MCMs Final Hi-Res Astrocade - Report 2

[@ballyalley]

Hi-Res Report #2 - Comments This video really gave me a warm feeling. You manage to show that the Astrocade has the power to be more than it was when it shipped in 1978. Your hi-res upgrade quadruples its resolution. Plus, you show a diagnostic device called BalCheck that can help users track down hardware failures. Here are a few additional comments. - Once these two project boards were designed by you, how long did it take to wire-them-up so that each one worked perfectly? - Creating a low-res-only breadboard as a diagnostic tool to help isolate a future hardware failure, or maybe even to simulate an error, is a great idea. 2:35 - This low-res-only breadboard set looks like a scheme that Doctor Frankenstein may have had in his laboratory; I mean this as a compliment. Maybe you should add a Jacob's Ladder to your lab. This arcing "toy" might not be healthy for your Astrocade's delicate health, but it will look cool. - I forgot to switch the video resolution to 720p until quite a bit into viewing it. Once I did that, then the quality was much-improved. - The 6" fan used to circulate air across your Astrocade's motherboard and your prototype boards is a trick which I have used before when I have spent considerable time typing in a program or programming in BASIC. Just a little bit of circulating air keeps the Astrocade surprisingly cool, but I don't suppose that this is a surprise to anyone. - This hardware setup would have been the envy of the home computer club in the 1970s. I wonder what Steve Wozniak would think of this Hi-Res Astrocade project. Does he even know the Bally Arcade exists? He was a 6502 fan himself; maybe he thinks that the Z80 CPU is rubbish. - Watching BalCheck HR run on the TV while observing the 7-segment displays was a treat. Thanks for sharing this hardware diagnostic tool with us. - The Z80 Check Diagnostic Utility looks incredibly helpful. Astrocade power-up that give only a black screen when there is a hardware failure are incredibly common. This black screen can be traced back to many different hardware failures. Having the ability to easily check the function of the Z80 is probably a dramatic time saver. - The hi-res breadboard has 16K of screen RAM on it, right? - It was a good idea to simulate a RAM error to demonstrate the diagnostic capability of your BalCheckHR. The error report for the bad RAM is: 0 4 I 2 0 H E L P. This is clever. It's amusing that the Astrocade is, essentially, asking for HELP. Your breakdown of the error report displayed on the 7-segment display makes it clear how powerful this hardware diagnostic tool is for someone who is troubleshooting an Astrocade. It's clear that it can really speed up the diagnostic process. - With your "Remote ROM Program," you're able to disable the on-board ROM with, it seems, the flick of a switch. This is an idea that is worth its weight in gold, for it seems like the failure of the 8K on-board ROM happens from time to time. If that is the only failure of the motherboard, then this "Remote ROM" would be an easy way to figure out if that is the only failure of the Astrocade's hardware. - Your explanation of your entire hardware setup is thorough and meticulous. I was able to follow this hardware progress report with ease. - I would absolutely love to see this hardware setup in person. I enjoyed this video immensely. I hope this progress report will give some aspiring Astrocade hackers a reason to create some of the projects that are available on ballyalley.com.

[@mcmsastrocades9366]

MCMs REPLY TO ADAM'S COMMENTARY HOW LONG DID IT TAKE TO WIRE UP THOSE 2 PROJECT BOARDS SO EACH ONE WORKED PERFECTLY? Creating a schematic for use with the Astrocade, breadboarding the scheme, testing and if necessary, tweaking the scheme so it functions perfect, takes many, many hours to complete. The larger the scheme, the more time is required. Then, the scheme has to be wire wrapped on a permanent board requiring even more time. Patience and perseverance are usually necessary to complete a hardware add-on or upgrade project for the Astrocade. What I normally do to stay focused and motivated, is look ahead, seeing in my mind the end result of my efforts. USING A SMALL FAN TO KEEP HEATED MOTHERBOARD COMPONENTS COOL I haven't decided yet if my final hi-res Astrocade will have an internal forced air fan to keep the heat generating components on the motherboard cooler. My decision will be made when I see how wide the add-under rack set up will be. There is likely not going to be enough room to mount the fan to force air up through the Astrocade console bottom and over the motherboard top. I might have to add some kind of baffle to redirect the air through the bottom of the Astrocade console. Otherwise , I'll run the Astrocade with the console top off and my 6" fan placed behind the Astrocade to blow some air across the left side of the motherboard. MCM DESIGN's UPGRADED BALCHECKHR DIAGNOSTIC BOARD I upgraded the original BALCHECK 7-segment display decoder and its error display sequence. The original BALCHECK error display sequence could be hard to read at times. I know this because I did breadboard and run the original Balcheck scheme. The Bally Alley has the original Balcheck scheme and program code. The upgraded decoder also allows the hex numbers A b C d E F to be displayed. In the error code sequence, I added what looks like a capital I. It looks like this ][. I did this for 2 reasons. When ][ is displayed, it indicates the data error INFO byte is displayed next. The other reason was to distinguish the scenario when the error code and the info byte are the same number. For example 04 ][ 04 HE LP Without the capital I present, the error sequence can be confusing to read. In my example, without the capital I present you would only see 04 HE LP flashing. I made some other display changes. I did preserve most of the original Balcheck program. The additional changes that I made were to upgrade the original Balcheck so it would be a more useful diagnostic tool. THE BLACK SCREEN POWER ON I did some investigating and found out the custom address and data chips normally power on initializing the TV display as a black screen. A software program has to set up the four TV display parameters as desired. Unfortunately, the ROM BIOS power up routine utilizes the ROM User Program Interface (UPI) to call 2 onboard subroutines to set up the TV display. The UPI and onboard subs utilize a Z80 stack area in the screen RAM when executed. If there is a motherboard failure relating to the screen RAM, the UPI will fail to execute and the TV display will remain black. The motherboard custom chip TV display output ports may still function even if there is a failure in screen RAM or its interfacing. During a motherboard failure, using Z80 output instructions directly (not within a subroutine) to set up the TV display will INCREASE the chance of the TV display powering on with some kind of color or graphics, instead of a black screen. This is why I won't use a subroutine to initialize the TV display in several of my Astrocade diagnostic programs. Perhaps the creator of the ROM BIOS was not concerned about any black screen power on and was simply trying to save a few bytes by setting up the TV display utilizing the UPI to call the onboard subs labeled SETOUT+1 (Sub#22) and COLSET+1 (Sub#24). YOUR BREADBOARD 1 HAD 16KB OF SCREEN RAM RIGHT? The hi-res breadboard 1 actually had 4 banks of 32KB SRAM, but the 3 address lines A12, A13 and A14 were grounded providing the needed 4 banks of 4KB RAM for hi-res. MCM DESIGN's REMOTE ROM DIAGNOSTIC PROGRAM The Remote ROM diagnostic program is useful as long as the motherboard ROM is functioning enough so it can be disabled. If the motherboard ROM is so bad that it's creating an issue with the operation of the Z80 address or data bus, then the Remote ROM program will also not execute. End Of Reply MCMs Final Hi-Res Astrocade - Report 2 March 2022

[@ballyalley]

@@mcmsastrocades9366 Thanks for your in-depth answer to my feedback. Also, thanks for re-posting your feedback to the Astrocade discussion group.