INTERTON VC 4000 CODING GUIDE ----------------------------- This document was written on 7/2/07, and last updated on 27/12/17, by James Jacobs of Amigan Software. Information herein is believed to be generally accurate, though most is tentative and incomplete. If you have anything to contribute, please email amigansoftware@gmail.com. Thanks to Manfred Schneider and Peter Trauner for their contributions. Disassembly, comprehension and patching can be done in the same way as described in the Emerson Arcadia 2001 Coding Guide. ANNOTATE supports the Interton VC 4000; remember to use the appropriate INTERTON_? argument. HOWDIF is also of course usable for this machine (though the Arcadia character set output is not relevant for it). Annotated disassemblies of every available Interton ROM are now available, so therefore you should not normally need to use DASMX or ANNOTATE. Some available disassemblies were made using older versions of ANNOTATE; the memory maps included in such disassemblies are obsolete and inaccurate. You should always use the latest version of ANNOTATE. Memory Maps ----------- "Motherboard RAM" is RAM that is built into the console unit. "Cartridge RAM" is additional RAM that is provided onboard certain game cartridges. "PVI RAM" is motherboard RAM in the $1Fxx area. There are four different cartridge configurations known: A: 2K ROM/EPROM + 0K RAM (most games): $0000..$07FF: game ROM/EPROM (2K) $0800..$15FF: unused $1600..$17FF: mirror of $1E00..$1FFF $1800..$1DFF: unused $1E00..$1EFF: "I/O area" $1F00..$1FFF: PVI area $2000..$3FFF: mirror of $0000..$1FFF $4000..$5FFF: mirror of $0000..$1FFF $6000..$7FFF: mirror of $0000..$1FFF B: 4K ROM/EPROM + 0K RAM (some games): $0000..$0FFF: game ROM/EPROM (4K) $1000..$15FF: unused $1600..$17FF: mirror of $1E00..$1FFF $1800..$1DFF: unused $1E00..$1EFF: "I/O area" $1F00..$1FFF: PVI area $2000..$3FFF: mirror of $0000..$1FFF $4000..$5FFF: mirror of $0000..$1FFF $6000..$7FFF: mirror of $0000..$1FFF C: 4K ROM + 1K RAM (Backgammon, Chess and Draughts only): $0000..$0FFF: game ROM (4K) $1000..$13FF: 1K of cartridge RAM $1400..$15FF: mirror of $1000..$11FF $1600..$17FF: mirror of $1E00..$1FFF $1800..$1DFF: mirror of $1000..$15FF $1E00..$1EFF: "I/O area" $1F00..$1FFF: PVI area $2000..$3FFF: mirror of $0000..$1FFF $4000..$5FFF: mirror of $0000..$1FFF $6000..$7FFF: mirror of $0000..$1FFF D: 6K ROM + 1K RAM (Chess 2 only): $0000..$15FF: game ROM (6K ROM chip, but only 5½K is usable) $1600..$17FF: mirror of $1E00..$1FFF (obscures 512 bytes of ROM) $1800..$1BFF: 1K of cartridge RAM $1C00..$1DFF: mirror of $1800..$19FF $1E00..$1EFF: "I/O area" $1F00..$1FFF: PVI area $2000..$3FFF: mirror of $0000..$1FFF $4000..$5FFF: mirror of $0000..$1FFF $6000..$7FFF: mirror of $0000..$1FFF ;Hardware Equates/Memory Map (Interton VC 4000)--------------------------- ; $0000..$07FF: (R/-) A-D: ROM ; $0800..$08BF: (-/-) A: unused ; (R/-) B-D: ROM ; $08C0..$0FFF: (-/-) A: unused ; (R/-) B-D: ROM ; $1000..$13FF: (-/-) A-B: unused ; (R/W) C: 1K of cartridge RAM ; (R/-) D: ROM ; $1400..$15FF: (-/-) A-B: unused ; (R/W) C: mirror of $1000..$11FF ; (R/-) D: ROM ; $1600..$17FF: (*/*) A-D: mirror of $1E00..$1FFF ; $1800..$1BFF: (-/-) A-B: unused ; (R/W) C: mirror of $1000..$13FF ; (R/W) D: 1K of cartridge RAM ; $1C00..$1DFF: (-/-) A-B: unused ; (R/W) C: mirror of $1400..$15FF ; (R/W) D: mirror of $1800..$19FF ; $1E00..$1E7F: (-/-) unused NOISE equ $1E80 ;(?/W) noise register ; bits 7..6: volume: ; %00 = high (full?) ; %01 = medium high (3/4?) ; %10 = medium low (2/4?) ; %11 = low (1/4?) ; bit 5: bright backgrounds on/off ; bit 4: start explosion (>= 20 msec) ; bit 3: PVI tone on/off ; bit 2: noise on/off ; bits 1..0: unmapped ; $1E81..$1E87: (-/-) unmapped P1LEFTKEYS equ $1E88 ;(R/-) ; bit 7: p1 (left) '1' button ; bit 6: p1 (left) '4' button ; bit 5: p1 (left) '7' button ; bit 4: p1 (left) 'C' button (Clear) ; bits 3..0: unused P1MIDDLEKEYS equ $1E89 ;(R/-) ; bit 7: p1 (left) '2' button ; bit 6: p1 (left) '5' button ; bit 5: p1 (left) '8' button ; bit 4: p1 (left) '0' button ; bits 3..0: unused P1RIGHTKEYS equ $1E8A ;(R/-) ; bit 7: p1 (left) '3' button ; bit 6: p1 (left) '6' button ; bit 5: p1 (left) '9' button ; bit 4: p1 (left) 'E' button (Enter) ; bits 3..0: unused CONSOLE equ $1E8B ;(R/-) ; bit 7: 'SELECT' button ; bit 6: 'START' button ; bits 5..0: unused P2LEFTKEYS equ $1E8C ;(R/-) ; bit 7: p2 (right) '1' button ; bit 6: p2 (right) '4' button ; bit 5: p2 (right) '7' button ; bit 4: p2 (right) 'C' button (Clear) ; bits 3..0: unused P2MIDDLEKEYS equ $1E8D ;(R/-) ; bit 7: p2 (right) '2' button ; bit 6: p2 (right) '5' button ; bit 5: p2 (right) '8' button ; bit 4: p2 (right) '0' button ; bits 3..0: unused P2RIGHTKEYS equ $1E8E ;(R/-) ; bit 7: p2 (right) '3' button ; bit 6: p2 (right) '6' button ; bit 5: p2 (right) '9' button ; bit 4: p2 (right) 'E' button (Enter) ; bits 3..0: unused ; $1E8F..$1E97 (-/-) unmapped ; $1E98..$1E9B (R/-) mirror of $1E88..$1E8B ; $1E9C..$1EA7 (-/-) unmapped ; $1EA8..$1EAE (R/-) mirror of $1E88..$1E8E ; $1EAF..$1EB7 (-/-) unmapped ; $1EB8..$1EBB (R/-) mirror of $1E88..$1E8B ; $1EBC..$1EC7 (-/-) unmapped ; $1EC8..$1ECE (R/-) mirror of $1E88..$1E8E ; $1ECF..$1ED7 (-/-) unmapped ; $1ED8..$1EDB (R/-) mirror of $1E88..$1E8B ; $1EDC..$1EE7 (-/-) unmapped ; $1EE8..$1EEE (R/-) mirror of $1E88..$1E8E ; $1EEF..$1EF7 (-/-) unmapped ; $1EF8..$1EFB (R/-) mirror of $1E88..$18EB ; $1EFC..$1EFF (-/-) unmapped ; $1F00..$1F09: (R/W) imagery for sprite #0 (8*10) SPRITE0AX equ $1F0A ;(R/W) SPRITE0BX equ $1F0B ;(R/W) SPRITE0AY equ $1F0C ;(R/W) SPRITE0BY equ $1F0D ;(R/W) ; $1F0E..$1F0F: (R/W) PVI RAM ; $1F10..$1F19: (R/W) imagery for sprite #1 (8*10) SPRITE1AX equ $1F1A ;(R/W) SPRITE1BX equ $1F1B ;(R/W) SPRITE1AY equ $1F1C ;(R/W) SPRITE1BY equ $1F1D ;(R/W) ; $1F1E..$1F1F: (R/W) PVI RAM ; $1F20..$1F29: (R/W) imagery for sprite #2 (8*10) SPRITE2AX equ $1F2A ;(R/W) SPRITE2BX equ $1F2B ;(R/W) SPRITE2AY equ $1F2C ;(R/W) SPRITE2BY equ $1F2D ;(R/W) ; $1F2E..$1F3F: (-/-) unmapped ; $1F40..$1F49: (R/W) imagery for sprite #3 (8*10) SPRITE3AX equ $1F4A ;(R/W) SPRITE3BX equ $1F4B ;(R/W) SPRITE3AY equ $1F4C ;(R/W) SPRITE3BY equ $1F4D ;(R/W) ; $1F4E..$1F6D: (R/W) PVI RAM ; $1F6E..$1F7F: (-/-) unmapped ; $1F80..$1FA7 ;(R/W) vertical grid HORIZ1 equ $1FA8 ;(R/W) horizontal grid #1 HORIZ2 equ $1FA9 ;(R/W) horizontal grid #2 HORIZ3 equ $1FAA ;(R/W) horizontal grid #3 HORIZ4 equ $1FAB ;(R/W) horizontal grid #4 HORIZ5 equ $1FAC ;(R/W) horizontal grid #5 ; $1FAD: (R/W) PVI RAM ; $1FAE..$1FBF: (-/-) unmapped SIZES equ $1FC0 ;(-/W) ; bits 7..6: sprite #3 size (%00..%11) ; bits 5..4: sprite #2 size (%00..%11) ; bits 3..2: sprite #1 size (%00..%11) ; bits 1..0: sprite #0 size (%00..%11) SPR01COLOURS equ $1FC1 ;(-/W) ; bits 7..6: unused ; bits 5..3: colour of sprite #0 ; (inverted RGB mask) ; bits 2..0: colour of sprite #1 ; (inverted RGB mask) SPR23COLOURS equ $1FC2 ;(-/W) ; bits 7..6: unused ; bits 5..3: colour of sprite #2 ; (inverted RGB mask) ; bits 2..0: colour of sprite #3 ; (inverted RGB mask) SCORECTRL equ $1FC3 ;(-/W) ; bits 7..2: unused ; bit 1: score format ; 0 = 2 groups of 2 digits ; 1 = 1 group of 4 digits ; bit 0: score position ; 0 = top of screen ; 1 = bottom of screen ; $1FC4..$1FC5: (-/-) unused BGCOLOUR equ $1FC6 ;(-/W) ; bit 7: unused ; bits 6..4: grid colour (normal RGB HB mask) ; bit 3: grid/background enable flag ; (0=off, 1=on) ; bits 2..0: screen colour (normal RGB HB ; mask) (black if bit 3 is clear) PITCH equ $1FC7 ;(-/W) ; bits 7..0: pitch SCORELT equ $1FC8 ;(-/W) left digit pair ; bits 7..4: BCD value of 1st digit ; bits 3..0: BCD value of 2nd digit SCORERT equ $1FC9 ;(-/W) right digit pair ; bits 7..4: BCD value of 3rd digit ; bits 3..0: BCD value of 4th digit BGCOLLIDE equ $1FCA ;(R/-) read-once! ; bit 7: sprite #0 collision with bkgrnd ; bit 6: sprite #1 collision with bkgrnd ; bit 5: sprite #2 collision with bkgrnd ; bit 4: sprite #3 collision with bkgrnd ; bit 3: sprite #0 display complete ; bit 2: sprite #1 display complete ; bit 1: sprite #2 display complete ; bit 0: sprite #3 display complete SPRITECOLLIDE equ $1FCB ;(R/-) read-once! ; bit 7: unused ; bit 6: vertical reset flag ; bit 5: sprites #0/#1 collision ; bit 4: sprites #0/#2 collision ; bit 3: sprites #0/#3 collision ; bit 2: sprites #1/#2 collision ; bit 1: sprites #1/#3 collision ; bit 0: sprites #2/#3 collision P1PADDLE equ $1FCC ;(R/-) cleared at VRST P2PADDLE equ $1FCD ;(R/-) cleared at VRST ; $1FCE..$1FCF ;(-/-) unused ; $1FD0..$1FDF: (*/*) semi-mirror of $1FC0..$1FCF ; $1FE0..$1FEF: (*/*) semi-mirror of $1FC0..$1FCF ; $1FF0..$1FFF: (*/*) semi-mirror of $1FC0..$1FCF ; $2000..$3FFF: (*/*) mirror of $0000..$1FFF ; $4000..$5FFF: (*/*) mirror of $0000..$1FFF ; $6000..$7FFF: (*/*) mirror of $0000..$1FFF R/W: read/write R/-: read-only (write attempts are ignored) -/-: unmapped -/W: write-only */*: mirror (or semi-mirror) (resolve address to ascertain R/W attributes) HB = halfbrite Also, some addresses are read-once (as noted in the text). Note that writes to $1E80..$1EFF affect the NOISE register ($1E80). Reads within this range are handled as shown above. (This applies to both Interton and Elektor.) Vertical and horizontal grid registers are of course usable as ordinary user RAM by games which do not use the grid (such games do not set the "grid/background enable" flag in BGCOLOUR, or set the grid colour to be the same as the screen (background) colour). "The object descriptor areas and background definition range can also be read at all times in the normal way. In the I/O and control section, however, reading data causes that location to be reset to $00." - 2636 PVI datasheet. The Flag pin of the PSU (in the 2650 CPU) controls the paddle interpolation (ie. whether horizontal or vertical). Semi-mirroring: See the Elektor TV Games Computer Coding Guide. Interton BIN Format ------------------- Interton-family BINs are quite straightforward; the size can be up to 6K and these are loaded directly into the corresponding address ($0000..$17FF). The only issue is the fact that the last 512 bytes ($1600..$17FF) is a mirror of $1E00..$1FFF and therefore obscures access to that part of the ROM, limiting the usable size to 5.5K. Since games are not able to be any larger you don't need to worry about CPU page issues because you will only be using the first page anyway. Display Frame ------------- X-axis ("grid" section): 16 character 'columns', each of 8 pixels (each digit requires 2 columns) = 128 pixels. Y-axis ("grid" section): 10 character 'rows', each of 20 pixels = 200 pixels. Internally, the size is 227 "clocks" (X-axis pixels) by 312 rastlines. The complete y-resolution of the Interton VC 4000 is 312 Y-pixels (rastlines), composed as follows for each frame: VRST is on 0.. 19 are 20 "vertical retrace" (above grid but invisible) Y-pixels now VRST is turned off 20.. 39 are 20 "margin" (above grid but visible) Y-pixels 40..239 are 200 "grid" Y-pixels 240..291 are 52 "margin" (below grid but visible) Y-pixels now VRST is turned on 292..311 are 20 "vertical retrace" (below grid but invisible) Y-pixels Thus, the visible Y-region is 272 pixels. The PVI datasheet is wrong to imply that the last raster in which imagery is displayable is 251 (p. 6), ie. 252 visible rasters. Experimental results (eg. Elektor TESTER1) show that at least 268 rasters are visible (perhaps 272?). 4 clock pulses (X-pixels) of the PVI correspond to 1 "fast" cycle of the CPU. 12 clock pulses (X-pixels) of the PVI correspond to 1 "slow" cycle of the CPU. 12 clock pulses (X-pixels) of the PVI correspond to 3 "fast" cycles of the CPU. So, for 227 X-pixels per rastline, there will be 56.75 "fast" CPU cycles per rastline. The complete X-resolution of the Interton VC 4000 is 227 pixels (PVI clocks), composed as follows for each rastline: 0.. 7 are 8 "invisible" (left of visible range) X-pixels 8.. 31 are 24 "margin" (left of grid but visible) X-pixels 32..159 are 128 "grid" X-pixels 160..181 are 22 "margin" (right of grid but visible) X-pixels 182.. ? are ? "invisible" (right of visible range) X-pixels ?..226 are ? "horizontal retrace" X-pixels Thus, the visible region is nominally 174 X-pixels (although the exact value depends on TV magnification, etc.). 227*312 total pixels. 174*272 user-visible pixels. Grid area is 32,20..159,219 (128*200 pixels). According to TinyVCG, CPU speed of Interton and Elektor is 295.574kHz; resolution is 184*268, FPS is 50. Supported machines are vc4000, tvspielc, tvspiel2. "The maximum clock rate of the standard 2650 is 1.25 MHz." - 2650 CPU manual, p. 10. (However, this might be different for 2650A?) 1 "slow" cycle = 2.4 uS. 1 "fast" cycle = 0.8 uS. So, 1,000,000 ÷ 2.4 = 416,666.7 "slow" cycles per second. So, 1,000,000 ÷ 0.8 = 1,500,000 "fast" cycles per second. So, for PAL: 1,500,000 ÷ 50 = 30,000 "fast" cycles per frame. So, for 312 rastlines: 30,000 ÷ 312 = 96.15385 "fast" cycles per rastline. 30,000 ÷ 272 = 110.2941 "fast" cycles per rastline. "Direct instructions require either 2, 3 or 4 ["slow"] processor cycles for execution and therefore vary from 4.8 to 9.6 uS in duration." - 2650 CPU manual, p. 10. 12usec horizontal blank + 52usec visible per line = 64 usec per line. 64 usec per line * 312.5 lines = 20000 usecs (20ms) per frame. In 20ms, we do 17720 cycles. 17720/312.5=56.704 cycles per rastline. Theoretically visible pixels are 0..191, horizontal blank is 192..226, so 192 visible x-pixels (0..191) out of 227. But only 8..181 (174 of them) are typically visible. And the grid only uses $20..$9F (32..159), which is 128 pixels. 4 x-pixels per cycle. So a rastline, with 227 pixels, would take 56.75 cycles. 12 clock pulses (ie. x-pixels) = 1 slow cpu cycles. 12 clock pulses (ie. x-pixels) = 3 fast cpu cycles. That is just over 57 cpu cycles per scanline. Grid ---- Table of bits controlling which segments are lit (addresses are in hexadecimal): 1F80:7 1F80:6 1F80:5 1F80:4 1F80:3 1F80:2 1F80:1 1F80:0 1F81:7 1F81:6 1F81:5 1F81:4 1F81:3 1F81:2 1F81:1 1F81:0 row 0 set 1 (raster 20) 1F80:7 1F80:6 1F80:5 1F80:4 1F80:3 1F80:2 1F80:1 1F80:0 1F81:7 1F81:6 1F81:5 1F81:4 1F81:3 1F81:2 1F81:1 1F81:0 row 1 set 1 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 2 set 2a 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 3 set 2a 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 4 set 2a 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 5 set 2a 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 6 set 2a 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 7 set 2a 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 8 set 2a 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 9 set 2a 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 10 set 2a 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 11 set 2b 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 12 set 2b 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 13 set 2b 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 14 set 2b 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 15 set 2b 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 16 set 2b 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 17 set 2b 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 18 set 2b 1F82:7 1F82:6 1F82:5 1F82:4 1F82:3 1F82:2 1F82:1 1F82:0 1F83:7 1F83:6 1F83:5 1F83:4 1F83:3 1F83:2 1F83:1 1F83:0 row 19 set 2b : : : 1FA4:7 1FA4:6 1FA4:5 1FA4:4 1FA4:3 1FA4:2 1FA4:1 1FA4:0 1FA5:7 1FA5:6 1FA5:5 1FA5:4 1FA5:3 1FA5:2 1FA5:1 1FA5:0 row 180 set 19 1FA4:7 1FA4:6 1FA4:5 1FA4:4 1FA4:3 1FA4:2 1FA4:1 1FA4:0 1FA5:7 1FA5:6 1FA5:5 1FA5:4 1FA5:3 1FA5:2 1FA5:1 1FA5:0 row 181 set 19 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 182 set 20a 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 183 set 20a 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 184 set 20a 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 185 set 20a 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 186 set 20a 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 187 set 20a 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 188 set 20a 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 189 set 20a 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 190 set 20a 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 191 set 20b 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 192 set 20b 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 193 set 20b 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 194 set 20b 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 195 set 20b 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 196 set 20b 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 197 set 20b 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 198 set 20b 1FA6:7 1FA6:6 1FA6:5 1FA6:4 1FA6:3 1FA6:2 1FA6:1 1FA6:0 1FA7:7 1FA7:6 1FA7:5 1FA7:4 1FA7:3 1FA7:2 1FA7:1 1FA7:0 row 199 set 20b (raster 219) Table of bits controlling segment widths: $1FA8:7..6: %00 or %10 = 1x width for sets 1.. 4 (except where overridden by $1FA8:5..0) %01 = 2x width for sets 1.. 4 (except where overridden by $1FA8:5..0) %11 = 4x width for sets 1.. 4 (except where overridden by $1FA8:5..0) $1FA8:5: %0 = 1x/2x/4x width for set 4b (depending on $1FA8:7..6) %1 = 8x width for set 4b $1FA8:4: %0 = 1x/2x/4x width for set 4a (depending on $1FA8:7..6) %1 = 8x width for set 4a $1FA8:3: %0 = 1x/2x/4x width for set 3 (depending on $1FA8:7..6) %1 = 8x width for set 3 $1FA8:2: %0 = 1x/2x/4x width for set 2b (depending on $1FA8:7..6) %1 = 8x width for set 2b $1FA8:1: %0 = 1x/2x/4x width for set 2a (depending on $1FA8:7..6) %1 = 8x width for set 2a $1FA8:0: %0 = 1x/2x/4x width for set 1 (depending on $1FA8:7..6) %1 = 8x width for set 1 : : : $1FAC:7..6: %00 or %10 = 1x width for sets 17..20 (except where overridden by $1FAC:5..0) %01 = 2x width for sets 17..20 (except where overridden by $1FAC:5..0) %11 = 4x width for sets 17..20 (except where overridden by $1FAC:5..0) $1FAC:5: %0 = 1x/2x/4x width for set 20b (depending on $1FAC:7..6) %1 = 8x width for set 20b $1FAC:4: %0 = 1x/2x/4x width for set 20a (depending on $1FAC:7..6) %1 = 8x width for set 20a $1FAC:3: %0 = 1x/2x/4x width for set 19 (depending on $1FAC:7..6) %1 = 8x width for set 19 $1FAC:2: %0 = 1x/2x/4x width for set 18b (depending on $1FAC:7..6) %1 = 8x width for set 18b $1FAC:1: %0 = 1x/2x/4x width for set 18a (depending on $1FAC:7..6) %1 = 8x width for set 18a $1FAC:0: %0 = 1x/2x/4x width for set 17 (depending on $1FAC:7..6) %1 = 8x width for set 17 Tones ----- Here are the optimal PITCH register values for harmonic melodies, in hexadecimal and decimal notations: Note PITCH reg Actual Freq Ideal Freq ---------- $FF (255) 30.75781 Hz ----------- xxlow B : $FE (254) 30.87843 Hz 30.868 Hz ---------- $FD (253) 31.00000 Hz ----------- ---------- $FC (252) 31.12253 Hz ----------- ---------- $FB (251) 31.24603 Hz ----------- ---------- $FA (250) 31.37052 Hz ----------- ---------- $F9 (249) 31.49600 Hz ----------- ---------- $F8 (248) 31.62249 Hz ----------- ---------- $F7 (247) 31.75000 Hz ----------- ---------- $F6 (246) 31.87854 Hz ----------- ---------- $F5 (245) 32.00813 Hz ----------- ---------- $F4 (244) 32.13877 Hz ----------- ---------- $F3 (243) 32.27049 Hz ----------- ---------- $F2 (242) 32.40329 Hz ----------- ---------- $F1 (241) 32.53719 Hz ----------- xlow C : $F0 (240) 32.67220 Hz 32.703 Hz ---------- $EF (239) 32.80833 Hz ----------- ---------- $EE (238) 32.94561 Hz ----------- ---------- $ED (237) 33.08403 Hz ----------- ---------- $EC (236) 33.22363 Hz ----------- ---------- $EB (235) 33.36441 Hz ----------- ---------- $EA (234) 33.50638 Hz ----------- ---------- $E9 (233) 33.64957 Hz ----------- ---------- $E8 (232) 33.79399 Hz ----------- ---------- $E7 (231) 33.93966 Hz ----------- ---------- $E6 (230) 34.08658 Hz ----------- ---------- $E5 (229) 34.23478 Hz ----------- ---------- $E4 (228) 34.38428 Hz ----------- ---------- $E3 (227) 34.53509 Hz ----------- xlow C#: $E2 (226) 34.68723 Hz 34.648 Hz ---------- $E1 (225) 34.84071 Hz ----------- ---------- $E0 (224) 34.99556 Hz ----------- ---------- $DF (223) 35.15179 Hz ----------- ---------- $DE (222) 35.30942 Hz ----------- ---------- $DD (221) 35.46847 Hz ----------- ---------- $DC (220) 35.62896 Hz ----------- ---------- $DB (219) 35.79091 Hz ----------- ---------- $DA (218) 35.95434 Hz ----------- ---------- $D9 (217) 36.11927 Hz ----------- ---------- $D8 (216) 36.28571 Hz ----------- ---------- $D7 (215) 36.45370 Hz ----------- xlow D : $D6 (214) 36.62326 Hz 36.708 Hz ---------- $D5 (213) 36.79439 Hz ----------- ---------- $D4 (212) 36.96714 Hz ----------- ---------- $D3 (211) 37.14151 Hz ----------- ---------- $D2 (210) 37.31754 Hz ----------- ---------- $D1 (209) 37.49524 Hz ----------- ---------- $D0 (208) 37.67464 Hz ----------- ---------- $CF (207) 37.85577 Hz ----------- ---------- $CE (206) 38.03865 Hz ----------- ---------- $CD (205) 38.22330 Hz ----------- ---------- $CC (204) 38.40976 Hz ----------- ---------- $CB (203) 38.59804 Hz ----------- ---------- $CA (202) 38.78818 Hz ----------- xlow D#: $C9 (201) 38.98020 Hz 38.891 Hz ---------- $C8 (200) 39.17413 Hz ----------- ---------- $C7 (199) 39.37000 Hz ----------- ---------- $C6 (198) 39.56784 Hz ----------- ---------- $C5 (197) 39.76768 Hz ----------- ---------- $C4 (196) 39.96954 Hz ----------- ---------- $C3 (195) 40.17347 Hz ----------- ---------- $C2 (194) 40.37949 Hz ----------- ---------- $C1 (193) 40.58763 Hz ----------- ---------- $C0 (192) 40.79793 Hz ----------- ---------- $BF (191) 41.01042 Hz ----------- xlow E : $BE (190) 41.22513 Hz 41.203 Hz ---------- $BD (189) 41.44210 Hz ----------- ---------- $BC (188) 41.66138 Hz ----------- ---------- $BB (187) 41.88298 Hz ----------- ---------- $BA (186) 42.10695 Hz ----------- ---------- $B9 (185) 42.33333 Hz ----------- ---------- $B8 (184) 42.56216 Hz ----------- ---------- $B7 (183) 42.79348 Hz ----------- ---------- $B6 (182) 43.02732 Hz ----------- ---------- $B5 (181) 43.26374 Hz ----------- ---------- $B4 (180) 43.50276 Hz ----------- xlow F : $B3 (179) 43.74445 Hz 43.654 Hz ---------- $B2 (178) 43.98883 Hz ----------- ---------- $B1 (177) 44.23595 Hz ----------- ---------- $B0 (176) 44.48587 Hz ----------- ---------- $AF (175) 44.73864 Hz ----------- ---------- $AE (174) 44.99429 Hz ----------- ---------- $AD (173) 45.25287 Hz ----------- ---------- $AC (172) 45.51445 Hz ----------- ---------- $AB (171) 45.77907 Hz ----------- ---------- $AA (170) 46.04678 Hz ----------- xlow F#: $A9 (169) 46.31765 Hz 46.249 Hz ---------- $A8 (168) 46.59172 Hz ----------- ---------- $A7 (167) 46.86905 Hz ----------- ---------- $A6 (166) 47.14970 Hz ----------- ---------- $A5 (165) 47.43373 Hz ----------- ---------- $A4 (164) 47.72121 Hz ----------- ---------- $A3 (163) 48.01220 Hz ----------- ---------- $A2 (162) 48.30675 Hz ----------- ---------- $A1 (161) 48.60494 Hz ----------- xlow G : $A0 (160) 48.90683 Hz 48.999 Hz ---------- $9F (159) 49.21250 Hz ----------- ---------- $9E (158) 49.52201 Hz ----------- ---------- $9D (157) 49.83544 Hz ----------- ---------- $9C (156) 50.15287 Hz ----------- ---------- $9B (155) 50.47436 Hz ----------- ---------- $9A (154) 50.80000 Hz ----------- ---------- $99 (153) 51.12987 Hz ----------- ---------- $98 (152) 51.46405 Hz ----------- xlow G#: $97 (151) 51.80263 Hz 51.913 Hz ---------: $96 (150) 52.14569 Hz ----------- ---------: $95 (149) 52.49333 Hz ----------- ---------: $94 (148) 52.84564 Hz ----------- ---------: $93 (147) 53.20270 Hz ----------- ---------: $92 (146) 53.56462 Hz ----------- ---------: $91 (145) 53.93151 Hz ----------- ---------: $90 (144) 54.30345 Hz ----------- ---------: $8F (143) 54.68056 Hz ----------- xlow A : $8E (142) 55.06294 Hz 55.000 Hz ---------: $8D (141) 55.45070 Hz ----------- ---------: $8C (140) 55.84397 Hz ----------- ---------: $8B (139) 56.24286 Hz ----------- ---------: $8A (138) 56.64748 Hz ----------- ---------: $89 (137) 57.05797 Hz ----------- ---------: $88 (136) 57.47445 Hz ----------- ---------: $87 (135) 57.89706 Hz ----------- xlow A#: $86 (134) 58.32593 Hz 58.270 Hz ---------: $85 (133) 58.76119 Hz ----------- ---------: $84 (132) 59.20301 Hz ----------- ---------: $83 (131) 59.65152 Hz ----------- ---------: $82 (130) 60.10687 Hz ----------- ---------: $81 (129) 60.56923 Hz ----------- ---------: $80 (128) 61.03876 Hz ----------- ---------- $7F (127) 61.52 Hz ----------- ---------- $7E (126) 62.00 Hz ----------- ---------- $7D (125) 62.49 Hz ----------- xlow B : $7C (124) 62.99 Hz 61.735 Hz ---------- $7B (123) 63.50 Hz ----------- ---------- $7A (122) 64.02 Hz ----------- ---------- $79 (121) 64.54 Hz ----------- ---------- $78 (120) 65.07 Hz ----------- vlow C : $77 (119) 65.62 Hz 65.406 Hz ---------- $76 (118) 66.17 Hz ----------- ---------- $75 (117) 66.73 Hz ----------- ---------- $74 (116) 67.30 Hz ----------- ---------- $73 (115) 67.88 Hz ----------- ---------- $72 (114) 68.47 Hz ----------- ---------- $71 (113) 69.07 Hz ----------- vlow C#: $70 (112) 69.68 Hz 69.296 Hz ---------- $6F (111) 70.30 Hz ----------- ---------- $6E (110) 70.94 Hz ----------- ---------- $6D (109) 71.58 Hz ----------- ---------- $6C (108) 72.24 Hz ----------- vlow D : $6B (107) 72.91 Hz 73.416 Hz ---------- $6A (106) 73.59 Hz ----------- ---------- $69 (105) 74.28 Hz ----------- ---------- $68 (104) 74.99 Hz ----------- ---------- $67 (103) 75.71 Hz ----------- ---------- $66 (102) 76.45 Hz ----------- ---------- $65 (101) 77.20 Hz ----------- vlow D#: $64 (100) 77.96 Hz 77.782 Hz ---------- $63 ( 99) 78.74 Hz ----------- ---------- $62 ( 98) 79.54 Hz ----------- ---------- $61 ( 97) 80.35 Hz ----------- ---------- $60 ( 96) 81.18 Hz ----------- vlow E : $5F ( 95) 82.02 Hz 82.407 Hz ---------- $5E ( 94) 82.88 Hz ----------- ---------- $5D ( 93) 83.77 Hz ----------- ---------- $5C ( 92) 84.67 Hz ----------- ---------- $5B ( 91) 85.59 Hz ----------- ---------- $5A ( 90) 86.53 Hz ----------- vlow F : $59 ( 89) 87.49 Hz 87.307 Hz ---------- $58 ( 88) 88.47 Hz ----------- ---------- $57 ( 87) 89.48 Hz ----------- ---------- $56 ( 86) 90.51 Hz ----------- ---------- $55 ( 85) 91.56 Hz ----------- vlow F#: $54 ( 84) 92.64 Hz 92.499 Hz ---------- $53 ( 83) 93.74 Hz ----------- ---------- $52 ( 82) 94.87 Hz ----------- ---------- $51 ( 81) 96.02 Hz ----------- ---------- $50 ( 80) 97.21 Hz ----------- vlow G : $4F ( 79) 98.42 Hz 97.999 Hz ---------- $4E ( 78) 99.67 Hz ----------- ---------- $4D ( 77) 100.95 Hz ----------- ---------- $4C ( 76) 102.26 Hz ----------- vlow G#: $4B ( 75) 103.61 Hz 103.826 Hz ---------- $4A ( 74) 104.99 Hz ----------- ---------- $49 ( 73) 106.41 Hz ----------- ---------- $48 ( 72) 107.86 Hz ----------- ---------- $47 ( 71) 109.36 Hz ----------- vlow A : $46 ( 70) 110.90 Hz 110.000 Hz ---------- $45 ( 69) 112.49 Hz ----------- ---------- $44 ( 68) 114.12 Hz ----------- ---------- $43 ( 67) 115.79 Hz ----------- vlow A#: $42 ( 66) 117.52 Hz 116.541 Hz ---------- $41 ( 65) 119.30 Hz ----------- ---------- $40 ( 64) 121.14 Hz ----------- vlow B : $3F ( 63) 123.03 Hz 123.471 Hz ---------- $3E ( 62) 124.98 Hz ----------- ---------- $3D ( 61) 127.00 Hz ----------- ---------- $3C ( 60) 129.08 Hz ----------- low C : $3B ( 59) 131.23 Hz 130.813 Hz ---------- $3A ( 58) 133.46 Hz ----------- ---------- $39 ( 57) 135.76 Hz ----------- low C#: $38 ( 56) 138.14 Hz 138.591 Hz ---------- $37 ( 55) 140.61 Hz ----------- ---------- $36 ( 54) 143.16 Hz ----------- low D : $35 ( 53) 145.81 Hz 146.832 Hz ---------- $34 ( 52) 148.57 Hz ----------- ---------- $33 ( 51) 151.42 Hz ----------- ---------- $32 ( 50) 154.39 Hz ----------- low D#: $31 ( 49) 157.48 Hz 155.563 Hz ---------- $30 ( 48) 160.69 Hz ----------- low E : $2F ( 47) 164.04 Hz 164.814 Hz ---------- $2E ( 46) 167.53 Hz ----------- ---------- $2D ( 45) 171.17 Hz ----------- low F : $2C ( 44) 174.98 Hz 174.614 Hz ---------- $2B ( 43) 178.95 Hz ----------- low F#: $2A ( 42) 183.12 Hz 184.997 Hz ---------- $29 ( 41) 187.48 Hz ----------- ---------- $28 ( 40) 192.05 Hz ----------- low G : $27 ( 39) 196.85 Hz 195.998 Hz ---------- $26 ( 38) 201.90 Hz ----------- low G#: $25 ( 37) 207.21 Hz 207.652 Hz ---------- $24 ( 36) 212.81 Hz ----------- low A : $23 ( 35) 218.72 Hz 220.000 Hz ---------- $22 ( 34) 224.97 Hz ----------- low A#: $21 ( 33) 231.59 Hz 233.082 Hz ---------- $20 ( 32) 238.61 Hz ----------- low B : $1F ( 31) 246.06 Hz 246.942 Hz ---------- $1E ( 30) 254.00 Hz ----------- middle C : $1D ( 29) 262.47 Hz 261.626 Hz ---------- $1C ( 28) 271.52 Hz ----------- middle C#: $1B ( 27) 281.21 Hz 277.183 Hz middle D : $1A ( 26) 291.63 Hz 293.665 Hz ---------- $19 ( 25) 302.84 Hz ----------- middle D#: $18 ( 24) 314.96 Hz 311.127 Hz middle E : $17 ( 23) 328.08 Hz 329.628 Hz ---------- $16 ( 22) 342.35 Hz ----------- middle F : $15 ( 21) 357.91 Hz 349.228 Hz middle F#: $14 ( 20) 374.95 Hz 369.994 Hz middle G : $13 ( 19) 393.70 Hz 391.995 Hz middle G#: $12 ( 18) 414.42 Hz 415.305 Hz middle A : $11 ( 17) 437.44 Hz 440.000 Hz middle A#: $10 ( 16) 463.18 Hz 466.164 Hz middle B : $0F ( 15) 492.12 Hz 493.883 Hz high C : $0E ( 14) 524.93 Hz 523.251 Hz high C#: $0D ( 13) 562.43 Hz 554.365 Hz high D : -------------------------- 587.330 Hz high D#: $0C ( 12) 605.69 Hz 622.254 Hz high E : $0B ( 11) 656.17 Hz 659.255 Hz high F : $0A ( 10) 715.82 Hz 698.456 Hz high F#: -------------------------- 739.989 Hz high G : $09 ( 9) 787.40 Hz 783.991 Hz high G#: -------------------------- 830.609 Hz high A : $08 ( 8) 874.89 Hz 880.000 Hz high A#: -------------------------- 932.328 Hz high B : $07 ( 7) 984.25 Hz 987.767 Hz vhigh C : -------------------------- 1046.502 Hz vhigh C#: $06 ( 6) 1124.86 Hz 1108.731 Hz vhigh D : -------------------------- 1174.659 Hz vhigh D#: -------------------------- 1244.508 Hz vhigh E : $05 ( 5) 1312.33 Hz 1318.510 Hz vhigh F : -------------------------- 1396.913 Hz vhigh F#: -------------------------- 1479.978 Hz vhigh G : $04 ( 4) 1574.80 Hz 1567.982 Hz vhigh G#: -------------------------- 1661.219 Hz middle G : $03 ( 3) 1968.50 Hz ----------- high C : $02 ( 2) 2624.67 Hz ----------- high G : $01 ( 1) 3937.00 Hz ----------- silence: $00 ( 0) ------------- ----------- This should assist in illustrating why tones are off-key. Strange results for the higher-pitched notes (3..1) are due to aliasing effects, which might be absent on the genuine console. The algorithm for tone generation is: frequency = 7874 ÷ (PITCH + 1); Noise ----- The following code fragments are given in the "TV Games Computer" book, p. 187: ;"sound off" ;NOISE = 0; eorz r0 stra,r0 NOISE ;"sound off" ;NOISE = 0; lodi,r0 0 stra,r0 NOISE ;"PVI sound on" ;NOISE = 4; lodi,r0 4 stra,r0 NOISE ;"noise on" ;NOISE = $10; lodi,r0 $10 stra,r0 NOISE Colours ------- R,G,B ----- 0: black 0,0,0 Colours 0..7 are fullbrite (FB). 1: blue 0,0,2 2: green 0,2,0 3: cyan 0,2,2 4: red 2,0,0 5: purple 2,0,2 6: yellow 2,2,0 7: white 2,2,2 8: "dark black" (black) 0,0,0 Colours 8..15 are halfbrite (HB); 9: dark blue 0,0,1 they are approximately half as 10: dark green 0,1,0 bright as the corresponding 11: dark cyan 0,1,1 fullbrite colours (0..7). 12: dark red 1,0,0 13: dark purple 1,0,1 14: "dark yellow" (brown) 1,1,0 15: "dark white" (grey ) 1,1,1 RGB values of 0: zero intensity 1: half intensity (approx?) 2: full intensity Background colour is: 8 + (bits 2..0 of BGCOLOUR ) (ie. 8..15) Grid colour is: 8 + ((bits 6..4 of BGCOLOUR ) >> 4) (ie. 8..15) Digit colours are: 7 - ((bits 6..4 of BGCOLOUR ) >> 4) (ie. 0.. 7) Sprite #0 colours are: 7 - ((bits 5..3 of SPR01COLOURS) >> 3) (ie. 0.. 7) Sprite #1 colours are: 7 - (bits 2..0 of SPR01COLOURS) (ie. 0.. 7) Sprite #2 colours are: 7 - ((bits 5..3 of SPR23COLOURS) >> 3) (ie. 0.. 7) Sprite #3 colours are: 7 - (bits 2..0 of SPR23COLOURS) (ie. 0.. 7) The digit colour is always dependent on the grid colour, and vice versa, as shown: BGCOLOUR Grid Digits %x000xxxx black white %x001xxxx dark blue yellow %x010xxxx dark green purple %x011xxxx dark cyan red %x100xxxx dark red cyan %x101xxxx dark purple green %x110xxxx brown blue %x111xxxx grey black Note that some Interton VC 4000 family members, such as the Fountain, apparently use fullbrite mode rather than halfbrite mode. See the Elektor TV Games Computer Coding Guide for information about fullbrite mode. Digits ------ Each digit is 12*20 pixels. Digit Y-area is 20..39 and/or 200..219, depending on SCORECTRL. 1st digit X-area is 60.. 71. 2nd digit X-area is 76.. 87. 3rd digit X-area is 92..103 or 108..119, depending on SCORECTRL. 4th digit X-area is 108..119 or 124..135, depending on SCORECTRL. Sprites ------- SPRITEnAX: "If SPRITEnAX is changed during the time that the corresponding object video is being displayed, the portion of the object not yet displayed will be displaced to the new horizontal position." Ie. it is resampled every pixel (at least whilst the sprite is being displayed). SPRITEnAY: "The value of SPRITEnAY is 'remembered' at the trailing edge of VRST. Thus, if SPRITEnAY is changed during the active scan, the vertical object position change will not be effective until the next active scan." Ie. it is sampled once per frame (at the end of vertical blank). SPRITEnBY is when to redraw (reuse) the sprite: $FF means 0 rastlines gap $00 means 1 rastline gap $01 means 2 rastlines gap $02 means 3 rastlines gap $FC means 253 rastlines gap $FD means "never" (but this register will still be reexamined each rastline?) $FE means "never" (but this register will still be reexamined each rastline?) According to the 2636 PVI datasheet: Sprite X = SPRITEAXn + 1 (assuming leftmost clock is 0) Sprite Y = SPRITEAYn + 1 (assuming topmost raster is 0) SPRITEAXn of >= 228 is not displayed. SPRITEAYn of >= 253 is not displayed. SPRITEAXn is not cached (or is cached during HRST). SPRITEAYn must be changed by (ie. it is cached at) the end of VRST. SPRITEBXn is cached during HRST. SPRITEBY is sampled just prior to displaying the last line of the (original or duplicate) object. That sampling presumably wouldn't affect the last line itself. "The interrupt generation occurs during the horizontal sync at the end of the last line of the sprite display." - Manfred Schneider. SIZES is as follows: two bits per sprite (#3,#2,#1,#0): bits 7..6: sprite #3 size bits 5..4: sprite #2 size bits 3..2: sprite #1 size bits 1..0: sprite #0 size %00 = 1x size ( 8*10 pixels) %01 = 2x size (16*20 pixels) %10 = 4x size (32*40 pixels) %11 = 8x size (64*80 pixels) Timing ------ 1 "long" cycle (3 "short" cycles) requires 3.38uS (microseconds). So, in 1 second, approx. 295,856.9781484442 (1,000,000/3.38) "long" cycles can be executed. So, in 1 frame (1/50 of a second), approx. 5,917.16 "long" cycles can be executed. So, in 1 raster (1/312 of a frame), approx. 18.96526 "long" cycles (approx. 56.89576502854696 "short" cycles) can be executed. "There are a total of 262 scan lines: 192 in the active display, 38 before and 32 after. The PVI uses a 3.579545 MHz crystal. This frequency, divided by 4, is used to clock the CPU. Thus, during a screen scan line 56.75 CPU cycles occur. Rounding this value to 57, some games cease to work." - Lance Squire. Common Misconceptions --------------------- There are many inaccuracies which have become widely believed. These will now be corrected: * The Interton VC 4000 was supposedly made from 1974 but not sold until 1978. However, the Signetics 2650 CPU was only made from 1975; therefore, the Interton VC 4000 could not have been made from 1974. * There are 16 colours, not 9. * There are no multicoloured sprites. All sprites are single-colour (although the same effect can of course be achieved by superimposing multiple sprites on the screen). 2636 PVI Datasheet Example -------------------------- SPRITE1AX = 42 SPRITE1AY = 36 SPRITE1BX = 30 SPRITE1BY = 9 (10 line gap) Sprite #1 ( original) is shown at 42..49, 36.. 45. Sprite #1 ( 1st dup.) is shown at 30..37, 56.. 65. Sprite #1 ( 2nd dup.) is shown at 30..37, 76.. 85. Sprite #1 ( 3rd dup.) is shown at 30..37, 96..105. Sprite #1 ( 4th dup.) is shown at 30..37,116..125. Sprite #1 ( 5th dup.) is shown at 30..37,136..145. Sprite #1 ( 6th dup.) is shown at 30..37,156..165. Sprite #1 ( 7th dup.) is shown at 30..37,176..185. Sprite #1 ( 8th dup.) is shown at 30..37,196..205. Sprite #1 ( 9th dup.) is shown at 30..37,216..225. Sprite #1 (10th dup.) is shown at 30..37,236..245. Either 250 or 251 is the last displayable rastline. SPRITE2AX = 62 SPRITE2AY = 20 SPRITE2BX = 88 SPRITE2BY = 27 (28 line gap) Sprite #2 ( original) is shown at 62..69, 20.. 29. Sprite #2 ( 1st dup.) is shown at 88..95, 58.. 67. Sprite #2 ( 2nd dup.) is shown at 88..95, 96..105. Sprite #2 ( 3rd dup.) is shown at 88..95,134..143. Sprite #2 ( 4th dup.) is shown at 88..95,172..181. Sprite #2 ( 5th dup.) is shown at 88..95,210..219. Sprite #2 ( 6th dup.) is shown at 88..95,248..250/251? Unresolved PVI Questions ------------------------ The primary remaining obstacles to good Interton/Elektor emulation seem to be sprite subsystem (especially duplicate sprite handling), and/or display frame/timing issues. The documentation contains ambiguous and seemingly contradictory statements. Terminological note: a new "sprite line" occurs whenever a new row of sprite imagery is fetched, and thus occurs every rastline when the sprite is drawn at 1x size, every second rastline when drawn at 2x size, etc. When is SIZES ($1FC0) read by the PVI? eg. start of sprite, or each rastline, or each sprite line. Definitely not start of frame. Start of sprite helps HUNTING/SHOOTGAL. Each rastline helps INVADERA/INVADERB? What is the last X-position at which a sprite can be positioned (ie. started, ie. 1st clock drawn)? What is the last Y-position at which a sprite can be positioned (ie. started, ie. 1st raster drawn)? What is the last X-position at which a sprite column can be drawn? What is the last Y-position at which a sprite row can be drawn? "A 'primary' sprite can start at any line up to 255 (maximum value in SPRITEAYn), a duplicate sprite also beyond that line and until VRST goes active." - Manfred Schneider. Improves GRNDPRIX/CARRACES. "If SPRITEAYn is set to >252, the object is effectively removed from the video field." - 2636 PVI datasheet, p. 5. But that seems to be wrong? Resolved PVI Questions ---------------------- 1. Are mid-sprite changes to SPRITEnAX effective? (TESTER2.PGM confirms that they are.) "If SPRITEnAX is changed during the time that the corresponding object video is being displayed, the portion of the object not yet displayed will be displaced to the new horizontal position." - PVI manual, p. 5. "Unlike SPRITEnAX and SPRITEnAY, SPRITEnBX and SPRITEnBY may be changed during the scan and such changes will be effected on the current scan." - PVI manual, p. 5. The first statement is correct. The second statement should be amended to "Unlike SPRITEnAY, SPRITEnBX and SPRITEnBY may be changed during the scan and such changes will be effected on the current scan." 2. How do sprite coordinates relate to eg. grid coordinates? eg. SPRITEnAX=31,SPRITEnAY=19 is top left of grid (according to 2636 PVI datasheet, p. 5) or is above and to the left of the top left grid (according to 2636 PVI datasheet, p. 6) SPRITEnAY = $FF aligns the sprite to raster 0 SPRITEnAY = $00 aligns the sprite to raster 1 SPRITEnAY = $01 aligns the sprite to raster 2 etc. This is demonstrated by eg. Interton BLACKJAC. Chips ----- The Come-Frutas game uses these chips: Texas Instrument TMS2114L-45NL BP8109 (x2) These are 1K 4-bit RAM chips. 2 wired together make 1K of 8-bit RAM. Texas Instrument sn74ls10n-10 NAND gates (glue logic) National Semiconductor (NSC) SP8323* DM74LS04N hex inverting gates (glue logic) NEC D2732D 8335PX052 4K 8-bit EPROM END OF DOCUMENT-----------------------------------------------------------