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(Topic ID: 222797)

NEW! Williams System 3-7 In-Game Test ROMs


By pincoder

2 years ago



Topic Stats

  • 241 posts
  • 34 Pinsiders participating
  • Latest reply 3 months ago by pincoder
  • Topic is favorited by 61 Pinsiders

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#24 2 years ago

Hey - just downloaded your images - I have a FLASH game that isn't booting I fail the first test - leds don't flash, so it's time to start removing ICs. Bummer! All the signals (looking with a scope) look good - the uP is running. Some of the databus lines look questionable so it could be the RAM or the PIA. Neither is in a socket... It would be nice if there was some alternate signal you could toggle besides the LEDs so I could isolate it between the PIA or the databus... Anyway - glad you are doing this - it's been hard to find the previous testroms (Andre/Leon) and their instructions on the web.

#25 2 years ago

looking at Mouser and Digikey - the mainstream EEPROM are now the 1Mb parts. the 28C256 parts are ~$6 while the 39SF010 (1Mb) is ~$1.37. However, the 1Mb part is a 32 pin dip. While $5 isn't much, it might be better to change the layout to support the 32pin footprint to future proof the design? The UV 27x256 parts are, however, all over ebay between $2 and $10 bucks, but since I don't have a UV eraser, I like the EE parts better... just a thought.

#27 2 years ago

Good point.- forgot to search for those.

#32 2 years ago

thanks - I got the NVRAM pulled off and still not running. I'll head back to the garage (I mean my lab!) and check those other signals. I don't have a programmer here (it's at the office), so I'll try that bus test tomorrow night.

#33 2 years ago

Here's the testing...

Quoted from pincoder:

1) Check that CA2 on PIA1 is high while this test is running. Without it IC2 will not do anything with the LEDs. Also check that pin 15 on IC2 is low enough to be a logic 0 and that SW2 is open.

on PIA1, on pins 1 - 20, only 1 and 18 are low and the rest are high (steady state). on the other side of the IC, all the pins are toggling - 21-24 are fast toggles (looks correct), 25 clock is ok, 26-33 looks like the databus, 34 high (reset), 35-36 looks like the address bus and 37/38 high and 39/40 low

Quoted from pincoder:

2) Are you seeing the toggles on PA4 and PA5?

no, but.... if I press SW 1 (diag) I can get the those pins (and therefor the LED) to turn on or off. The only change when I press the button (not all the time ~20% of the time) and usually they sequence top on, both on, both off... Since that is just toggling the NMI, is there something in the code executing ???

Quoted from pincoder:

3) What about VMA on IC1? You should be seeing toggles there as well as IC8 (14,13,3).

yes VMA looks good at the processor and the address buffers, chipselect logic etc

Quoted from pincoder:

4) Have you tried 02-blanking? It just toggles the PA2 to keep the blanking circuit happy and would give you another signal to test.

no difference, however, depressing SW1 doesn't change the LEDS (both on) - PA2 stays high

#35 2 years ago
Quoted from pincoder:

The NMI switch and IC2 circuits will light the LEDs at the same time all by the hardware, so what you're seeing is normal, and is not a function of software.......

I'll try test 12 next. The test0 looked as expected. One issue is that the system 4 board has a 6800 processor - not the 6802/6808, so your text file could be updated as the pinout of the 6800 is slightly different. (pin 3/7/34/35/36/37/38 have different functions) the 6800 doesn't have the internal RAM either - are the test roms using that RAM?

Here's a summary of the differences for anyone interested..

From a code standpoint the MC6800, MC6802 and MC6808 mpu’s are interchangeable.
MC6802 is a MC6800 with 128 bytes of RAM and an on-board oscillator.
MC6808 is a MC6800 with an on-board oscillator but no RAM.

#40 2 years ago
Quoted from zacaj:

From a code point of view, it shouldn't be any different. The internal RAM is mapped to the same address space. You can also jumper the board to use the external ram with a 6802

cool... I was just concerned as the test rom goal is to isolate components. If it was using internal RAM, but actually with the 6800 it was external ram, it would be unexpectedly accessing the external RAM.

5 months later
#85 1 year ago

Hey Pincoder.... I finally got a chance to continue working on my dead MPU board for Flash and finally (with the help of your ROMs) I found the issue. The 7410 that decodes the read/write for the data buffers had one input not working, so when doing a read, it was OK, but on the write, the data transceivers were not being enabled at the right time so I would always write 0's . Never been so happy as seeing the LED blink!!! It wasn't an obvious failure - the IC wasn't hot, and the input pin was toggling correctly. Anyway, that was the only issue keeping the game from booting - now to do fix the drop targets and rebuild the flippers and I'll be a happy camper!

it made it nice to run the RAM and Light tests w/o enabling everything else at first with the Game ROMs.

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