[vcf-midatlantic] Mystery ROM from MITS 88-PMC ROM Board

[Herb Johnson]

 > It starts with LXI SP, 0xFF13 -- a ROM location. I've seen
 > the trick used elsewhere, to reduce code size by using
 > an in-ROM jump table. Anyone recognize the code?


ORG 0FF00H

LXI H, 0FF13H
LXI D, 2C00H
MVI C, 0EBH
L1: MOV A,M
STAX D
INX H
INX D
DCR C
JNZ L1	;0FF08H
JMP 2C00H

;above moves code from ROM to RAM and executes

ORG 2C00H; but code follows ROM code above at FF13H

DI
XRA A
OUT 22H
CMA
OUT 23H
MVI A, 2CH
OUT 22H
MVI A, 03H
OUT 19H
IN 0FFH
ANI 10H
RRC
RRC
ADI 10H
OUT 10H
LXI SP, 2D79H
XRA A

; next byte is at FF30H in ROM
; further disassembly should be instructive


-- 
Herbert R. Johnson,  New Jersey USA
http://www.retrotechnology.com OR .net