This screen mode is not suitable for displaying the desktop

Entry and EXIT are macros used for … etc.

Many thanks for that. Almost there.

It now runs with no errors (see below) but just gives the result Width=0 height=0. Still puzzled but will look more carefully tonight.

   10REM >TestVC3
   20REM Process is:
   30REM VCHIQ_Connect – “connect” your client to the GPU firmware
   40REM VCHIQ_ServiceOpen – open the “DISP” display service (&44495350)
   50REM VCHIQ_MsgQueue – send the EDispmanDisplayGetInfo message (14)
   60REM VCHIQ_MsgDequeue – read the response
   70REM VCHIQ_ServiceClose – close the display service
   80REM VCHIQ_Disconnect – “disconnect” from the GPU and deregister with VCHIQ
   90:
  100PROCinit
  110CALL looksee%
  120PRINT"Width=";!HWPDisplayWidth;" height=";!HWPDisplayHeight
  130END
  140:
  150DEFPROCinit
  160DIM prog% 30000
  170REM Data structure
  180REM Offset from start
  190VCHIQ_Service_Version=0
  200VCHIQ_Service_Version_Min=4
  210VCHIQ_Service_Id=8
  220VCHIQ_Service_Reserved=12
  230VCHIQ_Service_RxFifoSize=16
  240VCHIQ_Service_TxFifoSize=20
  250VCHIQ_Service_Callback=24
  260VCHIQ_Service_CallbackParam=28
  270VCHIQ_Service_WantUnalignedBulkRx=32
  280VCHIQ_Service_WantUnalignedBulkTx=36
  290VCHIQ_Service_WantCRC=40
  300VCHIQ_Service_Size=44
  310REM Constants
  320EDispmanDisplayOpen=8
  330EDispmanDisplayGetInfo=14
  340REMEDispmanResourceCreate=0
  350EDispmanDisplayClose=15
  360VCHI_CALLBACK_MSG_AVAILABLE=1
  370NoReply=(1<<31)
  380VCHI_FLAGS_BLOCK_UNTIL_QUEUED=04
  390I32_bit=0
  400FOR pass%=0 TO 3 STEP 3
  410P%=prog%
  420[OPT pass%
  430 ;Temp storage
  440 ALIGN
  450.VCHIQServiceN EQUD 0
  460.VCHIQServiceC EQUD 0
  470.VCHIQInstance EQUD 0
  480.HWPDispHandle EQUD 0
  490.VCHIQResponded EQUD 0
  500.HWPDisplayWidth EQUD 0
  510.HWPDisplayHeight EQUD 0
  520.HWPDisplayTrans EQUD 0
  530.HWPDisplayFormat EQUD 0
  540.RTDead EQUD 0
  550.RTActive EQUD 0
  560.mbxres EQUD 0
  570.disp% EQUD &44495350 ;'DISP'
  580.upd% EQUD &55504448 ; 'UPDH'
  590; Programme
  600.looksee%
  610        STMFD   sp!,{r0-r7,r14}
  620        SUB     sp,sp,#VCHIQ_Service_Size
  630        MOV     r0, r12
  640        SWI     "XVCHIQ_Initialise"
  650        MOVVS   r7, r0
  660        BVS     FT90
  670        STR     r0, VCHIQInstance
  680        MOV     r2, r0
  690        MOV     r1, #0
  700        MOV     r0, #0
  710        SWI     "XVCHIQ_Connect"
  720        MOVVS   r7, r0
  730        BVS     FT89
  740        ; Create services
  750        MOV     r0, #1
  760        STR     r0, [sp, #VCHIQ_Service_Version]
  770        STR     r0, [sp, #VCHIQ_Service_Version_Min]
  780        LDR     r0, disp%
  790        STR     r0, [sp, #VCHIQ_Service_Id]
  800        MOV     r0, #0
  810        STR     r0, [sp, #VCHIQ_Service_Reserved]
  820        STR     r0, [sp, #VCHIQ_Service_RxFifoSize]
  830        STR     r0, [sp, #VCHIQ_Service_TxFifoSize]
  840        ADR     r1, HWP_ClientCallback
  850        STR     r1, [sp, #VCHIQ_Service_Callback]
  860        STR     r0, [sp, #VCHIQ_Service_CallbackParam]
  870        STR     r0, [sp, #VCHIQ_Service_WantUnalignedBulkRx]
  880        STR     r0, [sp, #VCHIQ_Service_WantUnalignedBulkTx]
  890        STR     r0, [sp, #VCHIQ_Service_WantCRC]
  900        LDR     r0, VCHIQInstance
  910        MOV     r1, sp
  920        SWI     "XVCHIQ_ServiceOpen"
  930        MOVVS   r7, r0
  940        BVS     FT89
  950        STR     r0, VCHIQServiceC
  960      ;  LDR     r0, upd%
  970      ;  STR     r0, [sp, #VCHIQ_Service_Id]
  980      ;  ADR     r0, HWP_NotifyCallback
  990      ;  STR     r0, [sp, #VCHIQ_Service_Callback]
 1000      ;  LDR     r0, VCHIQInstance
 1010      ;  SWI     "XVCHIQ_ServiceOpen"
 1020      ;  MOVVS   r7, r0
 1030      ;  BVS     FT88
 1040      ;  STR     r0, VCHIQServiceN
 1050        ; Release services (message functions will 'use' them again)
 1060      ;  SWI     "XVCHIQ_ServiceRelease"
 1070        LDR     r0, VCHIQServiceC
 1080        SWI     "XVCHIQ_ServiceRelease"
 1090        ; Open display
 1100        MOV     r0, #EDispmanDisplayOpen
 1110        MOV     r1, #0
 1120        STMIA   sp, {r0-r1}
 1130        MOV     r0, #8
 1140        BL      HWP_Send
 1150        MOVVS   r7, r0
 1160        BVS     FT87
 1170        STR     r0, HWPDispHandle
 1180        ; Read width/height
 1190        MOV     r0, #EDispmanDisplayGetInfo
 1200        LDR     r1, HWPDispHandle
 1210        STMIA   sp, {r0-r1}
 1220        MOV     r0, #8
 1230        BL      HWP_Send
 1240        MOVVS   r7, r0
 1250        BVS     FT86
 1260;Read response (?)
 1270        CMP     R0,#0     ;CLRV
 1280        ADD     sp,sp,#VCHIQ_Service_Size
 1290        LDMFD   sp!,{r0-r7,r14}
 1300        MOV     PC,R14         ;EXIT
 1310.FT86
 1320        MOV     r0, #EDispmanDisplayClose + NoReply
 1330        LDR     r1, HWPDispHandle
 1340        STMIA   sp, {r0-r1}
 1350        MOV     r0, #8
 1360        BL      HWP_Send
 1370.FT87
 1380        LDR     r0, VCHIQServiceN
 1390        SWI     "XVCHIQ_ServiceUse"
 1400        LDR     r0, VCHIQServiceN
 1410        SWI     "XVCHIQ_ServiceClose"
 1420.FT88
 1430        LDR     r0, VCHIQServiceC
 1440        SWI     "XVCHIQ_ServiceUse"
 1450        LDR     r0, VCHIQServiceC
 1460        SWI     "XVCHIQ_ServiceClose"
 1470.FT89
 1480        LDR     r0, VCHIQInstance
 1490        SWI     "XVCHIQ_Disconnect"
 1500        MOV     r0, #0
 1510        STR     r0, VCHIQInstance
 1520       ; STR     r0, VCHIQServiceC
 1530        STR     r0, VCHIQServiceN
 1540.FT90
 1550        STR     r7, [sp]
 1560        CMP     R0, #1<<31 ;SetV
 1570        CMNVC   R0, #1<<31 ;SetV
 1580        ADD     sp,sp,#VCHIQ_Service_Size
 1590        LDMFD   sp!,{r0-r7,r14}
 1600        MOV     PC,R14 ;EXIT
 1610.HWP_ClientCallback
 1620        ; Did we receive a message?
 1630        CMP     r1, #VCHI_CALLBACK_MSG_AVAILABLE
 1640        STREQ   r1, VCHIQResponded
 1650        MOV     pc, lr
 1660;.HWP_NotifyCallback
 1670;.HWP_CalcDisplayScaleOffset
 1680;.HWPResource
 1690;.HWPActive
 1700;.HWPPalDirty
 1710        ; Not needed
 1720        MOV     pc, lr
 1730.HWP_Send
 1740        ;ROUT
 1750        ;Entry   "r1-r3"
 1760        MOV     r2, r0
 1770        LDR     r0, VCHIQServiceC
 1780        SWI     "XVCHIQ_ServiceUse"
 1790        ADDVS     sp,sp,#VCHIQ_Service_Size
 1800        LDMVSFD   sp!,{r0-r7,r14}
 1810        MOVVS     PC,R14 ;EXIT    VS
 1820        MOV     r0, #0
 1830        STR     r0, VCHIQResponded
 1840        LDR     r0, VCHIQServiceC
 1850        ADD     r1, sp, #16
 1860        MOV     r3, #VCHI_FLAGS_BLOCK_UNTIL_QUEUED
 1870        SWI     "XVCHIQ_MsgQueue"
 1880        BVS     FT80
 1890        ; Response necessary?
 1900        LDR     r2, [r1]
 1910        TST     r2, #NoReply
 1920        BNE     FT91
 1930        ; Wait for response
 1940.FT10
 1950        ADR     r1, VCHIQResponded
 1960        BL      HWP_WaitFor
 1970        LDR     r0, VCHIQServiceC
 1980        ; Read response (into R1, i.e. VCHIQResponded)
 1990        ; Ordinarily response is 4 bytes, except for DisplayGetInfo
 2000        ; WS vars arranged so that we can use same buffer address
 2010        ;ASSERT  HWPDisplayWidth = VCHIQResponded+4
 2020        ;ASSERT  HWPDisplayHeight = VCHIQResponded+8
 2030        ;ASSERT  HWPDisplayTrans = VCHIQResponded+12
 2040        ;ASSERT  HWPDisplayFormat = VCHIQResponded+16
 2050        TEQ     r2, #EDispmanDisplayGetInfo
 2060        MOVNE   r2, #4
 2070        MOVEQ   r2, #20
 2080        MOV     r3, #0
 2090        SWI     "XVCHIQ_MsgDequeue"
 2100        BVS     FT80
 2110        LDR     r0, VCHIQServiceC
 2120        SWI     "XVCHIQ_ServiceUse"
 2130        LDR     r0, [r1]
 2140        CMP     R0,#0 ;CLRV
 2150        ADD     sp,sp,#VCHIQ_Service_Size
 2160        LDMFD   sp!,{r0-r7,r14}
 2170        MOV     PC,R14 ;EXIT
 2180.FT80
 2190        MOV     r1, r0
 2200        LDR     r0, VCHIQServiceC
 2210        SWI     "XVCHIQ_ServiceUse"
 2220        MOV     r0, r1
 2230        CMP     R0, #1<<31 ;SetV
 2240        CMNVC   R0, #1<<31 ;SetV
 2250        ADD     sp,sp,#VCHIQ_Service_Size
 2260        LDMFD   sp!,{r0-r7,r14}
 2270        MOV     PC,R14 ;EXIT
 2280.FT91
 2290        LDR     r0, VCHIQServiceC
 2300        SWI     "XVCHIQ_ServiceUse"
 2310        CMP     R0,#0 ;CLRV
 2320        ADD     sp,sp,#VCHIQ_Service_Size
 2330        LDMFD   sp!,{r0-r7,r14}
 2340        MOV     PC,R14 ;EXIT
 2350.HWP_WaitFor
 2360        ; Wait for pollword at r1 to become nonzero
 2370        ; Assumes interrupts can be enabled!
 2380        STMFD   r13!,{r14}
 2390.FT71
 2400        LDR     r0,[r1]
 2420        CMP     r0,#0
 2430        BEQ     FT71
 2431        LDMFD   r13!,{r14}
 2440        MOV     PC,R14
 2650 ]
 2660NEXT pass%
 2670ENDPROC
>RUN
0000AE6C                    OPT pass%
0000AE6C                    ;Temp storage
0000AE6C                    ALIGN
0000AE6C 00000000 .VCHIQServiceN EQUD 0
0000AE70 00000000 .VCHIQServiceC EQUD 0
0000AE74 00000000 .VCHIQInstance EQUD 0
0000AE78 00000000 .HWPDispHandle EQUD 0
0000AE7C 00000000 .VCHIQResponded EQUD 0
0000AE80 00000000 .HWPDisplayWidth EQUD 0
0000AE84 00000000 .HWPDisplayHeight EQUD 0
0000AE88 00000000 .HWPDisplayTrans EQUD 0
0000AE8C 00000000 .HWPDisplayFormat EQUD 0
0000AE90 00000000 .RTDead   EQUD 0
0000AE94 00000000 .RTActive EQUD 0
0000AE98 00000000 .mbxres   EQUD 0
0000AE9C 44495350 .disp%    EQUD &44495350 ;'DISP'
0000AEA0 55504448 .upd%     EQUD &55504448 ; 'UPDH'
0000AEA4                    ; Programme
0000AEA4          .looksee% 
0000AEA4 E92D40FF           STMFD   sp!,{r0-r7,r14}
0000AEA8 E24DD02C           SUB     sp,sp,#VCHIQ_Service_Size
0000AEAC E1A0000C           MOV     r0, r12
0000AEB0 EF079200           SWI     "XVCHIQ_Initialise"
0000AEB4 61A07000           MOVVS   r7, r0
0000AEB8 6A000042           BVS     FT90
0000AEBC E50F0050           STR     r0, VCHIQInstance
0000AEC0 E1A02000           MOV     r2, r0
0000AEC4 E3A01000           MOV     r1, #0
0000AEC8 E3A00000           MOV     r0, #0
0000AECC EF079201           SWI     "XVCHIQ_Connect"
0000AED0 61A07000           MOVVS   r7, r0
0000AED4 6A000036           BVS     FT89
0000AED8                    ; Create services
0000AED8 E3A00001           MOV     r0, #1
0000AEDC E58D0000           STR     r0, [sp, #VCHIQ_Service_Version]
0000AEE0 E58D0004           STR     r0, [sp, #VCHIQ_Service_Version_Min]
0000AEE4 E51F0050           LDR     r0, disp%
0000AEE8 E58D0008           STR     r0, [sp, #VCHIQ_Service_Id]
0000AEEC E3A00000           MOV     r0, #0
0000AEF0 E58D000C           STR     r0, [sp, #VCHIQ_Service_Reserved]
0000AEF4 E58D0010           STR     r0, [sp, #VCHIQ_Service_RxFifoSize]
0000AEF8 E58D0014           STR     r0, [sp, #VCHIQ_Service_TxFifoSize]
0000AEFC E28F10DC           ADR     r1, HWP_ClientCallback
0000AF00 E58D1018           STR     r1, [sp, #VCHIQ_Service_Callback]
0000AF04 E58D001C           STR     r0, [sp, #VCHIQ_Service_CallbackParam]
0000AF08 E58D0020           STR     r0, [sp, #VCHIQ_Service_WantUnalignedBulkRx]
0000AF0C E58D0024           STR     r0, [sp, #VCHIQ_Service_WantUnalignedBulkTx]
0000AF10 E58D0028           STR     r0, [sp, #VCHIQ_Service_WantCRC]
0000AF14 E51F00A8           LDR     r0, VCHIQInstance
0000AF18 E1A0100D           MOV     r1, sp
0000AF1C EF07920A           SWI     "XVCHIQ_ServiceOpen"
0000AF20 61A07000           MOVVS   r7, r0
0000AF24 6A000022           BVS     FT89
0000AF28 E50F00C0           STR     r0, VCHIQServiceC
0000AF2C                    ;  LDR     r0, upd%
0000AF2C                    ;  STR     r0, [sp, #VCHIQ_Service_Id]
0000AF2C                    ;  ADR     r0, HWP_NotifyCallback
0000AF2C                    ;  STR     r0, [sp, #VCHIQ_Service_Callback]
0000AF2C                    ;  LDR     r0, VCHIQInstance
0000AF2C                    ;  SWI     "XVCHIQ_ServiceOpen"
0000AF2C                    ;  MOVVS   r7, r0
0000AF2C                    ;  BVS     FT88
0000AF2C                    ;  STR     r0, VCHIQServiceN
0000AF2C                    ; Release services (message functions will 'use' them again)
0000AF2C                    ;  SWI     "XVCHIQ_ServiceRelease"
0000AF2C E51F00C4           LDR     r0, VCHIQServiceC
0000AF30 EF07920E           SWI     "XVCHIQ_ServiceRelease"
0000AF34                    ; Open display
0000AF34 E3A00008           MOV     r0, #EDispmanDisplayOpen
0000AF38 E3A01000           MOV     r1, #0
0000AF3C E88D0003           STMIA   sp, {r0-r1}
0000AF40 E3A00008           MOV     r0, #8
0000AF44 EB000029           BL      HWP_Send
0000AF48 61A07000           MOVVS   r7, r0
0000AF4C 6A000010           BVS     FT87
0000AF50 E50F00E0           STR     r0, HWPDispHandle
0000AF54                    ; Read width/height
0000AF54 E3A0000E           MOV     r0, #EDispmanDisplayGetInfo
0000AF58 E51F10E8           LDR     r1, HWPDispHandle
0000AF5C E88D0003           STMIA   sp, {r0-r1}
0000AF60 E3A00008           MOV     r0, #8
0000AF64 EB000021           BL      HWP_Send
0000AF68 61A07000           MOVVS   r7, r0
0000AF6C 6A000003           BVS     FT86
0000AF70                    ;Read response (?)
0000AF70 E3500000           CMP     R0,#0     ;CLRV
0000AF74 E28DD02C           ADD     sp,sp,#VCHIQ_Service_Size
0000AF78 E8BD40FF           LDMFD   sp!,{r0-r7,r14}
0000AF7C E1A0F00E           MOV     PC,R14         ;EXIT
0000AF80          .FT86     
0000AF80 E3A0013E           MOV     r0, #EDispmanDisplayClose + NoReply
0000AF84 E51F1114           LDR     r1, HWPDispHandle
0000AF88 E88D0003           STMIA   sp, {r0-r1}
0000AF8C E3A00008           MOV     r0, #8
0000AF90 EB000016           BL      HWP_Send
0000AF94          .FT87     
0000AF94 E51F0130           LDR     r0, VCHIQServiceN
0000AF98 EF07920D           SWI     "XVCHIQ_ServiceUse"
0000AF9C E51F0138           LDR     r0, VCHIQServiceN
0000AFA0 EF079209           SWI     "XVCHIQ_ServiceClose"
0000AFA4          .FT88     
0000AFA4 E51F013C           LDR     r0, VCHIQServiceC
0000AFA8 EF07920D           SWI     "XVCHIQ_ServiceUse"
0000AFAC E51F0144           LDR     r0, VCHIQServiceC
0000AFB0 EF079209           SWI     "XVCHIQ_ServiceClose"
0000AFB4          .FT89     
0000AFB4 E51F0148           LDR     r0, VCHIQInstance
0000AFB8 EF079202           SWI     "XVCHIQ_Disconnect"
0000AFBC E3A00000           MOV     r0, #0
0000AFC0 E50F0154           STR     r0, VCHIQInstance
0000AFC4                    ; STR     r0, VCHIQServiceC
0000AFC4 E50F0160           STR     r0, VCHIQServiceN
0000AFC8          .FT90     
0000AFC8 E58D7000           STR     r7, [sp]
0000AFCC E3500102           CMP     R0, #1<<31 ;SetV
0000AFD0 73700102           CMNVC   R0, #1<<31 ;SetV
0000AFD4 E28DD02C           ADD     sp,sp,#VCHIQ_Service_Size
0000AFD8 E8BD40FF           LDMFD   sp!,{r0-r7,r14}
0000AFDC E1A0F00E           MOV     PC,R14 ;EXIT
0000AFE0          .HWP_ClientCallback 
0000AFE0                    ; Did we receive a message?
0000AFE0 E3510001           CMP     r1, #VCHI_CALLBACK_MSG_AVAILABLE
0000AFE4 050F1170           STREQ   r1, VCHIQResponded
0000AFE8 E1A0F00E           MOV     pc, lr
0000AFEC                    ;.HWP_NotifyCallback
0000AFEC                    ;.HWP_CalcDisplayScaleOffset
0000AFEC                    ;.HWPResource
0000AFEC                    ;.HWPActive
0000AFEC                    ;.HWPPalDirty
0000AFEC                    ; Not needed
0000AFEC E1A0F00E           MOV     pc, lr
0000AFF0          .HWP_Send 
0000AFF0                    ;ROUT
0000AFF0                    ;Entry   "r1-r3"
0000AFF0 E1A02000           MOV     r2, r0
0000AFF4 E51F018C           LDR     r0, VCHIQServiceC
0000AFF8 EF07920D           SWI     "XVCHIQ_ServiceUse"
0000AFFC 628DD02C           ADDVS     sp,sp,#VCHIQ_Service_Size
0000B000 68BD40FF           LDMVSFD   sp!,{r0-r7,r14}
0000B004 61A0F00E           MOVVS     PC,R14 ;EXIT    VS
0000B008 E3A00000           MOV     r0, #0
0000B00C E50F0198           STR     r0, VCHIQResponded
0000B010 E51F01A8           LDR     r0, VCHIQServiceC
0000B014 E28D1010           ADD     r1, sp, #16
0000B018 E3A03004           MOV     r3, #VCHI_FLAGS_BLOCK_UNTIL_QUEUED
0000B01C EF079205           SWI     "XVCHIQ_MsgQueue"
0000B020 6A000012           BVS     FT80
0000B024                    ; Response necessary?
0000B024 E5912000           LDR     r2, [r1]
0000B028 E3120102           TST     r2, #NoReply
0000B02C 1A000018           BNE     FT91
0000B030                    ; Wait for response
0000B030          .FT10     
0000B030 E24F1F6F           ADR     r1, VCHIQResponded
0000B034 EB00001C           BL      HWP_WaitFor
0000B038 E51F01D0           LDR     r0, VCHIQServiceC
0000B03C                    ; Read response (into R1, i.e. VCHIQResponded)
0000B03C                    ; Ordinarily response is 4 bytes, except for DisplayGetInfo
0000B03C                    ; WS vars arranged so that we can use same buffer address
0000B03C                    ;ASSERT  HWPDisplayWidth = VCHIQResponded+4
0000B03C                    ;ASSERT  HWPDisplayHeight = VCHIQResponded+8
0000B03C                    ;ASSERT  HWPDisplayTrans = VCHIQResponded+12
0000B03C                    ;ASSERT  HWPDisplayFormat = VCHIQResponded+16
0000B03C E332000E           TEQ     r2, #EDispmanDisplayGetInfo
0000B040 13A02004           MOVNE   r2, #4
0000B044 03A02014           MOVEQ   r2, #20
0000B048 E3A03000           MOV     r3, #0
0000B04C EF079204           SWI     "XVCHIQ_MsgDequeue"
0000B050 6A000006           BVS     FT80
0000B054 E51F01EC           LDR     r0, VCHIQServiceC
0000B058 EF07920D           SWI     "XVCHIQ_ServiceUse"
0000B05C E5910000           LDR     r0, [r1]
0000B060 E3500000           CMP     R0,#0 ;CLRV
0000B064 E28DD02C           ADD     sp,sp,#VCHIQ_Service_Size
0000B068 E8BD40FF           LDMFD   sp!,{r0-r7,r14}
0000B06C E1A0F00E           MOV     PC,R14 ;EXIT
0000B070          .FT80     
0000B070 E1A01000           MOV     r1, r0
0000B074 E51F020C           LDR     r0, VCHIQServiceC
0000B078 EF07920D           SWI     "XVCHIQ_ServiceUse"
0000B07C E1A00001           MOV     r0, r1
0000B080 E3500102           CMP     R0, #1<<31 ;SetV
0000B084 73700102           CMNVC   R0, #1<<31 ;SetV
0000B088 E28DD02C           ADD     sp,sp,#VCHIQ_Service_Size
0000B08C E8BD40FF           LDMFD   sp!,{r0-r7,r14}
0000B090 E1A0F00E           MOV     PC,R14 ;EXIT
0000B094          .FT91     
0000B094 E51F022C           LDR     r0, VCHIQServiceC
0000B098 EF07920D           SWI     "XVCHIQ_ServiceUse"
0000B09C E3500000           CMP     R0,#0 ;CLRV
0000B0A0 E28DD02C           ADD     sp,sp,#VCHIQ_Service_Size
0000B0A4 E8BD40FF           LDMFD   sp!,{r0-r7,r14}
0000B0A8 E1A0F00E           MOV     PC,R14 ;EXIT
0000B0AC          .HWP_WaitFor 
0000B0AC                    ; Wait for pollword at r1 to become nonzero
0000B0AC                    ; Assumes interrupts can be enabled!
0000B0AC E92D4000           STMFD   r13!,{r14}
0000B0B0          .FT71     
0000B0B0 E5910000           LDR     r0,[r1]
0000B0B4 E3500000           CMP     r0,#0
0000B0B8 0AFFFFFC           BEQ     FT71
0000B0BC E8BD4000           LDMFD   r13!,{r14}
0000B0C0 E1A0F00E           MOV     PC,R14
Width=0 height=0
>

You’ve got some Entry/EXIT issues with HWP_Send – the Entry is missing and it’s using EXITs that corresponds to looksee.

You’ve got some Entry/EXIT issues with HWP_Send

Many, many thanks, so I had. It now responds with 1920 and 1080. Gosh!

ScrHelp utility updated to version 0.03. Still a few warts as BASIC sometimes crashes (I suspect I may be pushing my luck with stack space). Also only works on Pi (need some error traps to allow it ignore Pi-specific stuff for other platforms).

Here is a simple example where next is used in both subsections:

I have realised that was not a good example, because next is a back reference and will work without the special assembly. Try these two subsections with next as a forward reference:

DEFFNsub1
 [OPT pass%
 ADD     r0,r0,#5
 B       next
 ADD     r0,r0,#5
 .next
 ]
=0
DEFFNsub2
 [OPT pass%
 ADD     r0,r0,#3
 B       next
 ADD     r0,r0,#3
 .next
 ]
=0

actualy the monitor is native 1920×1200, though I am on a RPi2, so not pushing it that far

Is there a problem with 1920×1200 on any RPI model? BeagleBoard, certainly. PandaBoard, sometimes. But the RPi?

Not that I know of, though it is the absolute highest resulition supported by the RPi, and I never push a video controler to its upper limits.

If you configure hdmi_group=2, you can use hdmi_mode=77 which should get you 2560×1600.

Some have even succeeded with 4K video output, although that seems to limit refresh rate to 15-20Hz, which is not supported by most displays.

Program still does not work at reading the EDID on this one.

Assume you are using version 0.03?

Could you please run the following code and send me the result? I can then update the programme to work correctly (I only have a few monitors to test it on).

   10REM >Test
   20DIM buf% 3000
   30b%=0
   40a%=FNask(&30020,4,b%,136)
   50IF a% THEN
   60  REPEAT
   70    OSCLI("Save blk"+STR$(b%)+" "+STR$~(buf%)+" +88")
   80    b%+=1
   90    a%=FNask(&30020,4,b%,136)
  100  UNTIL (a%!0)<>0 OR b%>3
  110ELSE
  120  PRINT "No EDID data read - flag%=";flag%
  130ENDIF
  140END
  150:
  160DEFFNask(tag%,lrq%,req%,lrs%)
  170LOCAL ERROR
  180flag%=0
  190buf%!0=232  :REM Buffer size
  200buf%!4=0    :REM buffer request/response code
  210buf%!8=tag% :REM &40003 - Get physical display width height
  220buf%!12=lrs%:REM value buffer size
  230buf%!16=lrq%:REM value length
  240buf%!20=req%:REM send/rec value
  250buf%!24=0   :REM send/rec value
  260buf%!28=0:REM buffer end tag
  270ON ERROR LOCAL flag%=2
  280IF flag%=0 THEN SYS "XBCMSupport_SendTempPropertyBuffer",buf%,buf% TO ;flag%:IF (flag% AND 1)=0 THEN flag%=0
  290RESTORE ERROR
  300IF (flag% AND 1) OR flag%=2 THEN =0 ELSE =buf%+20

Ran that, can not send the result, as have no where to send it to.

send to fromdave (at) svrsig (dot) org – many thanks

STR$ now corrected in line 70 above.

The EDID data you sent contains the following information:
640×480 60Hz
800×600 56Hz
800×600 60Hz
1024×768 60Hz
1280×720 @ 60Hz
1920×540 @ 60Hz

Due to a bug, only the first of the first four is reported, i.e. 640×480 @ 60Hz – look out for version 0.05!

Due to the EDID data not following the spec the last two listed resolutions are not included where they should be (in bytes 38 to 53 of the block starting at buf%+28) where it specifies the x-resolution, y-resolution and frequency as up to 8 2-byte data sets. They are included as detailed timing information which takes a bit more decoding and as the spec just says it duplicates the easier to decode information I ignore it. Only the last three resolutions decoded are shown in the window.

Chris, for clarity can you confirm that your results above, were using data from DavidS’s native 1920×1200 monitor?

We did some test work on about 20 monitors some years ago for EDID on the a9home, about half the EDID files were wrong in one way or another. When EDID first came to RO5 we were told monitors are now nearly all correct…

Chris, for clarity can you confirm that your results above, were using data from DavidS’s native 1920×1200 monitor?

It is from his data. The ‘standard timing information – up to 8 2-byte fields’ is not used (set to 0101) in his data despite the spec requiring it and there are two detailed timing descriptors (1280 wide and 1920 wide) where the ‘vertical active lines’ are shown as &2D0 and &21C (i.e. 720 and 540) where the latter should clearly be &438 (i.e. 1080) or &4B0 (i.e. 1200).

Version 0.06 now reports what the EDID data say (including, at risk of duplication, info from the [first four] detailed timing descriptors, which are listed in decreasing preference order) – I can’t correct errors in the data!

Isn’t raspian correct for a native 1920×1200 monitor?

there are two detailed timing descriptors (1280 wide and 1920 wide) where the ‘vertical active lines’ are shown as &2D0 and &21C (i.e. 720 and 540) where the latter should clearly be &438 (i.e. 1080) or &4B0 (i.e. 1200).

540 * 2 = 1080. You’re almost certainly failing to decode the DTDs for interlaced modes correctly.

David: Can you try posting the mode file created by *CreateModeFile? ScreenModes’ EDID handling isn’t perfect, but it will be a lot more complete than Chris’s code.

it will be a lot more complete than Chris’s code.

Certainly will. I have read the EDID spec but only implemented part of it (as my utility is for information only). The EDID data are definitely wrong though in places for this particular monitor. I am decoding the DTDs as provided, the first of which (the preferred resolution) is given in bytes 54-71:

bytes 38-53: 01 01 (not used - up to eight 2-byte resolution/frequency data) 
bytes 54-71: 01 1D pixel clock/10kHz = 74250kHz
             00 72 51 - horiz &500 active &172 blanking
             D0 1E 20 - vertical &2D0 active &01E blanking
             6E 28 55 00 - horiz synch offset &6E pulse width &28
                           vert sync offset &5 pulse width &5
             80 68 21 - horiz display size &280 mm
                        vert display size &168 mm
             00 - horiz border pixels 
             00 - vert border lines
             1E - flags - not interlaced, no stereo, digital sep synch,
                          vert synch +ve, horiz synch +ve

This gives 1280 × 540 interlaced 60Hz Edit: I mean 1280 × 720 non-interlaced 60Hz – I transcribed the flags as 9E vice 1E.

I am not trying to decode the alternative SVD blocks for the available DTV formats as these data blocks are optional whereas the ones listed above are obligatory.

This gives 1280 × 540 interlaced

&2D0 = 720.

That looks like it should be a DTD for a standard 1280×720 @ 60Hz mode, except that the interlace flag is set, which would give it a (probably nonsense) resolution of 1280×1440.

&2D0 = 720.

Well spotted. The second (and final) DTD is:

bytes 72-89: 01 1D pixel clock/10kHz = 74250kHz
             80 18 71 - horiz &780 active &118 blanking
             1C 16 20 - vertical &21C active &016 blanking
             58 2C 25 00 - horiz synch offset &58 pulse width &2C
                           vert sync offset &2 pulse width &5
             80 68 21 - horiz display size &280 mm
                        vert display size &168 mm
             00 - horiz border pixels 
             00 - vert border lines
             9E - flags - interlaced, no stereo, digital sep synch,
                          vert synch +ve, horiz synch +ve

except that the interlace flag is set, which would give it a (probably nonsense) resolution of 1280×1440.

almost certainly failing to decode the DTDs for interlaced modes correctly

Version 0.08 should have sorted this out. Many thanks.

Is there a problem with 1920×1200 on any RPI model?

Not that I know of, though it is the absolute highest resulition supported by the RPi, and I never push a video controler to its upper limits.

I understand that the RPi (with recent RISCOS builds) can support 3840 × 2160 at 30 Hz – if anyone who’s actually doing that feels extremely generous I’d love to have an SD card image to give it a whirl. I’m afraid I find the idea of doing a RISCOS build myself too intimidating :-(

I understand that the RPi (with recent RISCOS builds) can support 3840 × 2160 at 30 Hz – if anyone who’s actually doing that feels extremely generous I’d love to have an SD card image to give it a whirl. I’m afraid I find the idea of doing a RISCOS build myself too intimidating :-(

You don’t need a special build of RISC OS. Just enter the correct information in config.txt We’ve had 2560×1440 running. There was an issue with the pointer disappearing at 2048 but that was fixed about a year ago.

There was an issue with the pointer disappearing at 2048 but that was fixed about a year ago.

I’m still running RISCOS 5.21 (08-Jul-13) – last time I looked, anything more recent than that was only available as a nightly build, not an image. Or have I missed something, or failed to understand something? Or was the fix something that could be applied without a rebuild of the OS?

I think most of us update our ROM often

Apparently – and I can see where to get the nightly build ROM image.

We also provide downloads for just the RISC OS ROM image itself, for those who are a little more adventurous in brewing their own SD card images.

Sadly, this doesn’t provide any information, nor a link to such information, about how one might go about doing this. I’m probably moderately adventurous, but I don’t have a clue where to begin.

Sadly, this doesn’t provide any information, nor a link to such information, about how one might go about doing this. I’m probably moderately adventurous, but I don’t have a clue where to begin.

Open the !Boot dir on the SD card you boot from. Does it contain a file called “Loader”? If so, this is the FAT partition the RPi boots from. Double-click on the Loader file (which is presented as a DOSFS image file), find the riscos/rom file. Replace it with a a new RISC OS ROM image, and you’re done.

Well, in theory. You might also need to update your !Boot sequence, and maybe the Raspberry Pi firmware files, because not all RISC OS versions are compatible with all RPi firmware versions. You can download the RPi firmware from here: https://github.com/raspberrypi/firmware/tree/master/boot

If there is no “Loader”, you have to put your (micro)SD card into a cardreader to access the FAT partition to replace the files.

After writing all that, I agree that we should have an easy-to-follow tutorial somewhere.

Many thanks. I’ll do a new SD card with the latest RC14 image first and hold onto my existing one (which I find does have Loader, however).

A few additional notes:

• On the Pi, “riscos/rom” is actually “riscos/img”; and I think that is what it should be for the SDCMOS module to work.

• Do not delete or overwrite your original ROM image. Prefix the filename with a “_” character. This is to give you the option or reverting, should you need to.
  Likewise, if you update your firmware files, make copies of the original ones.

• The SDCMOS module works by writing the CMOS RAM values directly into a special place at the start of the ROM image. Obviously if you change your ROM, shutting down the machine could cause current settings to be written into the new ROM. I tend to make use of this as a lazy man’s way of reconfiguring my machine, however it is inadvisable if the original and replacement ROMs have a large gap between as there is the risk that unplugged modules may go haywire due to module numbers changing and/or different CMOS locations having different meanings.
  Therefore, the last thing you should do before booting the new ROM is to quit all active applications, go to the command line and *Close and then count to five before pressing the reset button (or power cycling if you haven’t wired up the reset button). Do not shut down normally.

• The development ROMs start up slightly differently to the stable versions. You’ll see junk on-screen listing the invocation of each module in turn. This is normal.

• ROMs these days run in High Vector mode. This means page zero is…nothing. If you find stuff is crashy, install the ZeroPain module to fake page zero and log what is misbehaving. If it bugs you, or you have a lot of older/crashy software, asking nicely might get you a low vectors build of RISC OS.

Hmm. Perhaps I’m not adventurous enough. I think I’ll hang on for a new RC. It would be nice to drive my big monitor, but I can live with the 1600×1200 for the moment!

I don’t have a lot of older, crashy software – the only things I use are Draw, NetSurf, CreateSEC, ChangeFSI, FontEd, Paint, Zap, BBC BASIC, and stuff I wrote myself, mostly in BASIC with just a few chunks of assembler for heavy data manipulation – nothing that’s likely to upset anything.

Does RC14 (8-Jul-13) run in High Vector mode? It’s giving me no trouble – apart from not driving my big monitor!

Thanks, David. I suspected that, but wasn’t sure. Like I wrote, I think I’ll wait for a new RC before trying to drive the big monitor – what Steffen said looked manageable, but Rick has scared me off! It sounds like the kind of thing I’d take on if I had to, but not cheerfully!