New DOSBox user here, also using 43 and 50 line text displays. The text cursor disappears sometimes (hidden text cursor). I got the text cursor back by running a tiny program called EGA43.com which is described in this article,
https://books.google.com/books?id=hEaMhncO06E … a43.com&f=false
Googling turned up this site with a copy for download, http://www.minuszerodegrees.net/software/EGA43.COM
I've copied the assembly source that came along with my old DOS software below (the forum software wouldn't let me attach files) -- but I didn't assemble it myself -- the software also came with EGA43.com already assembled. Run it at the dos prompt to see if it fixes your cursor problem. I added a line to run it at the end of the [autoexec] section of the configuration file.
---------------
; EGA43.ASM Sets the IBM EGA screen to 43x80 characters
; from PC Tech Journal April 1985 page 77
; written by Thomas V.Hoffmann, January 1985
; Commented out portions to make it work on PS/2
; (still works on all old machines)
Bdata segment at 40H
org 63H
CRTC dw ?
org 87H
info db ?
Bdata ends
code segment public
org 100H
assume CS:code
main proc near
push ES
xor AX,AX
push AX
mov AX,Bdata
mov DS,AX
assume DS:Bdata
; mov AX,3 ; set 80-column mode using BIOS
; int 10H
mov AX,1112H ; load 8x8 font
mov BL,0 ; into block 0
int 10H ; and recalc screen
; or info,1 ; inhibit BIOS cursor emulation
mov AX,100H ; set the cursor
mov BH,0 ; for page 0
mov CX,000CH
; mov CX,0007H ; to a block
int 10H
mov DX,CRTC ; directly set underline to line 7
mov AL,14H
out DX,AL
inc DX
mov AL,7
out DX,AL
mov AX,1200H ; select EGA screen print
mov BL,20H
int 10H
; and info,0FEH ; enable BIOS cursor emulation
ret
main endp
code ends
end