Difference between the two basic rom 11&19?

[e5frog]

I have 6540-019 in my PET 2001-8C, apparently there might be a -011 instead.
As far as I can determine they differ in 15 bytes, in this area:

-011 version:

.C:c584  A2 68       LDX #$68
.C:c586  86 65       STX $65
.C:c588  68          PLA
.C:c589  8D FD 01    STA $01FD
.C:c58c  68          PLA
.C:c58d  8D FE 01    STA $01FE
.C:c590  A2 FC       LDX #$FC
.C:c592  9A          TXS
.C:c593  A9 00       LDA #$00
.C:c595  85 8D       STA $8D
.C:c597  85 61       STA $61
.C:c599  60          RTS

-019 version:

.C:c584  A2 68       LDX #$68
.C:c586  86 65       STX $65
.C:c588  68          PLA
.C:c589  A8          TAY
.C:c58a  68          PLA
.C:c58b  A2 FE       LDX #$FE
.C:c58d  9A          TXS
.C:c58e  48          PHA
.C:c58f  98          TYA
.C:c590  48          PHA
.C:c591  A9 00       LDA #$00
.C:c593  85 8D       STA $8D
.C:c595  85 61       STA $61
.C:c597  60          RTS
.C:c598  51 60

Same here: http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/d/rom-1.html
Does anyone know what functionality has been changed? Is the second version doing the same thing just faster?

Should we call the one with -019 rom for version 1.1, it's called basic1r on zimmers.

 

[dave_m]

I think it was to fix a bug with the IEEE488 bus.
-Dave

 

[e5frog]

I have read the IEC-bus was fixed for V2, the one with # instead of * in the startup.

This:

.C:c589  8D FD 01    STA $01FD
.C:c58c  68          PLA
.C:c58d  8D FE 01    STA $01FE
.C:c590  A2 FC       LDX #$FC
.C:c592  9A          TXS

Was changed to:

.C:c589  A8          TAY
.C:c58a  68          PLA
.C:c58b  A2 FE       LDX #$FE
.C:c58d  9A          TXS
.C:c58e  48          PHA
.C:c58f  98          TYA
.C:c590  48          PHA

Is it in the IEC-bus area?
Quite nice if it was fixed already with the 011 to 019 ROM revision.