You could do your own buffering.
open create (unt,isz=1)"testfile"
chan=lfo
for i=1 to 100
rec$="test block "+str(i)+$04$
write record(chan)rec$
next i
close(chan)
open input(chan,isz=1)"testfile"
buf$=""
while 1
read record(chan,end=*break,bsy=*continue,tim=1,siz=-128)block$
buf$+=block$
x=pos($04$=buf$)
while x>0
rec$=buf$(1,x-1),buf$=buf$(x+1)
recs$+=rec$+$0a$ ! do whatever with the record
x=pos($04$=buf$)
wend
wend
close(chan)
print recs$