New test routine:

pub SPI_Test2|val2
  repeat 10
    ser.tx(13)
  repeat val from 0 to 255
    ser.tx("w")
    ser.hex(val,2)
    ser.tx(" ")
    ser.tx("r")
    ram.WriteByte(addr,val)
    val2 := ram.ReadByte(addr)
    ser.hex(val2,2)
    ser.tx(13)

Verifies my suspicion, writes are not writing correct value a lot of the time.

Best guess: CLK problem, either wrong edge, or ram can't handle 20Mbps writes.

w00 r00
w01 r01
w02 r02
w03 r03
w04 r05
w05 r07
w06 r06
w07 r07
w08 r09
w09 r0B
w0A r0C
w0B r0F
w0C r0D
w0D r0F
w0E r0E
w0F r0F
w10 r11
w11 r13
w12 r14
w13 r17
w14 r1B
w15 r1F
w16 r1C
w17 r1F
w18 r19
w19 r1B
w1A r1C
w1B r1F
w1C r1D
w1D r1F
w1E r1E
w1F r1F
w20 r21
w21 r23
w22 r24
w23 r27
w24 r2B
w25 r2F
w26 r2C
w27 r2F
w28 r33
w29 r37
w2A r38
w2B r3F
w2C r3B
w2D r3F
w2E r3C
w2F r3F
w30 r31
w31 r33
w32 r34
w33 r37
w34 r3B
w35 r3F
w36 r3C
w37 r3F
w38 r39
w39 r3B
w3A r3C
w3B r3F
w3C r3D
w3D r3F
w3E r3E
w3F r3F
w40 r41
w41 r43
w42 r45
w43 r47
w44 r4B
w45 r4F
w46 r4D
w47 r4F
w48 r53
w49 r57
w4A r5A
w4B r5F
w4C r5B
w4D r5F
w4E r5D
w4F r5F
w50 r63
w51 r67
w52 r6A
w53 r6F
w54 r77
w55 r7F
w56 r7A
w57 r7F
w58 r73
w59 r77
w5A r7A
w5B r7F
w5C r7B
w5D r7F
w5E r7D
w5F r7F
w60 r61
w61 r63
w62 r64
w63 r67
w64 r6B
w65 r6F
w66 r6C
w67 r6F
w68 r73
w69 r77
w6A r78
w6B r7F
w6C r7B
w6D r7F
w6E r7C
w6F r7F
w70 r71
w71 r73
w72 r74
w73 r77
w74 r7B
w75 r7F
w76 r7C
w77 r7F
w78 r79
w79 r7B
w7A r7C
w7B r7F
w7C r7D
w7D r7F
w7E r7E
w7F r7F
w80 r81
w81 r83
w82 r86
w83 r87
w84 r8B
w85 r8F
w86 r8E
w87 r8F
w88 r93
w89 r97
w8A r9C
w8B r9F
w8C r9B
w8D r9F
w8E r9E
w8F r9F
w90 rA3
w91 rA7
w92 rAC
w93 rAF
w94 rB7
w95 rBF
w96 rBC
w97 rBF
w98 rB3
w99 rB7
w9A rBC
w9B rBF
w9C rBB
w9D rBF
w9E rBE
w9F rBF
wA0 rC3
wA1 rC7
wA2 rCC
wA3 rCF
wA4 rD7
wA5 rDF
wA6 rDC
wA7 rDF
wA8 rE7
wA9 rEF
wAA rF9
wAB rFF
wAC rF7
wAD rFF
wAE rFC
wAF rFF
wB0 rE3
wB1 rE7
wB2 rEC
wB3 rEF
wB4 rF7
wB5 rFF
wB6 rFC
wB7 rFF
wB8 rF3
wB9 rF7
wBA rFC
wBB rFF
wBC rFB
wBD rFF
wBE rFE
wBF rFF
wC0 rC1
wC1 rC3
wC2 rC6
wC3 rC7
wC4 rCB
wC5 rCF
wC6 rCE
wC7 rCF
wC8 rD3
wC9 rD7
wCA rDC
wCB rDF
wCC rDB
wCD rDF
wCE rDE
wCF rDF
wD0 rE3
wD1 rE7
wD2 rEC
wD3 rEF
wD4 rF7
wD5 rFF
wD6 rFC
wD7 rFF
wD8 rF3
wD9 rF7
wDA rFC
wDB rFF
wDC rFB
wDD rFF
wDE rFE
wDF rFF
wE0 rE1
wE1 rE3
wE2 rE6
wE3 rE7
wE4 rEB
wE5 rEF
wE6 rEE
wE7 rEF
wE8 rF3
wE9 rF7
wEA rFC
wEB rFF
wEC rFB
wED rFF
wEE rFE
wEF rFF
wF0 rF1
wF1 rF3
wF2 rF6
wF3 rF7
wF4 rFB
wF5 rFF
wF6 rFE
wF7 rFF
wF8 rF9
wF9 rFB
wFA rFE
wFB rFF
wFC rFD
wFD rFF
wFE rFF
wFF rFF
 