Studer firmware = week/year:

Studer A807:                      
    20/87                       
    48/87 (25.11.87)      
    30/88                      
    01/89                      
    10/89                      
    20/91                       
    20/92                                
                                            
Studer A810:                      
    13/83   initial       
    (40/85) There are no hardware modifications necessary — just replace the three EPROM's only.
    25/86   for MPU PCB 1.820.780.81 and 1.820.780.82 (Layout 1.820.780.12) - hardware modification necessary. Otherwise just replace the three EPROM's only.
    01/88   <-- preferred. Old boards (MPU PCB 1.810.752.00) with software 07/83 MPU-board needs to be exchanged. Order number for MPU PCB with software 01/88: 1.810.780.22. Otherwise just replace the three EPROM's only.
    46/90                       
    25/91                       
    CodeDly722: R0257

Studer A812:
    Capstan:    37/89
    TDC MKI:    14/90
    TDC MKII:   06/89
    MPU MKI:    14/90
    MPU MKII:   06/89, 15/97
    CodeDly722: R0257
    
Studer A816:
    Capstan:    10/92
    MPU TD:     28/94, 18/98
    MPU MSTR:   28/94, 18/98

Studer A820-2:
    Capstan:    35/88, 37/89, 10/92
    MPU TD:     38/88, 35/95
    MPU MSTR MKI:   38/86, 06/89
    MPU MSTR MKII:  06/89, 02/93
    CodeDly722: R0257

Studer A820-24:      
    Capstan:    35/88, 37/89, 10/92  
    MPU TD:     48/89, 16/91, 18/91, 50/92  
    MPU MSTR:   20/89, 04/91    
    MPU Audio:  20/89, 41/90, 42/90        
    MPU VU:     20/89, 42/90
    MPU VU Rem: 27/88, 42/90
  
Studer A827 (24):                                          
    Capstan:    10/92                                    
    MPU TD:     10/92, 50/92, 35/95
    MPU MSTR:   10/92, 50/92, 16/97
    MPU Audio:  10/92, 50/92
    MPU Rem:    48/89  

Studer A800-24:
    6800 MPU:
    R5100-9
    R5101-9
    R5102-9
    R5103-9
    
Studer Autoloc:
    R0155, R0156
    
Revox PR99:
    Ic9: 04/84