VIC 1112 IEEE Interface

Vic 20 Item Exchange

Moderator: Moderators

Kakemoms
Vic 20 Nerd
Posts: 740
Joined: Sun Feb 15, 2015 8:45 am

Re: VIC 1112 IEEE Interface

Post by Kakemoms »

eslapion wrote: It's the opposite.

The MOS6522 IRQB can only drive low or do nothing at all. The 65C22 or R65C22 can drive low or high. This way you can connect more than one 6522 to the same IRQ line and this is done in many pieces of equipment. If a 6522 pulls low and a R65C22 pulls high then you have a tug of war between the two.

A diode may do the job but it has to be extremely fast and have a very low voltage drop. The 1N6263 I use on the Behr-Bonz DRL 'AND' gate should to the job.

A 10kOhms pull-up resistor will definitely not.
Thanks Eslapion. I didn't have that diode, but I managed to get it to work with a 1N5814:
IMG_5063.JPG
At least the R65C22 works for my Vic-20 and its keyboard. Unfortunately it didn't work for the IEEE device. I got the same problems as with the MOS 6522. E.g. "Load"$",9" loads the directory but displays nothing (unlike the original Vic-1112 which shows it):
IMG_5065.JPG
I will test more another day. Maybe there is a strange bug in the software or something about the R65C22 in this configuration.
Kakemoms
Vic 20 Nerd
Posts: 740
Joined: Sun Feb 15, 2015 8:45 am

Re: VIC 1112 IEEE Interface

Post by Kakemoms »

Short update: I moved the two MOS6522 from my Vic-20 into the IEEE interface and I get the same result. With two R65C22 in the Vic-20 (with the IRQ diode modification) I have keyboard and serial read/write (towards my Commodore 1541) working as before.

The program starts as usual (with SYS45065) and the EPROM verifies as being the same as the image you released. I will burn a new EPROM (with the original VIC-1112 image) and test if it works with that one.
dragos
Vic 20 Afficionado
Posts: 479
Joined: Mon Nov 21, 2005 6:41 pm

Re: VIC 1112 IEEE Interface

Post by dragos »

Please keep me informed of your progress. I suggest trying real mos 6522s, maybe you have a 1541 lying around you can borrow them from.

I test each board thoroughly prior to shipment (read/write and burn in) and this is the first issue not related to user soldering error I have had.

very curios to put the issue to bed and see you have a working card.

Thanks!
0110 0110 0110 The number of the beast...
User avatar
orion70
VICtalian
Posts: 4337
Joined: Thu Feb 02, 2006 4:45 am
Location: Piacenza, Italy
Occupation: Biologist

Re: VIC 1112 IEEE Interface

Post by orion70 »

Any news about the ETA for this interface? It's been a while since the Kickstarter campaign was closed...
Kakemoms
Vic 20 Nerd
Posts: 740
Joined: Sun Feb 15, 2015 8:45 am

Re: VIC 1112 IEEE Interface

Post by Kakemoms »

Just to follow up on this; I have just tested the cart with an original Vic-1112 ROM image. The SYS45065 starts the software, but I can not LOAD, format (PRINT#15,"NO:...) or SAVE to the disk. The original Vic-1112 cart works with this drive and can do all that, so there is something wrong with the cart.

I will try to re-flow the solder in case its just a poor connection. I am also a little unsure about some of the via holes as they do not seem to contain metal (or maybe they don't have the solder mask opened). It could of course also be one of the IC's, but I don't have any of these (except for the 74LS00N) here, so I can't check that easily.
Kakemoms
Vic 20 Nerd
Posts: 740
Joined: Sun Feb 15, 2015 8:45 am

Re: VIC 1112 IEEE Interface

Post by Kakemoms »

This has been long overdue, but I was able to test the MC3446N ICs that were used on my VIC1112 board using an IC tester that I built from these instructions. Quite cheap once you get the parts from ebay. If you decide to make one yourself, add this to the database for the 3446 test:

Code: Select all

$3446
16 
HH101HHGHH101HHV
HH100LLGHH101HHV
HH101HHGLL001HHV
LL000LLGLL001HHV
HH101HHGHH100LLV
HH100LLGHH100LLV
HH101HHGLL000LLV
LL000LLGLL000LLV
H1X1X1HGH1X1X1HV
H1X1X0LGH1X1X1HV
L0X1X1HGH1X1X1HV
L0X1X0LGH1X1X1HV
H1X1X1HGL0X1X0LV
H1X1X0LGL0X1X0LV
L0X1X1HGL0X1X0LV
L0X1X0LGL0X1X0LV

Anyway I found that two 3446s were dead and have ordered replacements. My 4040 is currently dead, so until I fix the drive I will not be able to test the VIC1112 with it, but I assume it will work. Anyway, the IC tester is nice to have around! I gave it some steroids with an MEGA 2560 board to get more pins (up to 32):
IMG_5831.JPG
Testing 3446 works.. if it works!
norm8332
Vic 20 Nerd
Posts: 626
Joined: Sun Nov 13, 2016 11:04 am
Location: USA

Re: VIC 1112 IEEE Interface

Post by norm8332 »

Thanks for the link for the tester, I have everything except the zif socket. Looks like a cool project.
“In religion and politics people’s beliefs and convictions are in almost every case gotten at second-hand, and without examination... whose opinions about them were not worth a brass farthing.”

-Autobiography of Mark Twain
Post Reply