded to the SOUND CARTRIDGE using the cassette interface at high speeds (8,250 bauds instead of 1,200/2,400).
I will make some tests using 48/64 KB ROMs (they do include mapper) and then I will release it. Indeed, it is a "cassette" version of ROMLOAD. My goal is to make it as compatible as possible, to be able to use an MSX1 with 16 KB and no disk drive as a complete ROM/megaROM testing workbench.
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pitpan
msx master
Posts: 1368 | Posted: January 21 2005, 11:36 |
And by the way, has anyone got some spare RAM chips for the upgrade? I am really interested in getting two of them. And I will pay, of course.
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