Quick Q*Bert Question

shilmover

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Say that 5 times fast! :)

Working on troubleshooting an issue with the character ROMs. am I correct in assuming that the character ROMs are stored in the FG chips, and the background in the BG?

I am debugging a multi game actually, but this should point me in the right direction.
 
Say that 5 times fast! :)

Working on troubleshooting an issue with the character ROMs. am I correct in assuming that the character ROMs are stored in the FG chips, and the background in the BG?

Yes, the moving characters sprites are in the FG chips and the tiled background graphics are in BG.

- James
 
Yes, the moving characters sprites are in the FG chips and the tiled background graphics are in BG.

- James

Thanks James...

That's what I figured.

Now I need to figure out why Q*Bert and FHMC Q*bert work, but Qubes is messed up on one of my Clay MultiQBerts. ROMs are okay as I can swap in known good.
 
Thanks James...

That's what I figured.

Now I need to figure out why Q*Bert and FHMC Q*bert work, but Qubes is messed up on one of my Clay MultiQBerts. ROMs are okay as I can swap in known good.

Qubes used an additional address line controlled by one of the output ports on the board to swap to the other half of the FG sprite ROMs. That's probably part of the ROM selection for the multi-game kit. Continuity test the control wiring from the FG board to the main plug-in.

- James
 
Qubes used an additional address line controlled by one of the output ports on the board to swap to the other half of the FG sprite ROMs. That's probably part of the ROM selection for the multi-game kit. Continuity test the control wiring from the FG board to the main plug-in.

- James

I did do that, and they are good. Will test it again better tonight.
 
Okay. Did some more testing...

There are 4 wires going from the main Multiboard (with the z80 on it) to the FG board. Continuity good on all.

Of the 4 wires (on the FG board):
- 1 connects to pin 26 (A13) of the 27c512 EPROM
- 2 connects to pin 27 (A14) of the 27c512 EPROM
- 3 connects to pin 1 (A15) of the 27c512 EPROM
- 4 connects to pin 2 of the 32-pin socket (not connected to the chips)

I am wondering if one of the chips on the main multiboard is bad.

I am going to put a probe to each of these pins and see what they do with a good board vs a bad one.

Edit:
I probed the board. Call them Board #1 (bad QBert Qubes characters) and Board #2. I get the following:

Board #1:
State Pin 1 Pin 26 Pin 27
No Game L L L
QBert L L H
FHMC QBert H L L
QBert Qubes L L L


Board #2:
State Pin 1 Pin 26 Pin 27
No Game L L L
QBert L L H
FHMC QBert H L L
QBert Qubes H L H

From the test, its obvious that the reason for the bad character ROMs on Board #1 is that the Banks are not being switched. So the question is, where is the problem?

The main Multiboard has the following chips on it:
- 74HCT373
- 74HCT245
- 74HCT373 (Board #2 has a 374 here)
- Main EPROM
- NVRAM
- z80
- one labeled: GAL22V10B 15LJ H424J45 (which I believe is the programmable "brain" behind the kit)

Any suggestions as to where the problem might be? I guess I could compare each of the boards at all pins, but that would be time consuming unless I can narrow it down.
 
Last edited:
Just so I'm clear... are there separate paging control lines going from the CPU plugin to the boards for the BG graphics and FG graphics, or is it a case of all the controls being shared by both BG & FG ?

- James
 
Just so I'm clear... are there separate paging control lines going from the CPU plugin to the boards for the BG graphics and FG graphics, or is it a case of all the controls being shared by both BG & FG ?

- James

I dont have the board in front of me (should have brought it to work), but as I recall, at least one control line is shared. I dont believe all of them are.

Edit: Slight clarification...

There are 4 lines going to the FG board & 3 going to the BG board. There are no wires connected directly between the FG & BG. They are traced through the main board.
 
Correction...

All 3 of the control lines are connected to both the FG & BG boards.
 
Adding the connections to the BG board (in blue):

Of the 4 wires (on the FG board):
- 1 connects to pin 26 (A13) of the 27c512 EPROM, no connection to BG board
- 2 connects to pin 27 (A14) of the 27c512 EPROM and to Pin 2 (A13) of the 27c128s (BG Board)
- 3 connects to pin 1 (A15) of the 27c512 EPROM and to Pin 26 (A13) of the 27c128s (BG Board)
- 4 connects to pin 2 of the 32-pin socket (not connected to the chips), connects to the 3 line on the BG board and to Pin 27 (PGM) on the 27c128s (BG Board)
 
Hi.

The 74HCT373 and the 74HCT374 are very different chips. The '373 is basically a latch and the '374 is a flip flop. Pin 11 on these chips is opposite polarity as well as a slightly different function. This is most likely the cause of the problem with board #1.

Kenneth
 
Hi.

The 74HCT373 and the 74HCT374 are very different chips. The '373 is basically a latch and the '374 is a flip flop. Pin 11 on these chips is opposite polarity as well as a slightly different function. This is most likely the cause of the problem with board #1.

Kenneth

Hmm. I need to check them again. The one I am trying to fix definitely has 2 74LS373s in it. Maybe I read the other one wrong. Anyone have one handy to look at? If not I will take a look tonight.

BTW, Pin 11 on both chips are connected (continuity between them)
 
I confirmed that the working one has a 74HC373 & a 374, but the non working one has 2x 373 chips.

Strange thing is that I got one of them from clay directly (not sure which).

Anyone have one that they can take a look at?
 
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