Allow me to share the following bus interchanges & terminals which was in operation back in 1985. The interchanges & terminals will be divided into 4 main areas: East, South, West & North.
East
Upper Changi Terminal - Services 80, 81

Somapah Terminal - Services 11, 12, 14, 155

Tampines Terminal - Services 10, 23, 28, 31, 292, 293, 294

Bedok Interchange - Services 3, 4, 7, 8, 18, 25, 26, 30, 32, 41, 152, 207, 221, 222, 225, 226, 227, 228, 229

Chai Chee Terminal - Services 13, 20, 33, 40, 44, 158, 220, 221C, 223, 224, 401

Marine Parade Terminal - Services 16, 135, 196, 211, 213

Jalan Eunos Terminal - Services 50, 51

Upper Serangoon Terminal - Services 84, 136, 153

Hougang Interchange - Services 85, 97, 111, 321, 323, 329

MacPherson Terminal - Services 61, 62, 64, 65, 154

Sims Place Terminal - Services 94, 198

Geylang Terminal - Services 5, 9, 71, 91, 197

Punggol Terminal - Services 82, 83

Changi Village Terminal - Services 1, 2, 210, 218

Changi Airport PTB Terminal - Service 390
South
Crawford Terminal - 150, 160, 181, 195, 209

Queen Street Terminal - Services 170, 171

Potong Pasir Terminal - Services 142, 147

St Michaels Terminal - Services 120, 122, 123, 124, 125, 126

Toa Payoh Interchange - Services 73, 137, 139, 140, 141, 142, 143, 145, 146, 148, 149, 150, 151, 152, 155, 157, 158, 159, 231, 232, 235, 237, 238, 239

South Canal Terminal - Services 55, 192, 194

Prince Edward Terminal - Services 60, 70, 80, 82, 130, 131, 161, 172, 175, 186, 193

New Bridge Road Terminal - Services 11, 81, 83, 101, 134, 164, 173, 174, 182, 183

Delta Terminal - Service 1

Redhill Terminal - Service 41

Rumah Tinggi Terminal - Service 62

Lower Delta Terminal - Services 65, 195

Bukit Merah Interchange - Services 14, 16, 44, 50, 125, 132, 139, 153, 184, 271, 272, 273, 274, 275, 850, 851

World Trade Centre Terminal - Services 84, 93, 100, 163, 167, 180, CBD1

Labrador Terminal - Services 51, 166, 215

Commonwealth Drive Terminal - Service 203

Buona Vista Terminal - Services 2, 12, 57, 90, 103, 106, 111, 112, 148, 189, 212

Ghim Moh Terminal - Services 13, 20
West
Bukit Timah Terminal - Services 5, 177, 202

Ulu Pandan Terminal - Services 61, 188

Kent Ridge Terminal - Services 33, 145, 200, 201, 216

Clementi Interchange - Services 74, 75, 76, 92, 95, 96, 146, 186, 205, 209, 282, 284, 285, 287

Princess Elizabeth Terminal - Services 173, 193

Bukit Batok Terminal - Services 122, 361, 366, 367

Jurong East Terminal - Services 7, 97, 98, 147, 333, 334, 335

Jurong Depot Terminal - Service 143

Boon Lay Terminal - Services 247A, 249A, 250A, 251A

NTU Terminal - Service 174

Jurong Interchange - Services 10, 30, 98, 154, 157, 165, 178, 183, 184, 192, 196, 197, 198, 199, 206, 240, 241, 242, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 257, 406, 450

Tuas Terminal - Service 175

Lim Chu Kang Terminal - Services 172, 206
North
Johore Bahru Terminal - Service 170

Woodlands Interchange - Services 169, 178, 181, 204, 208, 372

Admiralty Road (Marsiling) Terminal - Services 180, 182

Admiralty Road West Terminal - Services 160, 167

Sembawang Road End Terminal - Services 161, 164

Yishun Ave 5 Terminal - Services 800, 801

Yishun Central Terminal - Services 850, 851

Sembawang Terminal - Service 171

Jalan Kayu Terminal - Services 70, 103, 163, 214E, 214W

Ang Mo Kio Depot Terminal - Service 263

Ang Mo Kio Interchange - Services 24, 25, 74, 77, 130, 132, 132A, 133, 134, 136, 138, 159, 162, 165, 166, 168, 169, 261, 262, 265, 266, 267, 269

Serangoon Garden Terminal - Services 72, 100, 101, 104, 106, 107, 217, 315

Upper Thomson Terminal - Service 71
Hope this can be a reference to those who's interested.
Cheers and warm regards