TURMON and TURMONH bug

General discussions related to the Altair 8800 Clone

TURMON and TURMONH bug

Postby TronDD » November 3rd, 2019, 8:07 pm

Both TURMON and TURMONH Turnkey monitor ROMs have a typo/bug in them.

; THIS SUBROUTINE BUILDS 3/6 OCTAL DIGITS IN H&L
;
; SPECIAL RETURN PROVIDED BY A "SPACE", CARRY BIT SET.
; ONLY VALID OCTAL OR "SPACE" ACCEPTED. ALL OTHERS FLAGGED AND
; CONTROL RETURNS TO MONITOR.

...

FDB7 37 STC ; SET THE CARRY
FDB8 C8 RZ ; RETURN IF "SPACE"
FDB9 E6B8 ANI 0B8H ; TEST FOR VALID OCTAL

^^ This should be ANI 0F8H unless you wanted p-w to be interpreted as valid octal. :)

The TURMON PROM Manual has the program listing with the correct value.

.M000
000000 201 123
000001 272 pqr
000002 126 012
000003 254 3?
.M0
000000 123
000001 012
000002 012
?00003 254
.
TronDD
 
Posts: 16
Joined: November 20th, 2018, 8:51 pm

Re: TURMON and TURMONH bug

Postby AltairClone » November 3rd, 2019, 9:06 pm

Very interesting! The TURMON manuals I’ve found also have B8h (270 octal) in them. Send me a link to the manual you found with the corrected value.

Mike
AltairClone
Site Admin
 
Posts: 421
Joined: April 5th, 2013, 10:55 am

Re: TURMON and TURMONH bug

Postby TronDD » November 4th, 2019, 10:28 am

Nope, you're right. My brain mistranslated 270. It is B8H. So now the question is why?

Was it a typo in the manual or is that bit sometimes relevant in some way?
TronDD
 
Posts: 16
Joined: November 20th, 2018, 8:51 pm

Re: TURMON and TURMONH bug

Postby AltairClone » November 4th, 2019, 10:49 am

Either it's just a mistake that was never corrected, or MITS had some oddball in house terminal that sent 30h-37h or 70h-77h when octal digits were typed based on some shift key or something on the keyboard and they wanted it to work either way.

I think i have an original TURMON EPROM. I'll dump it soon and see if it has B8 or F8.

Mike
AltairClone
Site Admin
 
Posts: 421
Joined: April 5th, 2013, 10:55 am

Re: TURMON and TURMONH bug

Postby TronDD » November 6th, 2019, 9:57 am

I'm afraid it's going to end up being B8 and I'll remain confused. :D

There's a few cool tricks used in that code so I would guess they knew what they were doing.

Tim.
TronDD
 
Posts: 16
Joined: November 20th, 2018, 8:51 pm

Re: TURMON and TURMONH bug

Postby AltairClone » November 6th, 2019, 7:16 pm

The original TURMON PROMs I just examined also have B8h. Actually, MITS hardware and software designs were mediocre at best. Wouldn’t be surprised if it’s an oversight.

Mike
AltairClone
Site Admin
 
Posts: 421
Joined: April 5th, 2013, 10:55 am

Re: TURMON and TURMONH bug

Postby TronDD » November 6th, 2019, 7:26 pm

Huh... Thanks for looking. Very interesting.
TronDD
 
Posts: 16
Joined: November 20th, 2018, 8:51 pm


Return to General Discussions

Who is online

Users browsing this forum: No registered users and 1 guest