MDEC Output: Difference between revisions
| Revision as of 05:11, 23 October 2026 RemmyLee (Hardware tests: 72 more test pages, listed on the main page by area; RUN.toml no longer published) | Revision as of 05:18, 23 October 2026 RemmyLee (Hardware tests: nine DMA, MDEC and BIOS test pages with part names for titles; join one-sentence paragraphs per voice.md) | ||
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| ### Table Loads | ### Table Loads | ||
| − | MDEC(2) with bit 0 clear takes 16 words (the luminance table only) and with bit 0 set 32 words. MDEC(3) takes 32 words whatever its bits 0 to 15 hold. The low 16 bits of the status count down from the number of words minus 1 to 0 and then read FFFFh.[^h-tbl] | + | MDEC(2) with bit 0 clear takes 16 words (the luminance table only) and with bit 0 set 32 words. MDEC(3) takes 32 words whatever its bits 0 to 15 hold. The low 16 bits of the status count down from the number of words minus 1 to 0 and then read FFFFh.[^h-tbl] A table load cut short by a word does not end the load: the next word written, even a command, is taken as table data.[^h-tbl] |
| − | A table load cut short by a word does not end the load: the next word written, even a command, is taken as table data.[^h-tbl] | ||
| − | |||
| ### Decoding | ### Decoding | ||
| − | The step stream decoded by CPU gave 512 words at 15 bit and 768 at 24 bit. Every repeat of the test gave the same CRC. Written one word at a time with reads between, the stream gave the same 512 words and CRC.[^h-s15][^h-ear] | + | The step stream decoded by CPU gave 512 words at 15 bit and 768 at 24 bit. Every repeat of the test gave the same CRC. Written one word at a time with reads between, the stream gave the same 512 words and CRC.[^h-s15][^h-ear] Command bit 25 (bit 15 output) left 4-bit and 8-bit output unchanged, and the status showed it in bit 23.[^h-blk] |
| − | Command bit 25 (bit 15 output) left 4-bit and 8-bit output unchanged, and the status showed it in bit 23.[^h-blk] | ||
| − | |||
| A decode command whose word count cuts the stream gave fewer words than the stream holds. A count of 33 or 233 left the MDEC waiting for more input.[^h-odd] | A decode command whose word count cuts the stream gave fewer words than the stream holds. A count of 33 or 233 left the MDEC waiting for more input.[^h-odd] | ||