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The Genesis/Megadrive contained a relatively powerful display processor (for the time), otherwise known as the VDP. This occupied position IC-8 on the circuit board, and is numbered 315-5313.

1SD0Display RAM Data 0-65CD1068K Data 10
2SD1Display RAM Data 1-66CD1168K Data 11
3SD1Display RAM Data 2-67CD1268K Data 12
4SD1Display RAM Data 3-68CD1368K Data 13
5SD1Display RAM Data 4-69CD1468K Data 14
6SD1Display RAM Data 5-70CD1568K Data 15
7SD1Display RAM Data 6-71CA068K Address 1
8SD1Display RAM Data 7-72CA168K Address 2
9-Unknown-73CA268K Address 3
10!SE 0Display RAM !SOE-74CA368K Address 4
11SCDisplay RAM SC-75CA468K Address 5
12!RASDisplay RAM !RAS-76CA568K Address 6
13!CASDisplay RAM !CAS-77CA668K Address 7
14-Unknown-78CA768K Address 8
15!WEDisplay RAM !WE-79CA868K Address 9
16!OE 1Display RAM !DT/!OE-80CA968K Address 10
17GNDGround-81CA1068K Address 11
18-Unknown-82CA1168K Address 12
19-Unknown-83CA1268K Address 13
20-Unknown-84CA1368K Address 14
21-Unknown-85CA1468K Address 15
22-Unknown-86CA1568K Address 16
23-Unknown-87CA1668K Address 17
24-Unknown-88CA1768K Address 18
25-Unknown-89CA1868K Address 19
26AGCAnalog Ground-90CA1968K Address 20
27RRed output-91CA2068K Address 21
28GGreen output-92CA2168K Address 22
29BBlue output-93CA2268K Address 23
30AVCAnalog video supply voltage-94AVSAnalog sound supply voltage
31AD0Display RAM Address 0-95PSGPSG Sound output
32AVCDisplay RAM Address 1-96AGSAnalog sound ground
33AVCDisplay RAM Address 2-97GNDGround
34AVCDisplay RAM Address 3-98!INTZ80 Interrupt
35AVCDisplay RAM Address 4-99!BR68K !BR
36AVCDisplay RAM Address 5-100!BGAK68K !BGACK
37AVCDisplay RAM Address 6-101!BG68K !BG
38AVCDisplay RAM Address 7-102!MRE0Bus Arbiter !VDPN
39!YSVideo?-103!BG68K !BG
40SPA/BPulled up to VCC1-104!IPL168K !IPL1 (Interrupt)
41!VSYNCVSync to Bus Arbiter-105!IPL268K !IPL2 (Interrupt)
42!C-SYNCComposite Sync to encoder-106!IREQZ80 IREQ
43!HSYNCHSync to Bus Arbiter-107!RDZ80 !RD
44!HL68K Halt?-108!WRZ80 !WR
45SEL0!M3-109!MIZ80 !MI
46!PALNTSC flag input-110!AS68K !AS
48SELIPulled down to GND-112!LDS68K !LDS
49!CLKI68K Clock out-113R/!W68K Read/!Write
51CLK0Z80 Clock out-115!UWR68K memory !UWR
52MCLKMaster Clock in-116!LWR68K memory !LWR
53EDCKHS_CLK in-117!OE068K memory !OE0
54VDDVCC1-118!CAS068K memory !CAS0
55CD068K Data 0-119!RAS068K memory !RAS0
56CD168K Data 1-120-Unknown
57CD268K Data 2-121-Unknown
58CD368K Data 3-122-Unknown
59CD468K Data 4-123-Unknown
60CD568K Data 5-124-Unknown
61CD668K Data 6-125-Unknown
62CD768K Data 7-126-Unknown
63CD868K Data 8-127-Unknown
64CD968K Data 9-128VDDVCC1

Oddities with the way that memory is connected to the VDP means that the local V-RAM chips are split across a dedicated data bus and a shared data/address bus. I'm not sure why this is!

schematics/megadrive1vdppinout.txt · Last modified: 2019/08/27 20:45 by