serial port output from 8051 micro is incomplete and reversed - serial-port

Question

I'm trying to make a program in the 8051 machine language that allows me to send data from its ROM to the PC in 16-byte chunks asynchronously so that it can do other work at the same time. In this code, I was expecting the following output on my screen:
Central station Debug Mode
Testing 115200bps speed mode with 16 byte chunks
12345678901234567890123456789012345678901234567890123456789012345678901234567890
80x25 screen?
uC to Linux screen test
Working? Yes? Maybe? No?
Test 100% wireless. 115200bps speed
TEST IS NOW FINISHED!
TX TEST OVER WAITING FOR RECEPTION!
However, I received much less than that. The output I actually received (according to the screen command in Linux) is the following:
OITPECER ROF
!H
I look at that text and it makes me think it processed the last 16 bytes whilst skipping one along with the rest of the beginning bytes.
I got both the microcontroller and the PC that I'm testing with both set to 115200 bps in raw mode with 8 data bits, no parity and 1 stop bit, and the power to both devices remained connected during the tests so I can't blame lack of power.
Is there anything I can do to this code to improve it so all text can be outputted correctly?
TXBUFS equ 30h
RXBUFS equ 40h
TXOP bit 7Dh
RXOP bit 7Ch
org 0h
ljmp main
org 23h ;serial INT
push PSW
setb RS0 ;all serial functions use bank 1.
jbc RI,rxdf
jbc TI,txdf
exitint:
clr RS0
pop PSW
reti
main:
mov SP,#52h
lcall serialinit
ljmp startdebug
;Serial port receive function
;Receiver controls R1 value unless we want to reset local buffer
rxdf:
cjne R1,#RXBUFS+17,noerx
clr RXOP
ajmp exitint
noerx:
mov #R1,SBUF
inc R1
ajmp exitint
;Serial port transmit function
txdf:
cjne R0,#TXBUFS+17,noetx
clr TXOP
ajmp exitint
noetx:
mov SBUF,#R0
inc R0
ajmp exitint
;enable receive
startrx:
setb RS0
mov R1,#RXBUFS
setb RXOP
clr RS0
ret
;Reset receiver stack
resetget:
setb RS0
mov R0,#RXBUFS+17
clr RS0
ret
;Get byte as A from receiver stack.
getrx:
setb RS0
dec R0
mov A,#R0
clr RS0
ret
;Reset our stack pointer (to zero bytes on transmitter stack)
resetadd:
setb RS0
mov R0,#TXBUFS+17
clr RS0
ret
;Add byte from A onto our transmitter stack. C=1 if end of stack reached
addtx:
setb RS0
dec R0
mov #R0,A
cjne R0,#TXBUFS,notxendp
setb C
inc R0
clr RS0
ret
notxendp:
clr C
clr RS0
ret
;send data
starttx:
setb TXOP ;set transmit busy flag
setb RS0
mov SBUF,#R0 ;send 1st byte right away to trigger interrupt later
inc R0
clr RS0
ret
;serial init
serialinit:
mov TH1,#0FFh ;speed=115kbps
mov TL1,TH1
mov PCON,#80h
mov SCON,#50h
mov TMOD,#22h ;auto reload for timers
setb RS0
mov R0,#TXBUFS+17 ;setup our pointers.
mov R1,#RXBUFS
clr RS0
setb TR1
setb ES
setb EA ;enable interrupts
ret
startdebug:
mov DPTR,#mmenu ;load text
lcall dprint ;and print it (not working correctly)
sjmp $
;print what's in ROM
dprint:
lcall resetadd ;reset transmitter pointer
dprint2:
clr A
movc A,#A+DPTR
inc DPTR
jz dexitp ;exit function if character from local ROM is 0h
lcall addtx ;send byte to transmitter
jnc nostall
;at this point, we made buffer full so do 16-byte transmission
lcall starttx
;and stall until all 16 bytes are transmitted
txst:
nop
jb TXOP,txst
;reset transmitter pointer again for next 16 bytes
lcall resetadd
nostall:
sjmp dprint2
dexitp:
;do one more round of transmission for remaining characters in transmit buffer
lcall starttx
;and stall again
txst2:
nop
jb TXOP,txst2
;and reset
lcall resetadd
ret
mmenu:
db 'Central station Debug Mode',0Dh,0Ah,0Dh,0Ah
db 'Testing 115200bps speed mode with 16 byte chunks',0Dh,0Ah
db '12345678901234567890123456789012345678901234567890123456789012345678901234567890',0Dh,0Ah
db '80x25 screen?',0Dh,0Ah
db 'uC to Linux screen test',0Dh,0Ah
db 'Working? Yes? Maybe? No?',0Dh,0Ah
db 'Test 100% wireless. 115200bps speed',0Dh,0Ah,0Dh,0Ah
db 'TEST IS NOW FINISHED!',0Dh,0Ah
db 'TX TEST OVER WAITING FOR RECEPTION!',0Dh,0Ah,00h