My knowledge of 8080 assembly is totally weak, but here I go:
On Tue, 15 Apr 2003, Dwight K. Elvey wrote:
> BOOTSTRP.ASM
>
> ; 42 BYTE BOOTSTRAP LOADER WITH INIT FOR 8250
> ; INTENDED FOR THE H89 BUT MAY ASLO WORK ON H8.
>
>
> ORG 2300H
> LDR: XRA A
> OUT LCNTL ; LINE CONTROL
> OUT IER ; NO INTERRUPTS
> OUT MCNTL ; INIT MODEM CONTROL
> DCR A ; SHOULD BE 'MVI A, 80H' BUT 0FFH OK?
> OUT LCNTL
> MVI A, 0CH ; 9600 BAUD
> OUT DVL
> XRA A
> OUT DVH
Why not move this up so you don't have to repeat the XRA A? Or does this
have to be here?
> MVI A, 07H ; 8 BIT 2 STOPS
> OUT LCNTL
> IN LSTAT
> IN RX ; CLEAR ANY JUNK
> LXI H, 2400H ; DEPENDS ON SIZE (TO BE DETERMINED)
> LDR1: IN LSTAT
> ANI 01
> JZ LDR1 ; WAIT FOR CHAR
> IN RX
> MOV M,A
> DCX H
> JMP LDR ; ADDRESS TO BE OVER WRITTEN BY CODE LOADED
How does this work if the address is two bytes but the code is loaded one
byte at a time?
--
Sellam Ismail Vintage Computer Festival
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Received on Wed Apr 16 2003 - 10:37:00 BST