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Hi-Res Bally Arcade/Astrocade Correspondence


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  • 2 weeks later...
3 hours ago, Sonaru said:

It would be great to see what games can look like on a hi-res system that take advantage of it's capabilities. 

 

Yes, I too would love to see a high-res game written.  Of course, only Michael could play it.  I'm surprised more people haven't played around with hi-res by modifying games like Wizard of Wor or GORF.

 

Adam

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  • 2 weeks later...

Michael Matte has made his second hi-res update to the Astrocade discussion group.

 

----------------------------------------

 

From: Michael Matte
Sent: Wednesday, February 23, 2022 10:08 PM
To: ballyalley@groups.io
Subject: Re: [ballyalley] MCM Design Hi-Res News

 

Report 2 - MCM Design is pleased to announce that the wire wrapping (WW) for the screen static RAM (SRAM) prototype Board 1 is completed, with the exception of the 14 pin dual in-line ribbon cable (RC) connector, which is used to interconnect some control lines between Board 1 and Board 2.

 

Board 1 was tested for low and hi-res (no multi-pager) execution perfection using multiple tests, multiple times. Board 1 operates fantastic!

 

When the low-res scheme was wire wrapped, a hex inverter chip (74LS04) was found to be functioning, but "acting up". The chip was creating low-res graphic issues. This same chip was likely utilized on the breadboard 1, when hi-res graphic issues were occurring. MCM thought this chip was previously tested to be okay. However, when this chip, then on the WW Board 1, was replaced with a brand-new chip, the low-res graphic issues were no longer present. This surprising discovery ended a prolonged, frustrating, hit or miss bug search, delaying the Board 1 construction project several weeks. After this imperfect chip was replaced, MCM breezed through the remaining add-on wiring schemes.

 

The SRAM control lines interfacing is a slight variation taken from the Datamax UV-1R computer interfacing scheme. A 74LS123 chip is used so the active-low RAS line can be adjusted (shifted) for correct timing by manually turning a 5K ohm trimmer resistor.

 

The IC7 chip, which generates the 4 active-low CAS lines, actually used as the 4 hi-res SRAM bank chip selects (CS), was changed from type 74LS175 to the faster 74F175 series. This changed the low/hi-res mode operating range from a narrow trimmer adjustment range to the entire 5K ohm trimmer range. This was a pleasant and significant discovery. Once the operating range of the 5K ohm trimmer was known, the trimmer could then be eliminated and replaced with an appropriate sized, fixed resistor.

 

Two of the 4 chips that were relocated on Board 1 were mounted right next to the 28 pin ribbon cable connector. The two System and PX clocks from the Astrocade motherboard are wired to these 2 chips. Relocating these chips shortened the clock line lengths to around 5 1/2 inches. Whether or not this relocation improved the clock performance could not be determined. MCM Design does not have an oscilloscope to check for dirty or poor clock performance.

 

MCM went ahead and desoldered all the Astrocade motherboard components that are no longer necessary for low or hi-res operation. This includes the bypass (decoupling) capacitors, chips U21 and U22 and even the 9 vacant chip sockets. The Astrocade motherboard now has only 1 chip that is NOT installed in a PC socket. Nice! The 12VDC power supply was not removed at this time because MCM is not sure what kind of effect, if any, would be placed on the unusual power supply 8 diode rectification scheme.


What's next on MCM Design's projects agenda? The following lists MCM projects leading up to the final hi-res Astrocade Board 2 project.

 

Reassemble MCMs hi-res DRAM Astrocade.

 

The "modified for hi-res" motherboard on this Astrocade was connected to Board 1 to check for compatibility.

 

Wire wrap composite video driver and audio driver breadboard scheme.*
A quick connect replacement for the Aztec RF modulator.

 

Create new hi-res graphics demo called "Pixel Rectangles HR".

 

Record MCMs Astrocades YouTube video
title:MCMs Final Hi-Res Astrocade - Report 5
The WW Board 1 prototype is demonstrated in low and hi-res.
The quick-connect composite video and audio driver WW board replaces the Aztec RF modulator.
The new Hi-Res Demo is unveiled.

 

Revise/test 2 new diagnostic programs SCRwr and SCRwrHR (hi-res) for use with a logic analyzer.

 

Tear down multi-pager and user RAM/ROM schemes on the original SRAM WW prototype board.
Use components for the final hi-res Astrocade Board 2.

 

Revise (update) low/hi-res SRAM scheme on the original screen SRAM WW prototype board.
Use as a diagnostic tool/chip tester for the final hi-res Astrocade Board 1.

 

Wire wrap 4KB "low-res only" diagnostic breadboard scheme.*
This diagnostic tool can connect to the final hi-res Astrocade motherboard.

 

Wire wrap BalcheckHR breadboard scheme.*
Finally on a permanent board.

 

Build breadboard 2 for the final hi-res Astrocade.
Board 2 includes:
Eight 16KB multi-pager
User RAM and hi-res ROM
Hi-res ROM includes BIOS, separate extended graphics UPI subroutines and demos
Software low/hi-res select
14 pin RC interconnect to Board 1
50 pin expansion connect to the Astrocade motherboard
50 pin expansion connect to Board 3.


*Frees up breadboard strips for the final hi-res Astrocade (bread)Board 2 project.

 

End Of Report 2
FEB 2022

 

----------------------------------------

 

I'm SO glad to hear that Michael found his problem and things are looking up

 

Adam

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  • 2 weeks later...

Michael Matte has made his third hi-res update to the Astrocade discussion group.  He posted it here:

 

https://groups.io/g/ballyalley/message/19035

 

This is what he said in the post.

 

---------------------------------------

 

From: Michael Matte

Sent: Friday, March 25, 2022 1:16 AM

To: ballyalley@groups.io

Subject: Re: [ballyalley] MCM Design Hi-Res News

 

Report 3 - Because there are a few Astrocade enthusiasts curious about my final modified for hi-res Astrocade project, I thought it would be appropriate to post the following on the Astrocade discussion group site.

 

Adam Trionfo added his commentary to MCMs YouTube channel video entitled: MCMs Final Hi-Res Astrocade - Report 1.

 

Within his commentary, Adam inquired about the hi-res Astrocade's:

add-under Pattern Transfer Board 3 and

a possible modified Cartridge Connector Interface (CCI).

 

Adam also inquired about a major motherboard schematic error in the Bally PA-1 Service Manual.

 

THE PATTERN TRANSFER BOARD 3 (PTB3)

 

The PTB3 scheme will be taken from the coin-op Wizard Of Wor PTB scheme. MCM has already spent time on a feasibility study of the WOW PTB scheme and determined that this scheme is compatible with MCMs modified for hi-res Astrocade.

 

The WOW PTB functions like a digital logic graphics subroutine. Even though the board utilizes some slow CMOS chips, overall, the PTB graphics subroutine can execute faster than a similar subroutine in memory processed by a Z80 CPU operating with a 1.78 MHz system clock.

 

The PTB does not have to spend time fetching any Z80 instructions from memory. The PTB executes the graphics subroutine using digital logic gates.

 

The Z80 has to fetch an instruction from memory before it can execute it. The fetch time delay can take 4 or more system clock cycles, depending on how many bytes of Z80 machine code an instruction utilizes.

 

So, for the Astrocade's Z80 system clock of 1.78 MHz (560 nsec per cycle), there will be at least a 4 x 560 nsec delay just to fetch and instruction from memory.

 

This fetch delay will add up when the Z80 executes a subroutine because every instruction executed within the sub has to be fetched in order for the Z80 to process the entire subroutine.

 

The PTB3 project will be very time consuming. The scheme has to be breadboarded, tested and wire wrapped. MCM will have to determine specifically how the PTB scheme manipulates each graphic byte written to screen RAM for each of the 6 possible graphic write modes available.

 

There is just minimal programming documentation for the WOW PTB. MCM will likely have to create graphic machine language programs during the testing phase to completely understand how the PTB can manipulate graphic bytes. It is not clear at this time if the PTB can utilize the custom address and data chip's magic functions.

 

Why is MCM willing to spend an enormous amount of time to create the Pattern Transfer Board 3? Simply, because the possibility of having a fast PTB on a modified for hi-res Astrocade "is there" and could open the door to graphics manipulation never seen on an Astrocade. Combining that possibility with a multi-page (scene) option and up to 32KB available for a directly accessible program, addressed at 8000 - FFFFH, could provide the potential for some really awesome graphic games. The PTB challenge is there and MCM wants to attempt it.

 

Two other ideas relating to the PTB3 are on MCMs table.

 

1. Break down the WOW machine coding for its "attract" mode to see how the WOW PTB was utilized?

Program a close variation, as a hi-res demo, of that attract mode for execution on MCMs hi-res Astrocade?

MCM is not planning to break down WOW's "play mode" because MCM will convert the Astrocade's "The Incredible Wizard" to hi-res.

 

2. Create an upgraded variation of the PTB providing additional (extended) graphic manipulation?

 

THE MODIFIED CARTRIDGE CONNECTOR INTERFACE (CCI)

 

Another idea that is on MCMs table is the modified CCI. This interface scheme exists only on paper at this time. The modified interface is NOT related to the Astrobasic cartridge built-in audio interface.

 

The interface would require a minor rewire of the motherboard CC decoder. Some of the wiring would be connected to 2 DPDT mini-toggle switches mounted on the right side of the motherboard with the toggles protruding through the bottom of the Astrocade console.

 

With the 2 toggles in position 1, the CCI would be decoded normally at 2000 - 3FFFH. With the 2 toggles in position 2, the CCI would be decoded to function at 8000 - FFFFH.

 

There are enough contacts in the cartridge connector to run a 32KB EEPROM (or EPROM). A cartridge PC board would need a rewire to accommodate the 32KB chip. There would likely be a need for the bottom of the cartridge to have a gnd contact which would make contact with a gnd contact on the bottom of the floor of the cassette connector.

 

The intent of the modified CCI would be to optionally run 32KB cartridge programs at 8000 - FFFFH utilizing a 16KB hi-res BIOS at 0000 - 3FFFH. The hi-res BIOS, similar to the low-res BIOS, would be able to sense a cartridge at 8000H by checking for a cartridge sentinel at that address.

 

Larger than 32KB programs would be possible using more than 1 cartridge as long as the program allowed the user to insert another cartridge to continue the program. This possibility could be accomplished by loading/executing a loop program in screen RAM or including a standard loop program in the hi-res BIOS.

 

A MAJOR MOTHERBOARD SCHEMATIC ERROR IN THE BALLY PA-1 SERVICE MANUAL

 

This error was pointed to in the Bally schematic, documented and corrected within the Report 1 video indicated above at the video time interval 2:49 - 4:00. MCM has known about this error for years. The error is between the two U6 inverters gates, pin 4 to pin 1 and U20 pin 9.

 

The error correction is also documented on the Bally Alley. The correction appears in one of the handwritten scans within the BalcheckHR User Manual. The correction is in scan 9, The Bally/Astrocade Motherboard - Custom Address/Data.

 

Here's the link to the listing of handwritten scans for the BalcheckHR User Manual.

 

https://ballyalley.com/documentation/BallyCheck/BallyCheck.html#:~:text=BalcheckHR%20User%20Manual%20(Handwritten%20Scans)

 

 

End Of Report 3

March 2022

 

---------------------------------------

 

Thanks for the update, Michael.  I know that this documentation is time-consuming to make, so I appreciate that you dedicate your free time to allow us Astrocade fans to know about the progression of your hi-res project.

 

I hope that the construction of a hi-res pattern board goes smoothly for you.  Is the pattern board what allows the background stars to be generated in Wizard of Wor and Gorf?

 

Adam

Edited by ballyalley
Fixed a spelling errors.
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Michael posted some feedback for his video called "MCMs Final Hi-Res Astrocade - Report 2."  I've linked to this video in an earlier post in this thread, but for ease of use, here it is again:

 

https://www.youtube.com/watch?v=2AXRYxHDpaQ&lc=

 

Here is a direct link to this post on the Astrocade discussion group:

 

https://groups.io/g/ballyalley/message/19075

 

Here is what Michael said in his latest post:

 

---------------------------------------

 

From: Michael Matte

Sent: Sunday, March 27, 2022 11:04 AM

To: ballyalley@groups.io

Subject: Re: [ballyalley] MCM Design Hi-Res News

 

Report 4 - Adam Trionfo provided another commentary for MCMs YouTube video entitled: MCMs Final Hi-Res Astrocade - Report 2

 

A portion of my reply to Adam is related to my final hi-res Astrocade along with some info related to troubleshooting the Astrocade motherboard. I decided to post my reply also on the Astrocade discussion group site.

 

This time I'm including Adam's commentary followed by my reply.

 

Thanks Adam for spending the time to write and post your commentary to my video. It's encouraging to receive some positive feedback from a viewer of one of my videos.

 

ADAM'S COMMENTARY

 

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-ups 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.

 

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

 

---------------------------------------

 

About a week ago, my friend Carl was visiting me for a good part of a Saturday afternoon and evening.  Carl is a local Timex computer fan who I met through the TS2068 discussion forum on groups.io (https://groups.io/g/TS2068).  He was explaining how to burn an EPROM for a Timex/Sinclair 2068 computer cartridge.  He explained in detail the addressing lines of an EPROM and how they affect this particular Timex cartridge that I own.

 

Carl's insights have helped me to understand what Michael is talking about when he is describing his 32KB SRAM scheme for his hi-res Astrocade.  I love it when one computer hobby bleeds into another one.  We never know when this will happen.  When it does occur, which is more often than I might hope, then I understand and re-remember why I don't focus on just one classic computer or console.  In some ways, the more general my knowledge about 8-bit computers, then the more I find I can tune it specifically to the Bally Arcade/Astrocade.

 

Adam

 

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Michael posted some additional information about the pattern transfer board and how it relates to "Wizard of Wor," a hi-res game.  Here is a direct link to this post on the Astrocade discussion group:

 

https://groups.io/g/ballyalley/message/19119

 

Here is what Michael said in his latest post:

 

---------------------------------------

 

From: Michael Matte

Sent: Tuesday, March 29, 2022 1:00 AM

To: ballyalley@groups.io

Subject: Re: [ballyalley] MCM Design Hi-Res News

 

Adam commented on my posting of MCM Design Hi-Res News - Report 3, group posting #19035, Mar 25

 

Below is Adam's comments with a question about the coin-op WOW and Gorf pattern transfer board.

My reply follows Adam's comments.

 

Adam Trionfo

Mar 28   #19101

Thanks for the update, Michael.  I know that this documentation is time-consuming to make, so I appreciate that you dedicate your free time to allow us Astrocade fans to know about the progression of your hi-res project.

 

 I hope that the construction of a hi-res pattern board goes smoothly for you.  Is the pattern board what allows the background stars to be generated in Wizard of Wor and Gorf?

 

I posted this third update to the hi-res thread on AtariAge:

 

https://atariage.com/forums/topic/254592-hi-res-bally-arcadeastrocade-correspondence/?do=findComment&comment=5030154

 

This is more great information from our Astrocade hi-res guru.

 

Adam

 

 

MCMs REPLY

 

Adam, I think you were asking if the coin-op pattern transfer board (PTB) created the star twinkling effect. That's a really good question.

 

The PTB could have been used to initially write each star. A x,y coordinate randomizing routine was also likely used initially to write each star.

 

However, I have reason to believe the twinkling effect was generated by additional chips on the coin-op logic board not the PTB.

 

When you look at the logic board schematic, on the left there is a scheme with its output connected to the video line. On the input side of the scheme there are 4 input lines labeled as

 

STARS

SPKL 1

SPKL 2

SPKL 3

 

SPKL = Sparkle

 

These 4 input lines could likely be set (enabled?) by a single output port. According to the WOW disassembly on the Bally Alley, digital design trickery may have been utilized so these lines could be enabled by an input (not an output) to port 14H.

 

I just browsed the WOW logic board schematic. I did not dig deep into this scheme, but it looks like the WOWs PTB does NOT twinkle the stars or sparkle specific graphic patterns.

 

Some time ago, I asked myself the same question about the stars twinkling. This is why I'm thinking of breaking down the machine coding for WOWs "attract" mode because I could likely learn a lot about the PTBs application.

 

End of reply

MCM Design Hi-Res News - Report 3

March 2022

 

---------------------------------------

 

Michael's work into examining the arcade game "Wizard of Wor" will be interesting to follow.

 

Adam

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  • 5 months later...

I had been spending quite a bit of time with another Z80 computer, the Timex 2068, when I got an email from Michael Matte.  He was having some trouble with a version of Windows Movie Maker, which he seems to have corrected.  He gave me an update about his Astrocade projects in this last of our emails that we exchanged together, which I'm including here, and which I also posted to the Astrocade dicussion group, here:

 

https://groups.io/g/ballyalley/message/19413

 

One day someone will post a message here that they have also updated their Astrocaded to have access to hi-res mode.  Will that person be you?

 

Adam

 

---------------------------------------

 

From: Michael Matte

Sent: Sunday, August 14, 2022

To: Adam T.

Subject: [Astrocade Updates from Mid-August 2022]

 

Actually, I'm planning to record a video later. I'm not ready yet to record a video until specific hardware projects are completed. I don't recall why I decided to access my WLMM a few days ago. That's when I couldn't find that program.

 

I'm still experimenting with my YouTube channel videos. I'm going to try my 19"LED TV and see what happens. I'm also going to look into the possibility of recording short videos in HD.

 

My newly revised BalcheckHR WW prototype board is finally finished.

 

My quick connect composite video driver and audio driver board is still in the development stage.

 

I spent more time experimenting on my breadboard with the low/hi-res screen SRAM interfacing scheme and eventually came up with a really cool idea, which required only a minor rewire. I may post or record a video to demonstrate how this latest change has created a major compatibility improvement on this scheme.

 

Because of the several interfacing changes that have been made on my final hi-res SRAM Astrocade project, drawings DWG 2, 3, 4 and 5 posted on the Bally Alley are now obsolete. I plan to revise/update all 6 drawings, assigning a revision number to each.

 

As a result of the recent SRAM interfacing change, the "low-res only" breadboard that can plug into my modified for hi-res Astrocade motherboard has been simplified. Two chips have been eliminated. This simplified scheme will eventually end up on a WW board.

 

This latest interfacing change has also opened the door for a low-res modification option on an Astrocade motherboard which has a DRAM or DRAM interfacing failure.

 

I have come up with a very clean way as an option to replace the DM81LS95 (U23) chip and 8 DRAM chips with just 2 chips: the 74LS373 (or equal) and 1 SRAM chip. I'm pretty sure, at this time, a 0.6" wide body SRAM chip could even be used.

 

You should later expect to see a posting and likely a video on this new option, after I build and test the quick connect SRAM board that would plug into a U23 socket and U24 DRAM socket using short looped DIP ribbon cables. No further motherboard modifications would be required. When I will build this new scheme I don't know.

 

Since Allen Schweitzer is occasionally replacing 8 RAMS with 5v only RAMs another, perhaps simpler, option might be to plug in a pro-grade designed pc board with this new SRAM scheme.

 

Bye.

MCM

 

---------------------------------------

 

As always, even in the background, Michael is thinking about his Astrocade projects.

 

Adam

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  • 2 months later...

Here is another Hi-Res update from Michael.

 

Adam


--------------------

 

From: Michael Matte
Sent: October 14, 2022
To: BallyAlley Discussion Group
Subject: MCM Design Hi-Res News - Report 5 (Updates + Hi-Res Graphics Source Code)

 

The full thread can be found here:

 

https://groups.io/g/ballyalley/topic/94340628

 

The 8.5 x 8.5" low/hi-res screen SRAM Board 1 has been tested to run perfect with SRAM of various access times: 75, 85, 100, 120 and 150ns. The board runs perfect in low and hi-res.
 
MCM plans to record a video demonstrating BD1, once the newly revised low-res only screen SRAM scheme plus the quick-connect composite video/audio drivers scheme are wire wrapped on Vector boards. How long will it take to WW these 2 boards? Not sure, 5 weeks, maybe longer.
 
MCM is planning to WW a backup BD1 as a test for compatibility and as a quick check diagnostic tool.
 
A fourth Astrocade motherboard MIGHT be modified for hi-res as a final test for compatibility.
 
The second modified for hi-res Astrocade motherboard has a failure on it and needs to be diagnosed.
 
The hi-res schematic DWGs 2, 3 and 4 archived on the Bally Alley should now be considered OBSOLETE (having limited compatibility). A bunch of improvements have been made on BD1. These DWGs should really be deleted from the website, to eventually be replaced with newly revised DWGs 1 thru 6, which will include a revision number.
 
FYI, the 8KB BalcheckHR program package includes 3 hi-res graphic demos listed below:
 
Move Critter, Wagon and Fish (original hi-res demo)
Textured 10 Color Test Pattern Variation
The Pixel Stringer
 
Note that a low/hi-res software select scheme is required to run these 3 programs. They are not accessible using a manual low/hi-res mini-toggle switch.
 
The BalcheckHR bin file and source code are archived on the Bally Alley. The source code includes extensive program comments.
 
Two other hi-res programs are also included with BalcheckHR:
 
Hi-Res SetScreen2
Hi-Res Screen RAM Test Program (similar to the low-res Balcheck screen RAM test).
Both programs require the use of a dual 7-segment display to report specific diagnostic info.
 
Finally, the entire BalcheckHR package will run in hi-res by changing only 13 bytes within the 8KB coding. This change is documented in the BalcheckHR User Manual. Low-res graphics will be displayed only within the top 1/4 (4000-4FFFH) area of the hi-res display. Because of the way the hi-res screen RAM is mapped, the low-res graphics will be split in two, on the left and the right sides.
 
 
End Of Report 5
MCM Design
Oct 2022

 

--------------------

 

Ken Lill replied, "Consider the fact that the first Bally's were run on 450uS DRAMS, almost any SRAM now will blow that timing out of the water."

 

--------------------

 

On October 16, Michael Matte replied:

 

Ken's posting #19534 indicated relating to my testing of the low/hi-res screen RAM BD1 using 70, 85, 100, 120 and 150ns SRAM, "Consider the fact that the first Bally's were run on 450uS DRAMS, almost any SRAM now will blow that timing out of the water".
 
You were careful to suggest that ALMOST any SRAM speed would work on my BD1 scheme.
 
Not to long ago, I breadboarded a "low-res only" SRAM scheme using the same DRAM interfacing scheme utilized on the Astrocade motherboard.
 
This breadboard would connect to my "modified for hi-res" Astrocade motherboard, which has a 28 pin DIL connector mounted on it. The connector has 28 tapped motherboard signal lines wired to it.
 
The breadboard generated the active low CS/RAS, CAS, WE lines and had access to the DATEN line, nearly identical to the same motherboard DRAM control lines. No 2K pull-up resistors were used. Also, there were no 1K pull-ups on the load side of U20 (74LS174) for the RAM A0-A5 lines.
 
All I had to add to complete the SRAM interfacing scheme was a 74LS373 to latch in the SRAM row address.
 
I tried SRAM with a 120ns and 70ns access time. This low-res SRAM scheme worked perfect.
 
However, when I used a narrow package Cypress CY7C185 8KB SRAM with a 15ns access time, the SRAM scheme would not work right.
 
I ran my Z80 Check and Fill Screen Write programs. These 2 programs only write graphics to screen RAM. The Z80 does not read screen RAM or utilize a stack area in it. It was obvious that the Z80 had some kind of an issue writing to this faster SRAM chip.
 
I did not spend any time to determine if there was also a read issue with this faster chip. I may spend some time later trying to determine the cause of this write issue. Maybe my logic analyzer might reveal something.
 
Any idea Ken why this 15ns SRAM chip is not operating perfect? I triple checked the wiring to the chip.
 
The breadboarded low-res SRAM interfacing scheme described above is implying that the Astrocade motherboard U23 (DM81LS95) and 8 DRAM chips can be replaced with only a 74LS373 and one SRAM chip. All the RAM interfacing lines can be taken from the U23 and U24 (DRAM) solder pads, including the +5v and gnd lines. A DIL pc socket could be soldered onto each of these 2 solder patterns. This would provide a quick connect for a small pc board with a 74LS373 and one SRAM plus 2 DIL ribbon cable plugs on it. This pc board would sit on top of the motherboard were the 8 DRAM chips use to be. You might have to remove the 9 motherboard pull-up resistors.
 
I may later test this implication on one of my "modified for hi-res" Astrocade motherboards.
 
When I first breadboarded my low/hi-res SRAM scheme, I was using only 120ns SRAM. The scheme was working perfect in low and hi-res.
 
Then later, I found out my low/hi-res SRAM scheme wouldn't work right using faster SRAM. If I recall correctly, the scheme had an issue with a 100ns SRAM.
 
So, I was forced to return to my breadboard and had to revise the scheme, so it would run my 70, 85 and 100ns SRAM perfect in low and hi-res.

Mister HR

 

--------------------

 

Michael's progress continues a bit every month.

 

Adam

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